CNP VCAP

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Basic Task Description

This task was designed by Ty Cannon and David Glahn as a verbal analogue to the SCAP (spatial capacity task). It has been run in a number of local samples, including Aftercare (first episode), ABBRC (adolescent psychosis), CAPPS (prodromal), and NF1 (neurofibromatosis).

This task manipulates verbal working memory load using arrays of letters. The loads are selected to be behaviorally analogous to the CNP_SCAP loads.

Loads: 3,5,7,9 letters

Text
We employed a modified Sternberg item recognition task (Sternberg, 1966 S. Sternberg, High-speed scanning in human memory, Science 153 (1966), pp. 652–654. View Record in Scopus | Cited By in Scopus (758)Sternberg, 1966). A target set of 3, 5, 7, or 9 yellow uppercase consonants was displayed for 2 s, followed by a 3-s fixation. A green uppercase probe then appeared for 3 s, followed by 1 s of fixation before the next trial. Subjects indicated whether the probe matched the target set. The task included 12 trials per load, which were clustered by load into two-trial long blocks; presentation order of the blocks was counterbalanced, but remained the same for all subjects.
Karlsgodt, 2007

Task Procedure

Task Structure Detail

There are 12 trials per load, the trials are blocked in sets of 2 and analyzed in those blocks.

Trial layout:
1. fixation for 1 second
2. target array (multiple uppercase letters) for 2 seconds
3. delay period (fixation) for 3 seconds
4. probe array (single lowercase letter) for 3 seconds.

Each trial lasts 9 seconds, the TR=3seconds, there are 180 TRs making the task 9 minutes long.

Task Schematic

Vcap bigschematic.jpg

Task Parameters Table

Stimuli

Dependent Variables

Cleaning Rules

Code/Algorithms

Data Distributions

References

Karlsgodt, 2009, Schizophrenia Research
Sanz, 2009, Psychiatry Research
Karlsgodt, 2008, Biological Psychiatry