Visual search irregularities in schizophrenia depend on display size switching.
BACKGROUND
In past research it has been demonstrated that when performing a visual search task with either one or multiple (4, 7 or 10) stimuli displayed, patients with schizophrenia demonstrate slow response times (RTs) in the display size of one, target-absent (one-absent) condition. The goals of the present investigation were to replicate this effect, and to gain an understanding of the underlying cognitive operations by comparing display-size switch to display-size repeat trials.


METHODS
In two experiments, patients and controls performed a visual search task with either one or four stimuli displayed. In Experiment 1 (one block with mixed switch and repeat trials), RT for display-size switch trials was compared to RT from display-size repeat trials. In Experiment 2, the display-size one and display-size four conditions were run in separate, homogeneous blocks.


RESULTS
The results demonstrate that the one-absent slowing effect was eliminated on repeat trials, regardless of whether the switch and repeat trials were mixed or presented in separate blocks.


CONCLUSIONS
This set of results suggests that a combination of cueing and switching effects may underlie the one-absent slowing observed in patients, such that switching to the one-absent condition is difficult due to insufficient cueing of the relevant cognitive operations. This visual search paradigm is an excellent candidate for inclusion in the development of a neurocognitive profile specific to schizophrenia.
Simon Fraser University, Burnaby, Canada. twoodward@psych.ubc.ca
Todd S
TS
Woodward
Jennifer C
JC
Whitman
Katherine
K
Arbuthnott
Tonya L
TL
Kragelj
Jessica
J
Lyons
Emmanuel
E
Stip