CNTRICS final task selection: control of attention

Abstract

The construct of attention has many facets that have been examined in human and animal research and in healthy and psychiatrically disordered conditions. The Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) group concluded that control of attention-the processes that guide selection of task-relevant inputs-is particularly impaired in schizophrenia and could profit from further work with refined measurement tools. Thus, nominations for cognitive tasks that provide discrete measures of control of attention were sought and were then evaluated at the third CNTRICS meeting for their promise for future use in treatment development. This article describes the 5 nominated measures and their strengths and weaknesses for cognitive neuroscience work relevant to treatment development. Two paradigms, Guided Search and the Distractor Condition Sustained Attention Task, were viewed as having the greatest immediate promise for development into tools for treatment research in schizophrenia and are described in more detail by their nominators.

Fig. 1.

Typical Stimuli (a) and Idealized Results (b) From a Guided Search Task. Subjects look for a red square with a gap at the top among red and blue distractors. Set size is manipulated by varying the number of quadrants in which a cluster of items is presented, thus controlling stimulus density. RTs increase linearly as the set size increases. If a subject can limit search to the items of the relevant color, the slope of this function should be half as great when half of the items are drawn in this color than when all of them are drawn in this color.

Fig. 2.

Illustration of the Main Events (a), Response Categories and Outcome (b) of the SAT as Used in Rats and Illustration of Performance Data From SAT and dSAT Sessions (c–h; base task performance: black lines, squares; distractor condition: orange lines, triangles; data from Wistar rats; the presence of the distractor in blocks 2 and 3 is indicated by the oranges block on the abscissa). The performance in signal and nonsignal trials is collapsed into one measure of performance, the SAT/dSAT scores (h). SAT/dSAT scores are calculated for each signal duration (eg, 500, 50, 25 ms; SAT/dSAT_500,50,25) on the basis of the relative number of hits (h) and false alarms (f), in accordance with this formula: (SAT/dSAT = [(h − f)/2(h + f) − (h + f)²]) and then averaged over all signal durations, yielding a single overall score (h). The formula is a variation of the nonparametric calculation of signal sensitivity. Signal intensity is based on the probabilities for hits and false alarms. In contrast, the calculation of SAT/dSAT scores is based on the relative number of hits and false alarms, thereby removing the confounding effects of omissions from this performance measure. SAT/dSAT scores range from −1 to +1. Values of 0 indicate randomized lever section, +1 indicates perfect response accuracy in signal and nonsignal trials, and −1 indicates complete inaccuracy. The scores shown in (h) are averaged over all signal durations and depicted by block to visualize the contrast between SAT and dSAT scores.

Fig. 3.

SAT/dSAT Performance of Healthy Human Volunteers. Except for different signal durations and longer trial blocks, this figure allows direct comparisons with the data from rats illustrated in figure 2 (data taken from E. Demeter, M. Sarter, C. Lustig (personal communication); see legend of figure 2 for more details).