PEBL Perceptual Vigilance Task
Simple reaction time task--an circle stimulus appears at delays between 2 and 12 seconds, and the participant must depress the spacebar as quickly as possible. This is basically the simple RT task, but a version commonly used to measure sleepiness and arousal.
It follows the procedure described by Wilkinson fairly reasonably, with several exceptions.
- As with the Wilkinson device numeric feedback is given; however unlike that device a running counter is not displayed. The presence of feedback can be controlled with the variable giveFeedback.
- There are three different types of testing to choose from to determine whether the experiment is complete: time-based, trial-based, and block-based. These are controlled by the testType variable (1, 2, or 3)
- Time-based will run until a certain time has elapsed
- Trial-based will run until a specific number of trials have completed
- Block-based allows one to use an isi-block, which gets sampled from without replacement, and then reshuffled until the number of blocks has elapsed
- In addition, when the useContinuous variable==1, it will choose a continuous stimulus presentation time between the min and max of timeInterval. Otherwise, it will sample from the set in timeIntervals
By editing script, one can specify aspects of the task: Number of trials, total test duration, isis
 Data Output
Data is saved to file ppvt-<gsubnum>.txt. Columns are:
SubjectNum, Block, Trial, ISI, isibin, absolute_Time, RT, response_type
Example data file looks like this:
sub,block,trial,ISI,ISIbin,abstime,rt,type 33,1,1,9106.74,9000,6404,526,3 33,1,2,8029.24,8000,18446,10776,3 33,1,3,9109.36,9000,39664,620,3 33,1,4,8439.79,8000,51801,-5986,1
- sub is the subject code
- block indicates the block of trials. By default there are 12 blocks, with 120 trials each.
- trial is the overall trial counter (stimulus order) of the experiment
- ISI is the inter-stimulus interval--the time since the previous stimulus
- ISIbin rounds ISI to the nearest second (using floor)
- abstime is the start-time of the trial. This is recorded in ms since the start of the experiment.
- rt is the response time to the stimulus. A negative value indicates a too-fast result; it is recorded as the RT to the beginning of the trial, not the time prior to the stimulus that the response would have been given.
- type is a response categorization. for trial type, 1=too fast, 2= OK, 3 = lapse (> 500 ms) 4 = sleep (>30 s)
A summary of the results, with means and standard deviations across delays, is output to ppvt-report-<gsubnum>.txt.
Wilkinson, R. T., & Houghton, D. (1982). Field test of arousal: A portable reaction timer with data storage. Human Factors, 24, 487-493.
Dinges, D. F., & Powell, J. W. (1985). Microcomputer analyses of performance on a portable, simple visual RT task during sustained operations. Behavior Research Methods, Instruments, & Computers, 17, 652-655.
 Research using PEBL PPVT:
Karlen, W., Cardin, S., Thalmann, D., & Floreano, D. (2010). Enhancing pilot performance with a SymBodic system. In Engineering in Medicine and Biology Society (EMBC), 2010 Annual International Conference of the IEEE (pp. 6599-6602). IEEE. http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5627127