On 2016 Jun 17, Lydia Maniatis commented:

(This is a response to the abstract only). The authors conclude that perception of distance ratios is relatively accurate, but this result is purely contingent on the stimuli. Perception of relative distances can be more or less accurate. The outcome depends strictly on the structure of the retinal stimulus and the rules of organisation built into the visual system. By choosing a particular physical stimulus to project to the retina, the authors produced relatively accurate outcomes; by choosing a different one, they could have produced very different outcomes. Pictorial images, for example, can obviously produce very inaccurate perception of relative distances. Unless the authors explicitly discuss the relationship between the structure of the environment and the structure of the retinal projection, they haven't added anything to the conversation.

On 2016 Jun 17, Lydia Maniatis commented:

(This is a response to the abstract only). The authors conclude that perception of distance ratios is relatively accurate, but this result is purely contingent on the stimuli. Perception of relative distances can be more or less accurate. The outcome depends strictly on the structure of the retinal stimulus and the rules of organisation built into the visual system. By choosing a particular physical stimulus to project to the retina, the authors produced relatively accurate outcomes; by choosing a different one, they could have produced very different outcomes. Pictorial images, for example, can obviously produce very inaccurate perception of relative distances. Unless the authors explicitly discuss the relationship between the structure of the environment and the structure of the retinal projection, they haven't added anything to the conversation.