Individual differences and interrelationships among a select set of cognitive skills

An experiment was conducted to investigate individual differences and interrelationships in performance on three short-term memory processing and visual processing tasks. Parameters of models for these tasks were correlated. High correlations (.97 and .83) were obtained for some intertask parameters. indicating that elemental component processes for different tasks can be identified that are similar or highly related. Psychometric measures (SATM and SATV) were also correlated with the information processing model parameters. High multiple correlations of SATV and SATM were obtained using model parameters as predictors. when the data were analyzed separately for female and male subjects. The results are suggestive of sex differences in the interrelationships of the cognitive processes under investigation.     

Accuracy and speed strategies in scanning active memory

The effect of speed and accuracy payoff on performance in a short-term memory scanning task was investigated under two conditions of familiarity of material and two conditions of payoff. Memory sets and probes were either drawn from a small well learned pool of words (thefamiliar set) or were sampled without replacement from a very large pool of words (theinfinite set). Under both payoffs the infinite memory sets were searched at a faster rate than the familiar sets. The speed payoff reduced the constant component of latencies and, contrary to previous findings, increased the rate of memory search for both sets. Errors increased from about 1% with accuracy payoff to 19% with speed payoff. Under speed payoff most of the errors were false positives for the familiar set and false negatives for the infinite set. Several models of the task were considered, but none proved entirely satisfactory.     

Influence of correlated visual cues on auditory signal detection

Two experiments investigated the effects on auditory signal detection of introducing visual cues that were partially correlated with the signal events. The results were analyzed in terms of a detection model that assumes that such cue-signal correlations will not affect sensitivity, but will instead cause the subject to develop separate response biases for each cue. The model specifies a functional relationship between the asymptotic values of these cuecontingent biases. The overall results of the experiments supported the detection assumptions of the model and the general bias learning assumption, but indicated a more complex learning process than that specified by the model.     

Moderating influences of hypnotic susceptibility on signal-detection task performance

This study investigated the differential influence of hypnotic susceptibility level on signal detection task (SDT) performance in waking and hypnotic conditions. As assessed by the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS: A) and the Stanford Hypnotic Susceptibility Scale, Form C (SHSS: C), 20 high (9–12), 20 medium (4–8), and 20 low (0–3) hypnotizables participated. In counterbalanced conditions of waking and hypnosis, Ss (Subjects) were given 36 signal detection trials, consisting of 12 strong signals, 12 weak signals, and 12 “no” signals. No differences were observed in the waking condition between low, medium, and high hypnotizables on strong and weak signal trials. In hypnosis, high hypnotizables exhibited significantly superior performance on the strong signal trials in comparison with low hypotizables, and performed significantly better on the weak signal trials than did the low and medium hypnotizables. Low and medium hypnotizables performed similarly in waking and hypnotic conditions, while high hypnotizables showed significant enhancements in performance for strong and weak signal trials during hypnosis. This research was supported, in part, by a grant from Fort Hays State University.     

A generalization of stimulus sampling theory

A modification of stimulus sampling theory is presented. The restriction that each stimulus element is conditioned to one and only one response is replaced with the notion of a scale of conditioning for each element. This variation provides a context in which such variables as reward magnitude and motivation can be viewed as determiners of behavior. Some experimental results on multiple response problems also have a natural interpretation in terms of these ideas.     

Signal recognition as influenced by presentation schedules

Performance in a recognition task involving two amplitudes of the same tone was investigaled over a wide range of presentation schedules. The task was arranged so that there was no trial-to-trial feedback or other information regarding the relative frequencies of the two tones. The hit and false alarm rates (the proportion of “loud” responses to loud and soft stimuli, respectively) on any given trial were strongly influenced by the stimulus and response on the preceding trial. In general, Ss tended to repeat the last response and were more accurate after a stimulus alternation than after a stimulus repetition. In addition, hit and false alarm rates were inversely related to the presentation probability of the loud tone, in contrast to the direct relation typically found in signal detection experiments and in recognition experiments with trial-to-trial feedback. A mathematical model incorporating three processes (memory, comparison, and decision) was shown to give a good account of these data.     

Children reorient using the left/right sense of coloured landmarks at 18-24 months

In previous studies, children disoriented in small enclosures used room shape, but not wall colours, to find hidden objects. Their reorientation was said to depend solely on a "geometric module" informationally encapsulated with respect to colour. We argue that previous studies did not fully evaluate children's use of colour owing to a bias in the enclosures' design. In this study, disoriented 18-24 month olds searched for toys in small square enclosures with two blue and two white walls. Children successfully reoriented using wall colour. This shows that they can make location judgments based on the left/right sense of the colours of adjoining landmarks. Performance was no different when symmetric colourful shapes were added to walls, but improved with asymmetric shapes which could be used without left/right judgments. The relatively poor use of colour in previous studies may be explained partly by a bias in their design, and partly by children's limited ability to discriminate the left/right sense of nongeometric features.     

Developmental trajectories for spatial frames of reference in Williams syndrome

Williams syndrome (WS) is a genetic disorder associated with severe visuocognitive impairment. Individuals with WS also report difficulties with everyday wayfinding. To study the development of body-, environment-, and object-based spatial frames of reference in WS, we tested 45 children and adults with WS on a search task in which the participant and a spatial array are moved with respect to each other. Although individuals with WS showed a marked delay, like young controls they demonstrated independent, additive use of body- and environment-based frames of reference. Crucially, object-based (intrinsic) representations based on local landmarks within the array were only marginally used even by adults with WS, whereas in typical development these emerge at 5 years. Deficits in landmark use are consistent with wayfinding difficulties in WS, and may also contribute to problems with basic localization, since in typical development landmark-based representations supplement those based on the body and on self-motion. Difficulties with inhibition or mental rotation may be further components in the impaired ability to use the correct reference frame in WS.