On 2016 Dec 17, Lydia Maniatis commented:

While the title of this article refers to perception, the term is used loosely. The authors are not examining the process or principles via which a percept is formed, but, rather, how certain already-formed features of that percept are used to identify and label various substances whose general appearance is only one, and sometimes not even the most important, characteristic normally used to identify the substance. The question seems trivial and essentially non-perceptual.

An excerpt from the concluding paragraph of the paper may help convey the level of the conceptual discussion:

“…the name “chocolate” is assigned to all viscosities as long as the optical material is chocolate. This presumably reflects the fact that different concentrations and temperatures of chocolate yield a wide range of viscosities, but changes to the surface color and optical appearance are less common… The term “water” specifies a specific colorless transparent appearance and a specific (runny) viscosity. “

What does it mean to say that “the optical material is chocolate.” It seems like just a jargony way of saying “the name chocolate is assigned to anything that looks like chocolate” which begs the (trivial) question, and which isn’t even necessarily true, since the dispositive feature of chocolate is the flavor. Similarly, how do the authors distinguish between the label "water" and the labels "alcohol," "white vinegar," "salt solution" etc?

The distinction the authors are making between “optical” and “mechanical” properties indicates they haven’t understood the problem of perception. It’s not clear what distinction they are making between “optical appearance” and simply "appearance." In the category of “optical” characteristics they place color, transparency, gloss, etc. But color, transparency, gloss as experienced by observers are perceptual characteristics, and as such are in exactly the same category as perceived “mechanical” characteristics, among which the authors place perceived viscosity.

That the distinction they are making is a perceptual one is in no doubt as they are using images as stimuli, i.e. stimuli whose perceived "optical and mechanical" properties differ greatly from their physical properties. Even if they were using actual objects, the objection would be the same, as the actual stimulus would be the retinal projection, which contains neither color, viscosity, etc.

It is also inexplicable to me why the authors would refer to “optical appearance” as equivalent to “low-level image correlates.” Converting a retinal projection into a percept containing features such as transparency or color or gloss requires the very highest level of visual processes.

All in all, the article conveys conceptual confusion about the basic problem of perception, let alone how it is achieved, while the problem chosen for study doesn’t touch on any of these problems or solutions.

On 2016 Dec 17, Lydia Maniatis commented:

While the title of this article refers to perception, the term is used loosely. The authors are not examining the process or principles via which a percept is formed, but, rather, how certain already-formed features of that percept are used to identify and label various substances whose general appearance is only one, and sometimes not even the most important, characteristic normally used to identify the substance. The question seems trivial and essentially non-perceptual.

An excerpt from the concluding paragraph of the paper may help convey the level of the conceptual discussion:

“…the name “chocolate” is assigned to all viscosities as long as the optical material is chocolate. This presumably reflects the fact that different concentrations and temperatures of chocolate yield a wide range of viscosities, but changes to the surface color and optical appearance are less common… The term “water” specifies a specific colorless transparent appearance and a specific (runny) viscosity. “

What does it mean to say that “the optical material is chocolate.” It seems like just a jargony way of saying “the name chocolate is assigned to anything that looks like chocolate” which begs the (trivial) question, and which isn’t even necessarily true, since the dispositive feature of chocolate is the flavor. Similarly, how do the authors distinguish between the label "water" and the labels "alcohol," "white vinegar," "salt solution" etc?

The distinction the authors are making between “optical” and “mechanical” properties indicates they haven’t understood the problem of perception. It’s not clear what distinction they are making between “optical appearance” and simply "appearance." In the category of “optical” characteristics they place color, transparency, gloss, etc. But color, transparency, gloss as experienced by observers are perceptual characteristics, and as such are in exactly the same category as perceived “mechanical” characteristics, among which the authors place perceived viscosity.

That the distinction they are making is a perceptual one is in no doubt as they are using images as stimuli, i.e. stimuli whose perceived "optical and mechanical" properties differ greatly from their physical properties. Even if they were using actual objects, the objection would be the same, as the actual stimulus would be the retinal projection, which contains neither color, viscosity, etc.

It is also inexplicable to me why the authors would refer to “optical appearance” as equivalent to “low-level image correlates.” Converting a retinal projection into a percept containing features such as transparency or color or gloss requires the very highest level of visual processes.

All in all, the article conveys conceptual confusion about the basic problem of perception, let alone how it is achieved, while the problem chosen for study doesn’t touch on any of these problems or solutions.