Interocular Differences in Spatial Frequency Influence the Pulfrich Effect

Round 1

Reviewer 1 Report

This paper describes an experiment for testing between two possible explanations of the Pulfrich effect - an apparent in depth motion where the stimulus is in the plane perpendicular to the line of sight - an explanation involving spatial frequency and an explanation involving interocular size. The experimental results favor the spatial frequency explanation and appear to be well supported by the experiment. This is important since it helps to clarify mechanisms used in neural processing prior to the reconstruction in phenomenal visual space, and thus further supports the overwhelming evidence that visual experience is the result of an indirect reconstruction of what is likely going on with a physical distal object and not a direct presentation of aspects of that object per se.

There were some minor problems with the writing of the paper:

line 56 it might help to either define or give a reference to "Gabor elements" since some readers may not be familiar with them.

lines 199 and 204 the article 'the' should precede PSE

line 277 perhaps 'would' should be substituted for 'could'

line 298 a noun is missing after 'overall'

line 309 'induced' should be substituted for 'induce'

line 315 'differences' should be substituted for 'difference'

line 320 'is' should be substituted for 'are'

line 363 the conclusion appears to be stated incorrectly. If this is correct 'not' should be inserted after 'does.'

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

General comment: it is not clear for how long the stimuli were visible and where the subjects fixated.

Specific comments:

- line 98: “sinusoidal profile of 18 deg/s” is ambiguous. If it is sinusoidal, then the speed is variable. Better to be explicit and specify the 18 deg/s as the amplitude of the sinusoid.

- line 100 and 103: better again clarify that the size parameter is the sigma parameter of the Gabor to avoid confusion. Similarly for Fig. 2 legend.

- line 136: the last sentence of the figure legend is incomplete and very confusing.

- line 109: there’s a reference to Fig. 3b, but Fig. 3b has a lot more going than what is meant by this reference. As a result, the reader is confused. For example, the figure shows dB values that were never defined etc. very confusing. Better maybe show a simple psychometric curve just to illustrate the analysis (for the 0dB case), and then a later figure in results shows the results of the spatial frequency and size manipulations.

- paragraph of line 144: I don’t know why Results are shown in the methods section. Feels inappropriate.

- line 155: two sentences are not separated by a full stop.

- line 159: related to the above comments about results in the methods section, this paragraph is perfect illustration of the problem. Figure 3b and the text above were using dB as a measure that only gets defined here! Very confusing.

- line 298: missing word at end

- paragraph of line 295: I missed where the authors reported on perceptual fusion in the whole paper??? They discuss it here, but how do the results demonstrate that there was binocular fusion???

Author Response

Please see the attachment.

Author Response File: Author Response.docx