On 2016 Oct 31, Lydia Maniatis commented:

I think the authors have overlooked a major confound in their stimuli. This is the structure of the collection of items. If we have three items, for example, they will always form a triangular structure, except if they’re in a line. If they’re in a line, they still have a structure, with a middle and two flanking items. Our visual system is sensitive to structure, including that of a collection of items; Gestalt experiments have also shown this is also clearly the case with much “lower” animals, such as birds. I don’t think the authors can discuss this issue meaningfully without taking this factor into account.

On 2016 Oct 31, Lydia Maniatis commented:

I think the authors have overlooked a major confound in their stimuli. This is the structure of the collection of items. If we have three items, for example, they will always form a triangular structure, except if they’re in a line. If they’re in a line, they still have a structure, with a middle and two flanking items. Our visual system is sensitive to structure, including that of a collection of items; Gestalt experiments have also shown this is also clearly the case with much “lower” animals, such as birds. I don’t think the authors can discuss this issue meaningfully without taking this factor into account.