Stimulus Onset Modulates Auditory and Visual Dominance

Round 1

Reviewer 1 Report

The article presents two experiments on sensory (visual vs. auditory) dominance in perceptual judgments. In line with previous work by Robinson and colleagues, the time between visual and auditory information and the task (1 vs. 3 buttons) were manipulated to analyze whether the visual dominance usually obtained in the so called Colavita effect is not observed, under certain circumstances. The study seems to be conducted very rigorously and the methodology looks more than adequate to answer the questions posed by the authors. The manuscript is well written and, in my opinion, does not need excessive revision. Please find further (perhaps more theoretical than methodological) comments below.

A relevant aspect for this work that could be discussed in more detail (perhaps linked to previous works by Robinson and collaborators) is the purely physiological difference in time of arrival at sensory cortex between the auditory input (which is faster) and the visual input. I think it is important to strengthen the relevance of this neural explanation as it may help to understand the results obtained in single button tasks.

The literature on the temporal aspects of multisensory integration (and, especially, audiovisual integration) indicates that the stimuli that fall within a certain asymmetric temporal window are integrated to produce a single percept. Note that we tolerate more asynchrony when vision leads in time. The authors briefly mention this at the end of the Discussion. Among all of the SOAs used by the authors, some fall within this window for multisensory integration and some others do not. I wonder if the theory of sensory dominance, in which the inputs of different modalities compete, in a "race for processing resources" (as the authors say, p. 11), fits with this previous body of work or not.

When we perceive a multisensory event occurring at a certain distance from us, the visual information comes before the auditory (as that light travels much faster than sound). Therefore, the visual input is the one that provides, in many cases, more precise information about the moment in which a distant event has happened. The fact that visual information arrives earlier to us may perhaps generate a “processing bias”, so we trust this information when it provides us with sufficient details about the event in question. I wonder if this, together with the visual superiority also in the spatial domain, will contribute to visual dominance. Given that one of the main experimental manipulations introduced the present work involved time, I wonder if the authors should discuss these issues in more detail.

A minor issue: I would perhaps mention the “conceptual” differences between the 1-button and the 3-buttons task in the abstract.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper investigated sensory dominance in two experiments using an oddball task, and found evidence in support of the claim that the first (sensory) modality that is processed, is the one that dominates the other. In particular, the authors found that the auditory modality tends to “win” this race, as this modality may possess intrinsic features that favour it at earlier stages of perceptual processing.

 

Overall, I find the study interesting, although some work should be done especially in the introduction section. Below I list some concerns.

 

Abstract:

1) The first sentence should be rephrased. Consider simply erasing the last part of the sentence, which sounds redundant and weird (“with strong evidence over the past few decades suggesting that the visual modality is more dominant”).

2) Consider changing the second sentence into: “However, this visual dominance effect can be reversed under some conditions, favouring auditory dominance”.

 

Introduction:

1) In general, please check the English. There are typos and mistakes throughout the manuscript. For example, Introduction, line 36: arriving TO separate senses. Line 62: remove AS from ‘rather than as a…’

2) Lines 40-42: The sentence is misleading, as it ‘announces’ that you will discuss exceptions of visual dominance, but then you quote the Colavita effect immediately after, which is a case of visual dominance.

3) Lines 62-65: not clear to me what you mean with this sentence. In the study by Koppen and Spence, the authors showed that within the temporal window of (multisensory) integration, participants favour the visual over the auditory modality, and this is even stronger when the visual stimulus is presented first.

4) I’m not sure I get the hypotheses formulated by the authors. First, it would be useful to the reader to understand why these sensory dominances are interesting to study at all. Second, your hypotheses should be explained a bit better. For example, simply stating that in the 1-button task you expect that the stimulus presented first would show dominance does not really tell why you think so. And why should the auditory stimulus ‘win’ in the synchronous condition? I guess it’s a matter of attention, but it needs some extra rationale.

Same for the second hypothesis: how do you define decision making here? I guess you believe it has a different time course with respect to perceptual processing, i.e., sensory processing first, decision-making second; but why should it overwrite the early processing of stimuli? You’re treating decision making as if it were an agent, and this is weird. In relation to this, I also don’t understand why you expect the ‘agent’ decision-making to be visual. Please re-write this part to make it a LOT clearer.

 

Method:

I suggest that the authors keep together the method section that pertains to single experiment; so, for instance, participants, stimuli, procedure and even results of exp 1 together, and then pass to the description of exp 2.

As for the results, did you correct the t-tests?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf