Effects of list length and first-trial reward upon concurrent discrimination performance

Rhesus monkeys were given 2304 two-trial object discrimination problems that were presented as members of lists consisting of two, four, or eight problems. The problems within each list were presented concurrently, Trial 1 for all problems in the list being presented before initiation of Trial 2 for any problem. Each problem involved exposure of a single object on Trial 1, which was either rewarded or not rewarded, followed by presentation of the Trial 1 object along with a second object on Trial 2. Performance varied inversely with list length, and this effect became more prominent as a function of training. Performance after Trial 1 nonreward was substantially better than that after Trial 1 reward, and this effect became enhanced both with continued training and with increased list length. The findings were discussed in terms of Bessemer's short-term memory analysis of learning set.     

Deficits in set-shifting ability in nonclinical compulsive checkers

Recent studies suggest deficits in set-shifting ability in patients with obsessive-compulsive disorder (OCD) as measured by tasks such as the Wisconsin Card Sorting Test (WCST; Berg, 1948). The present study examined the extent to which these deficits were demonstrated by nonclinical subjects selected on the basis of their checking scores on the Maudsley Obsessional-Compulsive Inventory. A multivariate analysis revealed that frequent checkers performed significantly worse on the WCST than noncheckers, making more total errors and more perseverative errors and requiring more time to complete the test. A follow-up analysis on a subset of the original sample found similar performance deficits in checkers. While the poorer performance of checkers could be statistically accounted for by anxiety during the first administration of the WCST, anxiety could not explain the relationship between checking status and WCST performance at follow-up. Therefore, there does appear to be some relationship between checking status and WCST performance beyond what can be explained by affective variables.     

Cognitive differentiation as a function of information type and its relation to career choice

Although providing occupational information is a common vocational counseling practice, recent research has raised questions about the utility of such information. Cognitive differentiation (the ability to differentiate among job titles on 12 constructs) has been shown to be positively related to an “appropriate” career choice. Differentiation, however, appears to decrease as a function of traditional types of occupational information (e.g., Occupational Outlook Handbook, U.S. Department of Labor, Washington, D.C., 1980). The present study investigated the hypothesis that information related to Holland personality characteristics of persons in various occupations would increase subjects' ability to differentiate among those job titles. One hundred fifty undeclared-major freshman undergraduate students were randomly assigned to one of three condition groups: objective information, personality information, no information. All subjects were administered the Career Decision Scale and Cognitive Differentiation Grid. Results indicated that subjects receiving personality information exhibited a significantly greater degree of differentiation among careers than subjects receiving objective information. These results confirm the major hypothesis of the study and suggest that the provision of personality information may be more useful in promoting career choice than the types of information traditionally provided.     

Dissociation between conditioned emotional response and extended avoidance performance

The present experiments examined the dissociation between the strength of a shuttlebox avoidance response (AR) and one index of fear of the avoidance CS. Avoidance response strength was indexed by resistance to extinction of the AR and by changes in response latency, and fear of the CS was indexed by the conditioned emotional response (CER) technique. Experiments 1, 2A, and 3A all found that rats trained to a criterion of 27 consecutive avoidance responses (CARs) showed response strength comparable or superior to rats trained to a criterion of 9 CARs. Experiments 2B and 3A demonstrated that rats trained to 27 CARs showed less suppression of bar pressing during the avoidance CS (less CER) than rats trained to 9 CARs. Experiment 3A also found that, when extinguished in the shuttlebox to a moderate criterion (5 consecutive trials without a response) before CER testing, rats trained to 9 CARs showed some, although not complete, loss of CER, whereas rats trained to 27 CARs showed no loss of CER. In Experiment 3B rats that took 1 vs 2 days to reach a criterion of 27 CARs were compared for their AR strength and for their CER. Although rats taking 2 days to reach criterion showed somewhat greater resistance to extinction of the AR than rats reaching criterion in 1 day, this variable had no apparent effect on the CER. Implications of the present results for current theories of avoidance learning are discussed.     

Latency and accuracy characteristics of saccades and corrective saccades in children and adults

Accuracy and latency characteristics of the first saccade to a target together with the frequency and latency of corrective saccades were studied in children (mean age = 8.5) and adults. The independent variables manipulated were fixation-light offset to target-light onset warning interval (0 and 300 msec) and the presence and location of nontarget stimuli. Although saccade accuracy was significantly affected by nontarget lights, children could respond as accurately as adults and, in replication of previous findings, as quickly when a 300 msec warning interval was given. No speed-accuracy trade off was found for either group as a function of the warning signal condition. Children were as likely to make corrective saccades as adults, but did so with a significantly longer latency. Corrective saccade latencies were greater when a change in direction was required but this effect did not interact with age.     

The role of lateral masking and orthographic structure in letter and word recognition.

The present experiments evaluated the contribution of orthographic structure and lateral masking in the perception of letter, word, and nonword test displays. Performance was tested in a backward recognition masking experiment in which a masking stimulus followed the test display after a variable blank interstimulus interval. In agreement with previous findings across different experiments, words were recognized better than single letterd at short interstimulus intervals, but the opposite was the case at long intervals. Performance on the nonwords resembled performance on letters at short masking intervals and performance on words at long masking intervals. The quantitative results were described by a processing model that incorporates the effects of lateral masking and orthographic structure in the dynamic processing of letter strings. Lateral masking tends to lower the potential perceptibility of letters whereas orthographic structure can reduce the uncertainty of the candidate letters in the letter sequence. The present model predicts that the quantitative contribution of each of these processes to performance is critically dependent upon the processing time available before the onset of the masking stimulus.     

Rapid cerebral hemodynamic modulation during set shifting: Evidence of time-locked associations with cognitive control in females

Set shifting provokes specific alterations of cerebral hemodynamics in basal cerebral arteries. However, no gender differences have been reported. In the following functional transcranial Doppler study, we introduced cerebral hemodynamic modulation to the aspects of set shifting during Wisconsin Card Sorting Test (WCST). Twenty-one subjects underwent the WCST during insonation of the middle cerebral arteries. We examined gender effects on task performance and cerebral hemodynamic modulation. Further, we investigated the linkage between performance and cerebral hemodynamic modulation. In females, maximum positive modulation was restricted to the behaviorally relevant time point of set shifting, and there were time-locked associations between mental slowing during set shifting and rapid cerebral hemodynamic modulation exclusively in females. This study provides evidence of gender-related cerebral hemodynamic modulation during set shifting, and we detected time-locked brain–behavior relationship during cognitive control in females.     

Sequential learning models for the Wisconsin card sort task: Assessing processes in substance dependent individuals

The Wisconsin card sort task (WCST) is a commonly used neuropsychological test of executive or frontal lobe functioning. Traditional behavioral measures from the task (e.g., perseverative errors) distinguish healthy controls from clinical populations, but such measures can be difficult to interpret. In an attempt to supplement traditional measures, we developed and tested a family of sequential learning models that allowed for estimation of processes at the individual subject level in the WCST. Testing the model with substance dependent individuals and healthy controls, the model parameters significantly predicted group membership, even when controlling for traditional behavioral measures from the task. Substance dependence was associated with (a) slower attention shifting following punished trials and (b) reduced decision consistency. Results suggest that model parameters may offer both incremental content validity and incremental predictive validity.     

Developmental differences in empathy with a television protagonist's fear

An experiment was conducted to determine whether children at different ages (3-5 vs 9-11) differ in their tendency to share the emotion of a television character. Subjects were shown a videotape of either a frightening stimulus alone or a character's fear in response to a threatening stimulus that was suggested rather than shown directly. Contrasting predictions were made based on a cognitive-developmental view of the process of empathy vs an automatic conception. Both self-reported emotional reactions and physiological responses were consistent with the cognitive-developmental approach: The younger children were less emotionally aroused by the character's fear than by the fear-provoking stimulus, while the older children responded emotionally to both versions of the videotape. The younger children's lack of empathy was not due to a failure to recognize the nature of the character's emotion. There was some evidence that the older children exhibited a greater tendency to role take than did the younger children.