PEBL Continuous Performance Test
The pcpt directory of the test battery offers two related continuous performance tasks. The pcpt.pbl task is a faithful implementation of Conners's Continuous Performance task (CCPT). A constant series of letter stimuli appear on the screen; participant must respond to all stimuli EXCEPT the X. The pcpt-ax.pbl is an implementation of the CPT-AX task, modeled after one used by Lee and Park (2006). In this task a response is made ONLY when X follows A.
This is a vigilance task, which takes approx 14 minutes to complete. 360 letters approx 1 inch in size are presented one at a time. Participant must respond by pressing the space bar to all stimuli except the X.
Located in battery/pcpt/pcpt.pbl x
The default parameters reflect the Connors task faithfully.
- testtype (Default=1) Type of test. Currently, only type 1 is implemented.
- cycles (Default=6). Total number of blocks. cyclesxblocksize is the number of trials
- blocksize (Default=20). Number of trials per block
- prestime (Default=250). Presentation time of stimuli
- targprob (Default=0.1). Probability of an 'x' target being presented
- givefeedback (Default=0). Give text-based feedback about
- pausebetweenblocks (Default=0). Whether a pause should occur between each ISI block
- proportionalfoil (Default=1). if set to 1, will use exactly 1-targprob foils; if set to 0, will generate a foil with 1-targfoil probability on each trial
- cycles (Default=6) Total number of blocks. cyclesxblocksize is the number of trials
- blocksize (Default=20) Number of trials per block
- isi (Default=5000) Time between stimuli
- prestime (Default=250) Presentation time of stimuli
- axprob (Default=0.7) probability of a AX trial.
- bxprob (Default=0.1) probability of a BX trial
- ayprob (Default=0.1) probability of a AY trial
- byprob (Default=0.1) probability of a BY trial
- givefeedback (Default=0) Whether to give error feedback
- pausebetweenblocks (Default=0) should they pause between blocks of trials?
Detailed data is stored in data/subnum/ptpt-subnum.csv, and pooled across subjects in data/pooled-pcpt.csv. Detailed summary report is in data/subnum/pcpt-report-subnum.txt. This contains a number of summary statistics broken down across ISI. For cpt-ax, identical files named pcpt-ax are saved.
C. Keith Conners, Jeffery N. Epstein, Adrian Angold, John Klaric (2003) Continuous performance test performance in a normative epidemiological sample Journal of Abnormal Child Psychology,
- Lee, J. & Park, S. (2006). The role of stimulus saliance in CPT-AX performance of schizophrenia patients. Schizophrenia research, 81, 191-197.