This is PEBL's implementation of the Item-Order test from the Unified Tri-Services Cognitive Performance Assessment Battery (UTCPAB; see Perez, Masline, Ramsey, and Urban, 1987) that explicitly tests item and order information, in the context of a same-different test.
As described by Perez et al., this is how a trial works:
1. A 7-consonant string is presented for 2.5 sec. 2. It disappears for 2 seconds. 3. A new string appears, and the subject must judge same/different by hitting a key.
Stimuli are either the same (20 trials), have a letter substituted (10 trials), or have a pair of adjacent letters swapped. So, you might see:
and two seconds later, see:
Change whether you get correct/incorrect feedback by setting gFeedback to 0 or 1:
gFeedback <- 1
The character set used can be changed by altering this line:
gLetters <- SubList(FileReadList("Consonants.txt"),1,21)
You need at least 8 letters.
 Data Output
Data are stored in itemorder-<gsubnum>.txt. Columns are as follows:
subnum trial type inputstring comparison position response correct absolute_time rt
9 1 0 LDJFTBN LDJFTBN 0 <lshift> 1 7052 803 9 2 0 FTNHKSL FTNHKSL 0 <lshift> 1 13737 557 9 3 1 KQBGTFW KJBGTFW 1 <rshift> 1 20179 466 9 4 2 DJXLMHK DJLXMHK 3 <rshift> 1 26534 527
The column headers are not saved in the file, so you can more easily concatenate multiple subject data files. the column 'type' determines whether the trial will be 'same' (0), 'item' (1), or 'order' (2) the column 'position' specifies where the change occurred; for order tests, it specifies the position of the first swapped character.
In general, the time for the task increases as the change gets later in the list. Example results from the test:
Perez, W. A., Masline, P. J., Ramsey, E. G. and Urban, K. E. (1987). Unified Tri-services cognitive performance assessment battery: Review and methodology, DTIC Document ADA181697.http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA181697