'Phase dependence of auditory perception'
(AsPredicted #57927)
Author(s)
This pre-registration is currently anonymous to enable blind peer-review.
It has 3 authors.
Pre-registered on
02/10/2021 04:12 AM (PT)
1) Have any data been collected for this study already?No, no data have been collected for this study yet.
2) What's the main question being asked or hypothesis being tested in this study? Studies using a type of brain stimulation called transcranial alternating stimulation (tACS) suggest that multiple sinusoidal oscillations produce ‘phase effects’. For example, Neuling, Rach, Wolters, and Herrmann (2012) stimulated participants with alpha, and they show that the behavioural results could be explained with a sine fit to the stimulated frequency; partcipants were better able to detect near threshold tones in noise when the tones were presented in the positive half wave of stimulation, compared with the negative half wave or Sham, where there was no stimulation. Riecke, Formisano, Herrmann, and Sack (2015) found similar results when participants were stimulated with delta (4 Hz) and detected near threshold click trains.
As stimulation with two different sine waves produced similar effects, we ask whether perception of near threshold tones depends on the phase of alpha, delta, or polarity (independent of sine wave modulation). If perception depends on the polarity of the stimulated signal, rather than a specific sine wave, participants would be able to detect better near threshold tones in noise in the positive than the negative half of the stimulated current across all stimulation conditions.
3) Describe the key dependent variable(s) specifying how they will be measured. The dependent variables are the percentages of near threshold tones detected in: each of the six phase bins of the stimulated sine waves (alpha and delta); the postive and negative direct current stimulation; total number of trials in the control condition (SHAM stimulation), and percentage of tones detected in 'catch trials' where no tone was presented (i.e., false alarms).
4) How many and which conditions will participants be assigned to? This is a within subjects design with four conditions. In each condition, participants will be stimulated with one of three types of brain stimulation (alpha, delta, and direct-current) or SHAM, which is a control condition in which participants are stimulated for 30 seconds at the start of the experiment and no stimulation for the rest of the time.
The order of the conditions will be counterbalanced between the participants, and order effects will be examined in the analysis.
5) Specify exactly which analyses you will conduct to examine the main question/hypothesis. We will conduct a permutation based analysis with a logistic regression (as described in Zoefel, Davis, Valente, & Riecke, 2019). This involves permuting the responses for single trials by assigning them to different phase bins, and calculating the detection percentages in the positive and negative bins in each permutation. The frequency of the detection difference will then be plotted to create a surrogate distribution based on the data. The original difference in detection between positive (bins), and negative (bins) will be located on the surrogate distribution and the z score will be calculated. The effect will be considered significant if the z score is >= 1.645, which is equal α = 0.05.
6) Describe exactly how outliers will be defined and handled, and your precise rule(s) for excluding observations. Volunteers with implanted biomedical devices, or those who take certain medications (antipsychotics, antidepressants, benzodiazepines, L-dopa) will not be able to participate as these factors can influence the effects of the stimulation (Brandt et al., 2007; Utz et al.2010).
Volunteers with a history of migraine or epilepsy, or hearing impairments will also be excluded from this study.
7) How many observations will be collected or what will determine sample size?
No need to justify decision, but be precise about exactly how the number will be determined. Data from 20 participants will be collected for this study.
8) Anything else you would like to pre-register?
(e.g., secondary analyses, variables collected for exploratory purposes, unusual analyses planned?) In addition to the main analysis, we will conduct a parametric alignment based analysis in order to compare our results with previous study (Neuling et al., 2012). This will involve aligning the behavioural data to the zero crossing (180), and conducting two repeated measures ANOVAs: 3 (stimulation type) x 2 (wave polarity), and 2 (sinewave) x 5 (phase bins). The phase bin used for alignment is excluded (see Asamoah, Khatoun, & Laughlin, 2019, for further details). Then sine fits will be performed where the null hypothesis would be a horizontal line (i.e., no modulation by phase/polarity).
We will also record EEG data for 5 mintues before and after the main task. During this time, participants will be asked to respond to a cross that rotates on the screen. Accuracy in the task will be used to determine how attentive participants were during these tasks. We will compute the power of endogenous neural oscillations to examine whether the power of the stimulated frequency increases in the post-task EEG measurement. We will also correlate the magnitude of the power increase to the differences in detection percentages between positive and negative bins.
Version of AsPredicted Questions: 2.00