GENERAL METHODS
Report about study participants and details about visual stimuli, rivalry task, and perceptual selection measure implemented in the study. "Catch trials" were used to control for response bias, and eye-dominance was measured so that participants with >85% dominance of one eye could be excluded.
In three additional experiments, we showed that only pat-terns of visual stimulation in the recent time period before theonset of rivalry contributed to the prediction effect and thatprediction of the upcoming stimulus and adaptation to preced-ing stimuli had separate influences on perceptual selection.
How do adaptation and the effect of stimulation prior to rivalry on prediction relate to the experimental paradigm as a whole? Are they intended to control for confounding factors?
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The study hypothesizes that predictive neural activity influences perceptual selection of visual stimuli. If true, selection of stimuli in multistable perception should bias according to what the brain expects from prior experiences. The results of the study provide support for this idea.
LGN
The lateral geniculate nucleus, which receives visual inputs and organizes them for conscious perception in the cortex.
V1
The primary visual cortex, which is the first cortical area to receive visual information (prior to processing).
INTRODUCTION
Prior knowledge about or exposure to visual stimuli influences how they will be perceived in the future. The brain perpetually makes predictions about incoming sensory information, but the effect of predictive neural activity on perception of ambiguous stimuli is not known. Research suggests that cuing or priming a particular stimulus (predictive context) prior to binocular rivalry or ambiguous motion tasks will bias perceptual selection of that stimulus during those tasks. binocular rivalry is ideal for studying the effect of predictive context on perceptual selection, because it forces the brain to make a decision between competing inputs. This study used a novel binocular rivalry paradigm to test how expectations shaped by prior stimuli influence which percept is selected. It was found that the brain areas which contribute to perceptual selection during binocular rivalry generate predictive signals, indicating that our brains use prior sensory information to generate perceptual experience.
Subjects’ perceptual reportswere influenced by the pattern of the preceding sequence, withan increased probability of interpreting ambiguous motion in amanner that was consistent with the expectation generated by thesequence.
Does this study demonstrate the same/similar conclusion as the two previous ones (apparent motion rather than binocular rivalry)?
unam-biguous low-contrast stimuli (
Stimuli which are straightforward in meaning or structure (not open to multiple interpretations) but have minimal differences between light and dark areas (difficult to see clearly).
secondary cues
Cues which are not the attentional focus but provide additional context or meaning to primary cues, which are the attentional focus.
predictive context.
Refers to when the brain uses previously perceived information to help interpret information perceived in the future.
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Describes the neural dynamics associated with auditory stream segregation and the verbal transformation effect (examples of auditory multistable perception).
Importantly, multistable perception occurs across sensory modalities. Auditory and visual multistable perception may involve similar neural mechanisms.
Figure I.
Visual representation of how auditory stream segregation is triggered and perceived.
Box 1. Auditory multistable perception
Figure 1. Examples of multistable visual phenomena.
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Main idea is that fMRI studies have consistently shown a relationship between neural activity in V1 and LGN (early visual processing areas) and the resolution of binocular rivalry, even though electrophysiological studies have not demonstrated this relationship. The explanation for this is hard to understand but essentially it seems like the type of neural activity most associated with perceptual awareness (local field potentials) is easier to track using fMRI than electrophysiological methodology, hence fMRI is more useful for studying the neural underpinnings of binocular rivalry than electrophysiological studies.
(c)
Bistable perception example: binocular rivalry (highly relevant).
(b)
Bistable apparent motion perception example: the spinning wheel illusion.
(a)
Bistable perception example: the Necker cube (most cited).
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When sensory information about a perceived stimulus is ambiguous, the visual system forms multiple distinct interpretations of said stimulus. Multistable perception occurs when perception of the stimulus alternates between interpretations over time.
Multistable perception may arise from interactions between lower-order and higher order brain processes. Lower order brain processes are involved in basic mental functions such as attention and perception, whereas higher order brain processes are involved in complex mental functions such as reasoning and abstract thinking.
The review discusses how brain processes underlying different levels of visual processing (low-level sensory, intermediate extrastriate, and high level frontoparietal) interact with one another to produce visual multistable phenomena such as binocular rivalry.
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Content specific NCC are neuronal populations which are active when specific "contents of experience" are perceived or thought about, and are inactive otherwise. For example, if the NCC for experiencing the contents of a face are stimulated
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NCC can refer to content-specific NCC or full NCC.
Vegetative state
Disorder of consciousness in which patients retain autonomic reflexes and the ability to spontaneously open their eyes despite being completely unresponsive in every other way.
Hot zone
An area of the posterior cerebral cortex spanning the temporal, parietal, and occipital lobes. There is a strong possibility that it is the location of the full and content specific NCC. Content specific NCC are populations of neurons associated with specific perceptual experiences (e.g., facial recognition).
No‑report paradigm
An experimental model in which groups that provide subjective reports of what they perceive (a presented stimulus) are compared with groups that do not provide such reports. Instead, we attempt to determine what the latter group is perceiving via physiological measures (neuroimaging technology). This method allows the NCC to be distinguished from activity which relates to them.
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In behavioral paradigms, consciousness is evaluated using verbal reports or physical responses indicating the perception of a presented stimulus. The accuracy of these reports/responses is unreliable when said stimuli are dubiously perceptible, because it is hard to tell whether the subject actually perceived the stimulus or simply guessed its position correctly. Forced-choice procedures can determine the subject's objective awareness of the stimulus by minimizing their subjective bias.
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Some paradigms evaluate consciousness via subjects rating the extent to which they perceived a presented stimulus, as well as their confidence regarding the accuracy of that perceptual judgment. Such methods minimize inconsistencies between subjective and objective consciousness measures.
Neural correlates ofconsciousness
The minimum neural processes which are together required (necessity and sufficiency) for an individual to experience any one particular conscious precept (seeing, hearing, thinking, feeling, etc.)
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Clinically, consciousness is measured via a subject's behavioral responses, but their absence does not necessarily imply a lack thereof (as with minimally conscious subjects). A subject's level of consciousness (auditory, visual, verbal, motor) is typically rated using standardized scales.
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Consciousness relies on proper functioning of midline brain structures, and specific experiences are related to particular neuronal activity in the cerebral cortex. Research on the neural correlates of consciousness (NCC) relates behavioral correlates of consciousness to underlying neural mechanisms. Evidence from no-report paradigms suggests that the NCC may be restricted to a posterior cortical hot zone rather than generalized to a broad frontoparietal network (as was previously thought).
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Consciousness is essentially phenomenological experience (seeing, hearing, thinking, feeling). It persists during dreams, and ceases during dreamless sleep. The neurophysiological origin of consciousness is an open question in philosophy, psychology, and neuroscience.
Neural correlates of consciousness
Behavioural correlates of consciousness
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Some experiments which involve conscious perception of external stimuli with reports/tasks have shown activation of prefrontal areas, but this activation may have been related to the reports/tasks rather than the conscious experiences (not indicative of content-specific NCC). Other experiments which involve conscious perception of external stimuli without reports/tasks showed more posterior activation than anterior activation (indicative of content-specific NCC).
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Within-state paradigms comparing conscious individuals to unconscious or minimally conscious individuals have revealed posterior area activity to show the most difference between consciousness and unconsciousness or minimal consciousness (there is a "posterior hot zone" which may be indicative of the NCC).
However, neuroimaging experiments can sample brain activ-ity systematically and noninvasively in healthy volunteers (Pol-drack and Farah, 2015) and, with appropriate methodologies,they can also provide valuable information about the functionalspecificity of brain regions (Moran and Zaki, 2013; Poldrack andFarah, 2015).
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Compared with case studies (lesions) and electrical stimulation studies, neuroimaging studies are less accurate in determining the exact brain regions that contribute to consciousness. Neuroimaging often covers multiple brain areas, some of which may not be directly involved in modulating content-specific NCC.
C
bottom-horizontal fMRI images of someone wo experienced anoxic lesions to their posterior corpus callosum, resulting in permanent coma following head trauma.
F
Sagittal fMRI image of an individual who displayed content-specific changes in experience (feeling of intention to move) following electrical stimulation of the temporoparietal cortex.
D
Mid-sagittal fMRI image of an individual who displayed content-specific changes in experience (intrusive thoughts) following electrical stimulation of the ACC.
E
Bottom-horizontal fMRI image of an individual who displayed content-specific changes in experience (inability to perceive faces) following electrical stimulation of the fusiform gyrus.
Together, stimulation studies support the idea that some pos-terior cortical regions may contribute directly to specific contentsof experience, but the evidence for prefrontal regions is scarceand indirect.
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Many studies have demonstrated that electrical stimulation of the posterior cortex induces discrete changes in the content-specific NCC more reliably than electrical stimulation of the anterior cortex. Hence, most evidence suggests that posterior regions of the brain contribute more to the content-specific NCC than do anterior regions of the brain.
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For the most part, electrical and TMS stimulation of the frontal cortex does not elicit content-specific changes in experience. Stimulation of the ACC and MCC (posterior areas), however, does elicit some content-specific changes in experience, suggesting that posterior area stimulation is more likely to excite content-specific NCC than frontal area stimulation.
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Several studies have shown that electrical stimulation and EEG activation of posterior cortical areas is effective at restoring consciousness in subjects where it is impaired, demonstrating that the excitability of the full NCC can be modulated through arousal systems.
Electrical stimulation during neurosurgery is an important source ofevidence for a direct contribution of different brain areas to con-sciousness (Penfield, 1959; Desmurget et al., 2013), as indicatedby its superior value in predicting postoperative deficits com-pared with fMRI or diffusion tensor imaging (Borchers et al.,2011).
diffusion tensor imaging
A technique that detects how water travels along the white matter tracts in the brain.
Figure 2.
anatomical images depicting clinical evidence for the full (A, B, C) and content-specific (D, E, F) NCC.
Although frontal injuries can slightlyincrease the threshold for perceiving some brief (16 ms) andmasked visual stimuli, patients still experience them (Del Cul etal., 2009), suggesting that these frontal regions may modulate theNCC (i.e., act as background conditions) rather than contribut-ing directly to consciousness (Kozuch, 2014).
By contrast, there is little evidence for loss of specific con-scious contents after frontal damage (Penfield and Jasper, 1954).
prosody
Patterns of rhythm and sound used in poetry.
With regards to content-specific NCC, there is abundant neu-rological evidence that lesions in the posterior cortex can cause aloss of specific contents of experience (Farah, 2004).
B
mid-sagittal fMRI image of someone who experienced anoxic lesions to their posterior corpus callosum, resulting in permanent VS following head trauma.
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traumatic lesions to the posterior corpus callosum appear to permanently cause states of VS (coma, or impeded consciousness), whereas traumatic lesions to the frontal lobe do not seem to do this.
VS
Behavioral state similar to coma.
A,
Bilateral view of the left and right frontal lobes of someone who experienced extensive prefrontal lobe damage without a noticeable change in consciousness, with certain anatomical regions labeled (top). Lateral view of the left and right hemispheres of that same individual, with certain anatomical regions labeled (bottom).
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There are many examples of people who have experienced bilateral lesions to the frontal lobe and still retained most, if not all aspects of consciousness. These instances lend credence to the idea that the anterior cortex may not account for the full NCC. Even when such damage causes deficits in cognition, perception, or executive function, consciousness does not appear to be significantly altered and effected individuals still seem capable of living normal lives.
Figure 1.
The NCC and related processes represented in a diagram of the brain. Content-specific NCC are represented in red, full NCC are represented in orange (as a union of all content-specific NCC), neuronal activating systems and global enabling factors modulating full NCC activity are represented in green, processing loops modulating some content-specific NCC are represented in beige, sensory pathways modulating some content-specific NCC are represented in pink, and outputs from NCC are represented in blue.
For content-specific NCC, experimentscan be carefully designed to systematically investigate possibledissociations between the experience of particular conscious con-tents and the engagement of various cognitive processes, such asattention, decision-making, and reporting (Aru et al., 2012; Kochand Tsuchiya, 2012; Tsuchiya et al., 2015; Tsuchiya and Koch,2016).
Several complementary methods can be used to distill the trueNCC. For the full NCC, within-state paradigms can be used toavoid confounds due to changes in behavioral state and taskperformance as well as to dissociate unconsciousness from unre-sponsiveness
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Recent research has placed emphasis on distinguishing "background conditions" that indirectly generate consciousness from neural processes that directly generate consciousness (or distinguishing consciousness itself from its precursors and consequences). Some neural processes, such as processing loops involved in executive functions, activity along sensory pathways, and activity along motor pathways may tangentially affect the full NCC via modulation of the content specific NCC.
The full NCC can be definedas the union of all content-specific NCC (Koch et al., 2016a).
scious percept (Crick and Koch, 1990). Content-specific NCCare the neural mechanisms specifying particular phenomenalcontents within consciousness, such as colors, faces, places, orthoughts.
The neural correlates of consciousness (NCC) are defined as theminimal neural mechanisms jointly sufficient for any one con-
mesocircuit
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prerolandic
Analogous to "precentral."
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It is clinically and scientifically imperative that we develop a more comprehensive understanding of the neural correlates of consciousness. Many scholars believe that the frontal areas of the cerebral cortex are most crucial for supporting consciousness. This article proposes that both the "front" and "back" regions of the cerebral cortex play an important role in this function. The presence or absence of consciousness when other brain areas are damaged or nonfunctional is also discussed.
The role of the frontal cortex in consciousness remains a matter of debate. In this Perspective, we will critically review the clinical andneuroimaging evidence for the involvement of the front versus the back of the cortex in specifying conscious contents and discusspromising research avenues.
e
Visual representations of auditory-driven visual percepts observed by participants as per their descriptions/drawings. Depictions are consistent with Kluver form constants.
d
Proportion of trials in which participants observed visual percepts for louder (70 dB) and softer (60 dB) beep trials for experiment 2. Auditory-driven visual percepts were significantly more likely to occur following a loud sound than following a soft sound (**).
c
Proportion of trials in which participants observed visual percepts as spatially aligned, spatially misaligned, or spatially undefined with the location of the sound for experiment 2. Auditory percepts were significantly more likely to occur at the spatial location of the sound (***).
Consistent with these reports,we found no differences in the frequency of these percepts between the first and second half of the experiment (Z = 0.085, p = .932,r = 0.013).
We additionally examined whether the frequency of these experiences varied throughout the experiment to clarify additionalelements of this phenomenon.
Participants demonstrated a significantly higher frequency of visual percepts onbeep trials (Z = 1.992, p = .046, r = 0.307; Fig. 1A), consistent with our suggestion that startling tones presented in the context ofmild visual deprivation can lead to auditory-visual percepts.
b
Proportion of trials in which participants observed visual percepts for trials that involved a beep and trials that did not involve a beep for experiment 2. Participants demonstrated significantly more visual percepts in response to beep trials than in response to non-beep trials (***).
a
Proportion of trials in which participants observed visual percepts for trials that involved a beep and trials that did not involve a beep for experiment 1. Participants demonstrated significantly more visual percepts in response to beep trials than in response to non-beep trials (*).
Fig. 1.
Experiments 1 and 2 results.
We first examined whether it is possible to evoke auditory-visual synesthesia in non-synesthetes undergoing short-term sensorydeprivation and parameterized the features that maximize the strength of these experiences (Klüver, 1966).
phosphenes
A ring or spot of light produced by pressure on the eyeball or direct stimulation of the visual system other than by light.
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In the cross-activation model, it takes years for the brain to change its structure to facilitate synesthesia. In the disinhibited-feedback model, it takes minutes for the brain to change its structure to facilitate synesthesia. The current study attempts to support the disinhibited-feedback model by demonstrating that non-synesthetes can experience synesthesia under mild sensory deprivation.
Conversely, the disinhibited-feedback model proposes that everyone possesses the potential to experience synesthesia, mani-festing only when the balance of activity across the senses has been altered (Grossenbacher & Lovelace, 2001). According to this view,the anatomical structure of the brains of synesthetes and non-synesthetes is generally similar, but there are differences in howeffectively one sense can evoke activity in a second modality, potentially due to weaker inhibition of feedback projections thatconnect the sensory systems (Grossenbacher & Lovelace, 2001). For example, instead of abnormal connections enabling sounds toevoke conscious visual experiences in synesthetes (as in the cross-activation model), this model argues that these connections arepresent in all individuals and that synesthetes have less inhibition restricting how strongly sounds modulate visual activity.
If all individuals possess the ability for one sensory system to modulate activity in another, why do only a minority of individualsexperience synesthesia? The cross-activation model reconciles this discrepancy by arguing that synesthesia arises from anatomicalpathways that are either weak or absent in non-synesthetes, providing a direct link through which one sensory modality can stimulateanother modality (Hubbard, Arman, Ramachandran, & Boynton, 2005; Hubbard, Brang, & Ramachandran, 2011; Ramachandran andHubbard, 2001a, 2001b, 2003).
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Sounds can evoke conscious visual experiences in individuals with sound-color synesthesia (genetic predisposition). Synesthesia is when stimulation of one sensory modality elicits conscious experiences in a second sensory modality. There is no evidence of a mechanistic relationship between synesthesia and non-synesthetic multi-sensory interactions.
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The auditory and visual systems of the brain are interconnected, such that activity in the visual system is capable of altering activity in the auditory system, and vice versa. While sounds can modulate activity in visual areas in the absence of visual stimuli, it is generally the case that sounds cannot evoke conscious visual sensations in the absence of visual stimuli.
Competing models differ in the time required for synesthetic experiences to emerge. Thecross-activation model suggests synesthesia arises over months or years from the development ofabnormal neural connections. Here we demonstrate that after ∼5 min of visual deprivation,sounds can evoke synesthesia-like percepts (vivid colors and Klüver form-constants) in ∼50% ofnon-synesthetes. These results challenge aspects of the cross-activation model and suggest thatsynesthesia exists as a latent feature in all individuals, manifesting when the balance of activityacross the senses has been altered.
Klüver form-constants
Geometric patterns observed during altered states of consciousness which resemble tunnels, spirals, honeycombs, gratings, and cobwebs.
qualia
Instances of subjective, conscious experience.
Characteristic path length (CPL)
Broadly refers to how efficiently information is transferred within a neural network of the brain. Important for measuring and analyzing brain connectivity patterns.
transitivity
Broadly refers to how interconnected or organized a neural network of the brain is. Important for understanding the structure and function of neural networks.
PLV
Phase-locking value. A statistical measure of the extent to which oscillatory activity in different brain networks is synchronized, for the purpose of determining how interconnected those brain networks are.
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Power and connectivity in the delta frequency band increase during unconsciousness, possibly because thalamocortical neurons rapidly alternate between increased and decreased activity at that time. Functional connectivity of the brain may become less complex during unconsciousness due to this rapid alternation.
Figure 2.
Characteristic path length (CPL) and transitivity of consciousness and nonconsciousness based on phase-locking values.
Table 1.
TMS-induced and TMS-evoked spectral power in frontal and parietal regions did not significantly differ between consciousness and nonconsciousness in any bands.
Figure 1.
Phase-locking value was significantly higher for states of nonconsciousness than for states of consciousness in the delta and theta bands. It was also significantly higher for states of consciousness than for states of nonconsciousness in the alpha and beta bands.
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The current study evaluated the effects of TMS perturbation on functional connectivity during consciousness and unconsciousness. It was predicted that synchronization of oscillatory activity would be higher in consciousness than in unconsciousness (because of coordinated bistability being higher), and that local aspects of functional segregation would happen strongly during unconsciousness.
delta (1–4 Hz) frequency band
A range of frequencies which appear on EEG recordings and which denote the occurrence of NREM sleep (deep, dreamless sleep).
negative EEG peak amplitude
EEG recording of the brain exhibiting a downward deflection/decrease in electrical activity when compared to baseline.
coordinated bistability
The ability of neuronal networks to coordinate activity between two stable states, e.g., between high activity (high rate of depolarization) and low activity (high rate of hyperpolarization).
Using this approach,a recent study found that spectral power in the delta band in posterior cortex was higher during reported uncon-sciousness than during reported consciousness 23 . Furthermore, using a within-state design in NREM sleep, ithas been found that TMS triggers a larger negative EEG peak amplitude during reported unconsciousness thanduring reported consciousness, indicating that differences in consciousness within the same physiological stateare related to local alterations in the cortical bistability of posterior brain regions 21.
Previous studies have mostly compared wakefulness with sleep or anesthesia to evaluate features associatedwith the level of consciousness in healthy individuals 14,18,19 . However, such studies are confounded by otherchanges that occur across global state shifts, such as changes in the cardiovascular, respiratory, and neuromus-cular systems 20 . To address this issue, recent studies have measured the presence or absence of consciousnesswithin the same physiologically categorized state using a within-state paradigm21–23.
spectral power
The intensity/magnitude of electrical activity at specific frequencies (in this case, the delta band) within a neural signal measured using EEG.
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TMS can effectively probe functional connectivity differences between conscious and unconscious brain states. EEG studies have demonstrated that functional connectivity breaks down in unconscious states by showing that brain responses to TMS are less complex during said states.
Together these resultssuggest that alterations in spectral and spatial characteristics of network properties in posterior brainareas, in particular decreased local (segregated) connectivity at low frequencies, is a potential indicatorof consciousness during sleep.
The neuronal connectivity patterns that differentiate consciousness from unconsciousness remainunclear. Previous studies have demonstrated that effective connectivity, as assessed by transcranialmagnetic stimulation combined with electroencephalography (TMS–EEG), breaks down duringthe loss of consciousness.
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The stress and responsibilities of reintegrating into society are especially challenging for dually diagnosed persons, as many of them lack the interpersonal and life skills to do so. It is therefore important for mental healthcare professionals to assist them in developing these skills.
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Dually-diagnosed persons may have an especially difficult time avoiding drug use due to lack of satisfying activities and relationships in their lives, further emphasizing the importance of providing them with opportunities to engaging in enjoyable activities relationships in the context of treatment.
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Many participants reported relapsing due to negative emotional states or to self-medicate for psychiatric conditions.
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Relapse was common among participants, and boredom was one of the most frequently cited reasons for participant relapse. It is therefore important for dually-diagnosed persons to engage in structured social and recreational activities as part of their SUD treatment. The study was unable to determine how much of a role physical cravings play in the desire of dually-diagnosed individuals to use substances.
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Implications of these findings are that preventative measures regarding substance use should be implemented in the ASD population, and that comprehensive psychiatric examinations should be done in individuals with ADHD, ID, and ASD to determine what SUD treatment methods are most effective for each. Another implication is that attempts to treat SUD in ASD should consider vulnerabilities of first degree family members.
We aimed to investigate the risk of substance use-relatedproblems in ASD. We also tested if any association betweenASD and substance use-related problems could be related tocomorbidity with ADHD or intellectual disability (ID). Toelucidate if shared familial factors underlie both ASD andsubstance use-related problems, we examined the pattern ofsubstance use-related problems also among unaffected rela-tives of individuals with ASD.
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The study was limited in that it was not able to determine whether shared familial background between ASD and substance use-related problems was due to genetic or environmental factors, and in that it did not differentiate between different forms of autism (although the DSM-5 does not distinguish between types of autism).
In other words, register-based stud-ies are likely to underestimate the absolute prevalence ofsubstance use disorder since users not in contact with thetreatment system are not taken into account (EMCDDA2004).
Second, we could stratify our analysis on comorbidADHD and ID only when those disorders were diagnosed,but it impossible to rule out that patients with seemingly“pure” ASD have undiagnosed ID, ADHD, or subthresh-old ADHD-symptoms involving substance use-relatedproblems
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The study may have been biased in that it targeted populations which were more likely to have substance-use related problems in addition to ASD. However, it also found the same results in populations that weren't as likely to have substance-use related problems in addition to ASD.
Strengths include the large scale population-based design,prospectively collected data from nationwide registries,stratification by comorbid disorders, statistical control forsocio-demographic confounders, and analysis of familialaggregation data from relatives. Nevertheless, some limita-tions deserve comments.
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Non-autistic relatives of autistic probands were at an increased risk for substance use-related problems. This correlation provides evidence for shared familiar liability regardless of ASD diagnosis. There are several possible explanations: that ASD and substance use-related problems share genetic risk variants, that parental SUD increases rates of mutations involved in ASD due to teratogenic effects of substances, or that associations between ASD and substance use-related problems are caused by shared environmental factors.
We can only speculate that the same familial factors maybe causal in substance use-related problems among ASDprobands may lead also to higher risks of substance-relateddeath among their non-ASD relatives.
As a result, it turned out that patients with ASD only andASD with ADHD are actually on comparable risks of sub-stance use-related problems (OR 1.6 vs. 1.9) and previouslydescribed extremely high risk in patents with ASD andADHD seems to be due diagnostic biases.
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In the study, the three most commonly cited strategies to stop substance use were 12-step meetings, formal treatment, and quitting "cold turkey." The effectiveness of formal treatment has been well-documented for both dual-diagnosed and single-diagnosed persons. While 12-step programs have been found to be effective for single-diagnosed persons, the effectiveness of 12-step for dually-diagnosed persons has been under-researched. Quitting drugs "cold turkey" has been documented in both dual-diagnosed and single-diagnosed drug users, but is much less common.
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In this study, one of the most frequent motivations to cease substance use was the negative consequences of substance use. Dually diagnosed substance users often consider only short term consequences of substance use, and so do not take them into consideration when using substances. Over time, however, the long term consequences of substance use become bad enough that even dually diagnosed people curb or decrease their substance use.
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Participants usually started using substances to "fit in" with peers during adolescence. It may be the case that mentally ill adolescents have an especially strong need to fit, since being mentally ill may cause them to feel alienated from their peers. It has been suggested that they seek out drugs because of this, and often find belonging in drug-related social networks where people are more accepting of differences.
Table 3
The first table depicts mean percentages for participants' descriptions of "what [was] going on inside of [them]" that triggered them to return to substance use after a drug-free period of one month or longer. The most common responses were "lonely, bored" (31%) and "craved, wanted to use" (31%).
The second table depicts mean percentages for participants' descriptions of "what happened in the outside world (social situation, event)" that triggered them to return to substance use after a drug free period of one month or longer. The most common responses were "temptations" (28%) and "stress/responsibilities" (28%).
Table 2
The first table depicts mean percentages for participants' stated reasons as to why they stopped using drugs. The most common reason participants gave for no longer using was "wanted a better life/tired of drugs" (54%).
The second table depicts mean percentages for participants' stated methods for stopping drug use. The most commonly cited methods by participants were "12-step/self-help groups" (45%), "treatment" (34%), and "cold turkey/willpower" (30%).
Table 1
The first table depicts mean percentages for each substance (alcohol, marijuana, cocaine, heroin, hallucinogens, tranquilizers, other pills, or other drugs) participants mentioned (first mention or any mention) when asked the question "at the time when you first started, what did you use?" Most used substances, regardless of whether first mentioned or mentioned at all, were alcohol and marijuana.
The second table depicts mean percentages for the most commonly cited reasons (wanted to fit in with peers, family member/caretaker used, emotional/mental issues, fun/experiment/curiosity, problems at home or school, traumatic, stressful event, wanted to drink/use) participants started using by diagnosis (total, schizophrenia, bipolar, or depression). Overall, the highest percentage of participants said they started using to fit in with peers.
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It is additionally important to investigate reasons for wanting to stop substance use and resources used to attain abstinence in dually-diagnosed individuals, for the purpose of designing more effective interventions in this population. However, this area of study has also been under-researched.
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While the biological and pharmacological factors impacting dual diagnosis have been well investigated, the psychosocial factors impacting it (including substance users' stated reasons for substance use) have not. Following Fishbein's theory of reasoned action, it has been proposed that substance users' personal beliefs about why they use substances may largely determine their substance use behaviors. In particular, dually-diagnosed peoples' perception of the interplay between SMI and SUD may play a major role in their substance use, but this area of study is under-researched.
1. to examine stated reasons for initiation of andrelapse to substance use,2. to examine reasons and strategies used for quit-ting, and3. to explore the perceived association betweensubstance use and mental illness among a largesample of persons with co-occurring SMI andSUD.
The aims of this articleare
Fishbein’s(1980) theory of reasoned action postulates that be-havior is based on attitudes that, in turn, are based onpersonal beliefs. Beliefs rest in large part on what islearnt and experienced; in particular, beliefs that arebased on personal experience have been found tohave a stronger influence in the formation of attitudesthan information gained in other ways and to betterpredict later behavior (Fazio & Zanna, 1981).
The supersensitivity model, wherebybiological vulnerability due to psychiatric disorderresults in sensitivity to small amounts of alcoholand drugs, leading to substance misuse, has alsoreceived some support (e.g., Lieberman, Kane, &Alvir, 1987).
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Several models have been proposed to explain the high rate of comorbidity between SUDs and SMIs. These include family history, ASPD, and the super-sensitivity model. The self-medication model states that specific substances are used to alleviate certain painful affects, but it is not empirically supported. The "alleviation of dysphoria" model is empirically supported, and states that people with SMIs are prone to dysphoric states that predispose them to drug use, which results in them becoming addicted to drugs.
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It is important to better understand causes of substance use in individuals with co-occurring SUDs and SMIs, as the reasons for which they use substances may radically differ from the reasons for which individuals with only SUDs use substances. Increasing our understanding in this area will be important for increasing the effectiveness of therapeutic interventions.
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SUDs have a high rate of co-occurrence with SMIs (severe mental illnesses). Individuals with co-occurring SUD and SMI have a heightened vulnerability to medical, legal, social, and financial problems. Such problems tend to decrease when said individuals attain abstinence and engage in treatment interventions.
The etiology of substance use among persons with severe mental illness remains unclear. Thisstudy investigates stated reasons for substance use among persons in recovery from co-occurringdisorders of serious mental illness and substance abuse and dependence. The desire to fit in withpeers played a key role in the initiation of substance use; boredom, loneliness, temptations to use,and stress were cited most as relapse triggers.
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There are numerous potential reasons as to why it was historically believed that ASD is a protective factor against substance use-related problems. One likely explanation is that substance use in general was less common in the past, so those with ASD were less likely to have substance use-related problems, and research at the time reflected this. Another explanation is that past diagnostic criteria for ASD was narrow and excluded individuals with ASD and substance use-related problems, which also would have been reflected by research at the time.
Increased risk of substance use-related problems seemsto contradict global negative attitudes towards psychoac-tive substances observed among ASD patients (Ramos etal. 2013). Individuals with ASD may find them helpful toreduce tension and enhance social skills more often thannon-ASD controls do (Cludius et al. 2013).
Table 3
Table depicting means (with standard deviations) of proband relatives (full siblings, half siblings, and parents) with various substance use problems (any problem, substance use disorder, alcohol, drugs, tobacco, crime, death, or somatic disease). Also depicts univariate (crude) analyses of the odds ratios (with CIs) for these substance related problems overall, in the presence of a proband with ASD alone, in the presence of a proband with ASD and comorbid ADHD, in the presence of a proband with ASD and comorbid ID, and in the presence of a proband with ASD and comorbid ADHD and ID. Many of the univariate analyses of the odds ratios were statistically significant, meaning that many substance-related problems are significantly likely to occur in relatives of probands with ASD and other comorbid disorders.
Table 2
Table depicting univariate (crude) and multivariate (adjusted for parental age, region of birth, education, and family income) analyses of the odds ratios (with CIs) for various substance use related problems in the presence of ASD comorbid with other conditions (none, ADHD, ID, and ADHD and ID). Univariate and multivariate analyses of the odds ratios were statistically significant for many substance-related problems in the presence ASD by itself, ASD comorbid with ID, and ASD comorbid with ADHD And ID, and for all substance-related problems in the presence of ASD comorbid with ADHD. This means that substance related problems are equally and significantly likely to co-occur in individuals with ASD alone, ASD comorbid with ID, and ASD comorbid with ADHD. They are also more and significantly likely to co occur in individuals in individuals with comorbid ASD and ADHD.
Despite limited and ambiguous empirical data,substance use-related problems have been assumed to berare among patients with autism spectrum disorders (ASD).
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It is widely believed by experts that ASD is not a risk factor for substance use-related problems, but many of the studies that support this assertion compared substance use in people with ASD to substance use in people with other psychiatric conditions that predispose substance use, so their results may have been biased. Another more recent study examined whether ASD traits predispose substance use, but not whether ASD diagnoses does.
We found that ASD was associated with increased risk fora range of substance use-related problems, and the familydata suggested that this was due to shared liability betweenASD and substance use-related problems between relatives.
Table 1
Table depicting the means (with standard deviations) of patients (ASD and non-ASD) with various substance related problems (any problem, substance use disorder, alcohol, drugs, tobacco, crime, somatic disease, or death). Also depicts univariate (crude) and multivariate (adjusted for parental age, region of birth, education, and family income) analyses of the odds ratios (with CIs) for these substance related problems in the presence of ASD. Almost all of the univariate and multivariate analyses of the odds ratios were statistically significant, meaning that almost all of the substance related problems are significantly likely to co-occur with ASD.
Odds ratios (ORs)
A statistic that quantifies the strength of association between two events, A and B. It is the ratio of the odds of A in the presence of B, the odds of A in the absence of B, the odds of B in the presence of A, or the odds of B in the absence of A.
probands
A person that serves as the starting point for a genetic familial study.
We conclude that ASD is arisk factor for substance use-related problems. The elevatedrisks among relatives of probands with ASD suggest sharedfamilial (genetic and/or shared environmental) liability.
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Although substance use is thought to be rare in people with ASD, it has been documented in a significant percentage of that population (19-30%). This may be because there is a high rate of comorbidity between ASD and ADHD, which is linked to substance use. While older studies of clinical populations suggest that ADHD is the risk factor underlying increased substance use in people with ASD, newer studies of non-clinical populations suggest that ASD alone could be a risk factor for increased substance use.
Thus, our research contributes to aburgeoning literature on cross-group friendships by showingthat the positive effects of friendship can extend beyond inter-group attitudes per se to institutional attitudes, and by directlytesting causal links from cross-race friendships to positiveintergroup outcomes (cf. Pettigrew, 1998).
To the extent that a friend’s perceivedmembership in the university in-group is salient, cross-groupfriendship may increase the likelihood that minority-groupstudents will eventually incorporate a university identity as partof themselves.
Therefore, friendships with majority-group peers may be key in the development of dual identityamong minority-group students, and may provide a route towardrelational diversity within institutions of higher education.
Our research underscoresthe importance of the interpersonal climate for addressing issuesof access and diversity within such institutions, and shows thatthe development of affiliative ties across group boundariesprovides an important vehicle for achieving relational diversity.
Together, thefindings of these studies suggest that efforts to increase cross-group friendship are not incompatible with institutional effortsto clearly communicate acceptance of the minority group bysupporting organizations or activities centered on the ethnic orracial background of that group.
This analysisrevealed the predicted three-way interaction, b 5 0.80, F(1, 126)5 6.10, p < .02.
Replicated the finding that minority group individuals with high race-based rejection anxiety having friendships with majority-group peers increased university satisfaction. Additionally, minority group individuals with high race-based rejection anxiety are overall less satisfied with the university than minority group individuals with low race-based rejection anxiety.
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Participants attended three friendship-intervention sessions. For the first two sessions, they asked and answered increasingly personal questions about one another for 45 minutes. For the third session, they played a game of Jenga together and then filled out a questionnaire assessing university satisfaction.
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Participants were informed about the nature of the study, filled out RS-race and RS-personal questionnaires, and then gave their informed consent.
Within 2 weeks of theinformation session, participants were randomly assigned to asame- or cross-group partner, with the restriction that partnersneeded to have compatible schedules.
Participants were randomly assigned to an experimental (cross-group) or control (same-group) condition. The independent variable being manipulated is race of person interacted with (different or the same), and the dependent variable being measured was is university satisfaction.
Over the course of data collec-tion, the ethnic composition of the undergraduate population atthe university was, on average, 34.4% White and 12.0% Latino.Our sample consisted of 76 White participants and 59 Latinoparticipants.
The model for university satisfaction revealed a significant in-teraction between number of majority-group friends and RS-race, b 5 0.46, F(1, 34) 5 7.19, p 5 .01.
Minority group individuals with high race-based rejection anxiety having friendships with majority-group peers decreased dissatisfaction at their university.
The analysis for belonging revealed a significant main effect ofRS-race, b 5 0.25, F(1, 34) 5 6.17, p < .02.
minority group individuals with high race-based rejection anxiety having friendships with majority-group peers decreased lack of belonging.
We specifically addressed thequestion of whether friendships developed with majority-grouppeers over the 1st year of college predicted feelings of belongingin the university 1 to 2 years later, as well as change in satis-faction with the university over this time period.
Study 1 was a 3-year longitudinal study of two cohorts of AfricanAmerican college students at a university where African Amer-icans represented less than 10%, and Whites represented morethan 50%, of the student body over the course of data collection(see Mendoza-Denton et al., 2002).
Given these converging lines of research, we tested whetherfriendships with majority-group peers would buffer minoritystudents who are high in RS-race from feelings of alienation anddiscomfort in historically White university settings.
In a longitudinalstudy of African American students (Study 1), cross-groupfriendships with majority-group peers buffered studentshigh in RS-race from lack of belonging and dissatisfactionat their university. An experimental intervention (Study 2)that induced cross-group friendship replicated the findingsand established their specificity for minority-group stu-dents.
Givenresearch documenting the benefits of cross-group friend-ship for intergroup attitudes, we tested whether friend-ships with majority-group peers would attenuate theeffects of RS-race within these contexts
More specifically, we ex-pected that the development of a cross-group friendship wouldlead to more initiation of intergroup interactions during the diaryperiod, particularly among those who were originally predisposedto anxiety in such interactions. We further hypothesized that par-ticipants higher in RS-race would report more anxious mood overthe diary period but that this anxiety would be attenuated throughthe development of cross-group friendship.
Bringing together the above literatures, we hypothesized thatonly participants who are likely to experience anxiety in intergroupcontexts (either because of RS-race or implicit prejudice) shouldshow signs of hormonal stress responses when they first meet across-group partner, but that cross-group friendship should atten-uate such stress responses over the course of friendship develop-ment. As a corollary, participants who scored lower on measuresof RS-race or implicit prejudice were not expected to show suchattenuation in the cross-group condition because they should havebeen less likely to exhibit hormonal stress responses in the firstplace.
On the one hand, we hypothesized that cortisol reactivityshould be the least pronounced among participants who werepredisposed to anxiety in intergroup contexts but also paired witha cross-group partner with prior intergroup contact. On the otherhand, a series of recent findings have led to an alternate hypothesisthat participants with prior intergroup contact may engendergreater threat among outgroup partners who are vigilant for cues ofrejection in intergroup encounters.
Generally, we propose that cross-group friendship improvesintergroup interactions through systematic disconfirmations ofnegative expectations about intergroup experiences (Mendoza-Denton, Page-Gould, & Pietrzak, 2006).
Zande, 1999), we report a study in which friendship was inducedbetween same- and cross-group dyads of Latinos/as and Whites.
Building on the experimental paradigm used by Wright andcolleagues (Wright et al., 1998, 2002, 2005; Wright & van der
Wright and his colleagues(see Wright, Aron, & Tropp, 2002; Wright, Brody, & Aron, 2005;Wright, Ropp, & Tropp, 1998; Wright & van der Zande, 1999)described research that provided initial evidence for the causaleffects of cross-group friendship on self-reported anxiety.
Even though interactions between members of different socialgroups are sometimes characterized by anxiety and threat (Blas-covich, Mendes, Hunter, Lickel, & Kowai-Bell, 2001; Mendes,Blascovich, Lickel, & Hunter, 2002; Stephan & Stephan, 1985,2000), a growing body of research suggests that cross-groupfriendship can attenuate such anxiety.
These findings provide experimental evidence that cross-group friendship is beneficial forpeople who are likely to experience anxiety in intergroup contexts.
Cross-group friendship led to decreases incortisol reactivity (a hormonal correlate of stress; W. R. Lovallo & T. L. Thomas, 2000) over 3 friendshipmeetings among participants high in race-based rejection sensitivity (R. Mendoza-Denton, G. Downey,V. J. Purdie, A. Davis, & J. Pietrzak, 2002) and participants high in implicit prejudice (A. G. Greenwald,B. A. Nosek, & M. R. Banaji, 2003). Cross-group partners’ prior intergroup contact moderated therelationship between race-based rejection sensitivity and cortisol reactivity. Following the manipulation,participants kept daily diaries of their experiences in an ethnically diverse setting. Implicitly prejudicedparticipants initiated more intergroup interactions during the diary period after making a cross-groupfriend. Participants who had made a cross-group friend reported lower anxious mood during the diaryperiod, which compensated for greater anxious mood among participants high in race-based rejectionsensitivity.
The authors induced cross-group friendship between Latinos/as and Whites to test the effects ofcross-group friendship on anxiety in intergroup contexts.
To address these limitations, in Experiment 1, we requiredparticipants to rate their confidence after each individual response(rather than after each pair of responses).
In Experiment 4, we manipulated participants’ confidence priorto administration of the MRT. All participants first completed aline judgment task that was intentionally difficult, so that par-ticipants would be unable to gauge their performance.
Upon completion of the line judgment task, participants wererandomly informed that their performance on the line judgmenttask was either above average (‘‘high confidence’’condition) orbelow average (‘‘low confidence’’ condition).
Ifconfidence mediates mental rotation performance, then partic-ipants in the high confidence condition should outperform theircounterparts in the low confidence condition.
Cooke-Simpson and Voyer (2007) provided tentative evi-dence that confidence predicted MRT performance, but thatstudy had several critical limitations.
correlation was comparable to that observed in prior studies(r = ?.69; Cooke-Simpson & Voyer, 2007).
As illustrated in Fig. 2, confidence predicted accuracy acrossboth sexes, r(67) = ?.56, p\.001, and the strength of this
Fig. 6
Accuracy percentage as a function of confidence within male and female participants in experiment 3.
Accuracy and confidence were significantly positively correlated for both males and females.
Fig. 5
Accuracy percentage as a function of confidence between male and female participants in Experiment 3.
Accuracy and confidence were significantly positively correlated for both males and females, and females increased their accuracy as a function of confidence more so than males did.
Thisresult replicates the general pattern observed in Experiment 1(Fig. 3), and indicates that both males’ and females’ confi-dence was indeed calibrated to their performance.
Experiment3 therefore supported the hypothesis that mental rotation ismediated by confidence.
Experiment 3 provided a further test of whether the sex differencein performance is better explained by confidence or by omissions.
Results are summarized in Table 1. The sex difference in accu-racy was replicated in the omission condition but not in the com-mission condition.
Thus, the sex difference in mental rotationwas attributable to confidence rather than omissions.
mediates mental rotation. If confidence was unrelated to mentalrotation, then the sex difference should be equivalent acrossgroups (i.e., no interaction should occur).
Critically, an inter-action in either direction would suggest that confidence
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It could also be the case that confidence would have more of an effect on the commission group than the omission group, which would exacerbate the sex difference in MRT performance.
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There were two conditions in this experiment, one in which participants could omit trials at their discretion (omission) and one in which they had to respond to every trial (commission). The idea here was that confidence would have less of an effect on the commission group than the omission group, which would eliminate the sex difference in MRT performance.
In Experiment 2, we sought to attenuate the sex difference inmental rotation performance by rendering confidence irrelevantto the task.
Fig. 4
Shows the mediating relationships between sex, confidence, and mental rotation, via Baron and Kenny's regression method for simple mediation.
Sex negatively predicted both confidence rating and mental rotation score, whereas confidence positively predicted mental rotation score. Confidence seems to mediate the sex difference in MRT performance.
In conclusion, Experiment 1 corroborated the finding thatconfidence predicted mental rotation performance both acrossand within sexes (Cooke-Simpson & Voyer, 2007). Experiment1 further demonstrated, for the first time, that confidence pre-dicted mental rotation performance within individuals: Partic-ipants were more accurate on trials for which they were moreconfident. These results thus provide the most precise evidenceto date of the relation between confidence and mental rotation.Finally, Experiment 1 also provided the first evidence of thedirection of this relationship: Mediation analyses revealed thatconfidence mediated the sex difference in mental rotation per-formance whereas mental rotation performance did not mediatethe sex difference in confidence.
Table 1
Average percentage of problems attempted for males and females in sets 1 and 2 for the 3 minute and 6 minute time conditions in study 2. Significant overall effects are shown for time (3 min or 6 min), test half (set 1 or 2), sex (male or female), interaction between time and sex, and interaction between time and test half.
Percentage of problems attempted was generally higher in the 6 min condition than in the 3 min condition (time difference), in the 2nd set than in the 1st set (practice effect), and for males than for females (sex difference). The interaction effect between time and sex indicates that males attempt more problems than females throughout, but that the difference decreases as more time is given. The interaction effect between time and test half indicates that participants attempt more problems in the second half of the test than in the first half, but that the difference decreases as more time is given.
Table 2
Mean amount of problems solved (with SD) for males and females in the 3 minute and 6 minute time conditions of study 2. Significant main effects are shown for sex (male or female) and time (3 min or 6 min).
Main effect of sex indicates that on average, males solved more problems than females. Main effect of time indicates that on average, participants solved more problems in the 6 min condition than in the 3 min condition.
Fig. 3.
Magnitude of effect size in sex differences as a function of problem position.
Shows that the magnitude of sex difference effect size increased the further subjects got into the set. I.e., the further subjects got into the set, the greater the sex difference in performance was (males outperformed females).
Fig. 1.
The figures that are shown in the Vandenburg and Kuse MRT. The target stimulus is the leftmost stimulus shown here. Two of the stimuli to the left of the target figure are rotated versions of the target figure, and two of them are distractor figures. Participants had to identify which figures were rotated versions of the target figure.
Fig. 2.
Percentage of problems attempted as a function of problem position for males and females in the first and second sets of study 1.
Both males and females would attempt less problems the further they got in the set, but this effect was greater for females than for males. Also, both males and females attempted more problems the further they got in the second set than in the first set, revealing a practice effect.
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Varying the amount of stimuli presented to the participants in the MRT could reveal sex differences as a result of women spending more time making sure that their MRT answers are correct than men do.