Can rhythm-induced attention improve the perceptual representation?

Temporal attention can be entrained exogenously to rhythms. Indeed, faster and more accurate responses were previously found when the target appeared in-phase with a preceding rhythm in comparison to when it was out of phase. However, the nature of this rhythm-induced attentional effect is not well understood. To better understand the processes underlying rhythm-induced attention, we employed a continuous measure of perceived orientation and a mixture-model analysis. A trial in our study started with a sequence of auditory beeps separated by a fixed inter-beeps interval in the regular (rhythmic) condition or by variable inter-beeps intervals in the irregular condition. A visual target–a line embedded in a circle–followed the sequence. The ‘critical’ interval between the last beep and the target was chosen randomly from several possible Inter-Onset Intervals (IOIs), of which only one was in-phase with the rhythm. The target was followed by a probe line, and the participants were asked to rotate it to reproduce the target’s orientation. The measure of performance for a given trial was the difference in degrees between the orientation of the target and that reproduced by the observer. We found that guessing rate was lower with regular than irregular rhythms. However, there was no effect of rhythm type (regular vs irregular) on the quality of representation (measured as the variability in reproducing the target). Furthermore, the rhythm effect was present only when rhythm type was fixed within a block, and it was found with all IOIs, not just the in-phase IOI. This lack of specificity suggests that these results reflect a general effect of rhythm on alertness.


Response:
We apologize for not being clear enough. We now explain in the text that the g parameter (which is the height of the uniform distribution) reflects the proportion of trials, out of the total number of trials, in which the participant provided a random response (p. 5). Thus, if g=0.2 this means that on 20% of the trials the error is due to guessing. Comment: Line 130: "data was" -should be "were" Response: Fixed. Comment: Also, I'm a little uncomfortable with excluding data based on model convergence failure. Is there a more empirical performance-based measure that you can use to exclude data? Same issue for Experiment 3.

Response:
A model failure to 'converge' means that the fitting procedure could not find model's parameters that provide good-enough fit to the data, and therefore aborted without providing parameters for the data. Because we are running the statistical analysis on these parameters, without parameters we cannot include the participants. It's similar to excluding participants who drop from the experiment before the end -if we don't have data for them, we cannot include them. We elaborated the explanation that was already provided in the original version to ensure it is now clear (p. 7) Comment: Line 173: delete "a" at end of line

Response: Fixed
Comment: Line 223: this is quite a different IOI than Experiment 1, and much closer to the average spontaneous tapping rate (thus potentially making entrainment easier). Might be worth adding some justification of this design choice.

Response:
We agree and we added this to the manuscript (p. 10-11) Comment: Line 396: "examined" -should be present tense

Reviewer #2:
In this study, the authors investigated whether entrainment to rhythms can modulate the quality of sensory representation. This is a nicely written paper with interesting results. I do not have any comments on the proposed experiments or analysis. However, I believe it is important for authors to complement their discussion with the following points: Comment: 1) Can the task be influencing the results? As authors point out, the majority of results in entrainment use simple tasks, such as detection or discrimination tasks. Possibly, in the task authors used, the effect of entrainment can be smaller or even inexistent.

Response:
We do not see how the task we have used could prevent the emergence of attentional entrainment to the rhythm. On the contrary, attentional effects are typically larger with more complex tasks. Comment: 2) Whether the task can be too hard or too easy. The pattern of results suggests that participants are performing the task very well, with SD around 13 degrees. Could that be a possible reason for the lack of effects?

Response:
The reviewer is only considering here 1 type of errors -errors that reflect a nonprecise encoding of the target. But there are also trials in which the participants are completely guessing. In Experiments 2 and 3 guessing rate was about 15% and 20 %, respectively. So, in addition to these trials, on trials in which they were not completely guessing (i.e., on the remaining 85% and 80% trials, respectively) they made errors with SD of about 13 deg. This leaves plenty of room for improvement due to entrainment, yet no such improvement was found.

Reviewer #3:
The current study investigated in three behavioural experiments, the influence of auditory rhythmic stimulation on visual perception. In all three experiments the authors compared the influence of a regular/irregular auditory sequence on visual target performance. While a blocked design employed in experiment 2 and 3 enhanced performance for rhythmic sequences, none of the three studies found an effect of in-phase target presentation. Overall the methods are sound and the manuscript is well written. However, every so often there is a bit of clarification needed. Further, sometimes the motivation for the chosen parameters is not clear. Comments and suggestions are roughly listed in order of appearance within the manuscript Major comments: Comment: The introduction mainly focuses on attentional or neural entrainment studies in uni-modal, either auditory or visual, contexts. However, the task used in the current study is essentially a cross-modal task. It would be good to have some explicit motivation in the introduction for why an auditory rhythm should have an influence on visual target perception and in this study on visual working memory. Further, there are a few papers on cross-modal rhythms, which could be mentioned in the introduction, such as: Miller et al., 2013: When What You Hear Influences When You See: Listening to an Auditory Rhythm Influences the Temporal Allocation of Visual Attention. Psychological Science, 24, 11-18. Escoffier, N. et al. (2015) Auditory rhythms entrain visual processes in the human brain: Evidence from evoked oscillations and event-related potentials. Neuroimage 111, 267-276. Barnhart, A.S. et al. (2018) Cross-modal attentional entrainment: Insights from magicians. Attention, Perception, Psychophysics. 80, 1240-1249. Response: We added to the Introduction section a more elaborated description of the motivation for using a cross-modal design and we now refer to previous cross-modal studies (p. 5-6)