We treated the rating task as a multiple yes/no detection task: For each observer, and for each coherence and urgency condition, we calculated hits (on signal trials: coherent motion) and false alarms (on noise trials: coherence = 0%) over four response combinations.
The response amplitudes were largest at 20 Hz (beta) and significantly reduced at 40 Hz and 60 Hz (gamma), although synchronization strength, indicated by inter-trial coherence (ITC), did not substantially differ between 20 Hz and 40 Hz.
The time frequency analysis was based on wavelet and two characteristic parameters of event-related spectral perturbation (ERSP) and inter-trial coherence (ITC) were computed to indicate the evoked response (time-locked) and phase reset (phase-locked) activity, respectively.
Inter-trial Coherence of Medial Frontal Theta Oscillations Linked to Differential Feedback Processing in High-Functioning Autism.
We found that at fronto-central electrodes, inter-trial coherence at all frequencies tended to increase with age.
Inter-trial coherence of Ta showed no evidence of increase with age at low frequencies, instead showing a tendency to decline at electrode T8.
Time-frequency analysis was then conducted on the specified channels to measure inter-trial coherence (ITC) and event-related spectral perturbation (ERSP).
Here we focus on two complementary indices: (i) inter-trial coherence (ITC), a measure of the extent to which phase-locking occurs, and (ii) event-related spectral perturbation (ERSP), a measure of the increase in power in a frequency band after presentation of a signal, relative to baseline.
For the remaining 180 trials, coherence was randomly chosen as either this 'high coherence' value (25% of trials) or a 'low-coherence' value (75% of trials).
Figure 2 shows schematically the experiment design: on each trial, the coherence of the Glass pattern increased linearly from zero to 100% over 100 ms, remained at 100% coherence for 300 ms, then decreased linearly to zero over 100 ms. The ISI varied between 3000 and 3200 ms, during which time the Glass pattern had zero coherence.
Accuracy levels for the easy trials (20%and40%40 % coherence) were higher for the visual than for the auditory task (note that the 80 %-coherence trials were discarded from the DDM analyses, as participants made very few incorrect choices for this stimulus strength).
