A comparison of cognitive function in community-dwelling and institutionalized old people of normal intelligence

Two carefully matched groups of normal old people living in institutions or in the community were administered a neuropsychological cognitive test battery. In general, the institutionalized group performed worse than the community group. Discriminant function analysis identified a subgroup of high-functioning institutionalized subjects whose performance more closely resembled that of the community group than the remainder of the institutionalized group. Differences between the various groups were not due to differences in IQ, age, health, or other controlled variables. The critical tests that differentiated the groups were sensitive to impaired function in frontal and medial-temporal lobe brain regions. The results suggest a complex interaction involving effects of age and environmental factors on brain function and cognition.     

A historical perspective on recent studies of social learning about foods by Norway rats

Early naturalists explained field observations of social influences on animal learning in terms of spoken language, deliberate tuition of one animal by another, or intentional imitation. During the first half of the present century, experimental psychologists analyzed instances of social learning by animals in laboratory tasks as special cases of operant or classical conditioning. Neither of these traditional approaches provided much insight into the complex processes that often support animal social learning. By combining ethological focus on social learning as it occurs in natural habitat with analytical techniques developed in the psychological laboratory, contemporary researchers have made considerable progress in describing the many ways in which social interactions influence behavioural development in animals. The author's investigations of social influences on food selection by Norway rats provide one example of such an ethopsychological approach to the study of animal social learning.     

Peer-group association and adolescent tobacco use

Mosbach & Leventhal (1988) examined the relation of cigarette smoking to peer-group identification in rural Wisconsin adolescents. They found that among dirts (problem-prone youth), regulars (average youth), hot-shots (good social or academic performers), and jocks (athletes), youth most likely to smoke were dirts and hot-shots. We performed a replication with a Southern California cohort and also for use of smokeless tobacco. We hypothesized that jocks would be the main users of smokeless tobacco. We identified the same groups and an additional one, skaters (skateboarders or surfers). As Mosbach & Leventhal found, cigarettes were used most by dirts. Contrary to their results, but consistent with other research, we found that hot-shots were least likely to smoke. Contrary to our prediction, we found that skaters and dirts were more likely to use smokeless tobacco than were jocks. Our data show that both tobacco forms are used by problem-prone youth.     

Pursuit gain and saccadic intrusions in first-degree relatives of probands with schizophrenia

Oculomotor functioning of 26 probands with schizophrenia, 12 spectrum and 46 nonspectrum first-degree relatives, and 38 nonpsychiatric control subjects was evaluated. Spectrum relatives had more anticipatory saccades (ASs) and lower pursuit gain than nonspectrum relatives, who had more ASs and lower pursuit gain than control subjects. Probands also had lower pursuit gain than nonspectrum relatives and control subjects but did not differ from other groups on AS frequency. Control subjects had more globally accurate pursuit tracking (root mean square [RMS] error deviation) than both relative groups, whereas probands had the poorest RMS scores. Square wave jerk frequency did not differentiate the groups. Attention enhancement affected the frequency of ASs but did not affect either the other intrusive saccadic event or RMS scores. These results offer evidence that eye-movement dysfunction may serve as a biological marker for schizophrenia.     

The Influence of Source Physical Attractiveness on Advertising Effectiveness: A Functional Perspective1

High and low self-monitors heard either a physically attractive or unattractive source promote a new product with either strong or weak arguments. High self-monitors were persuaded by the physically attractive source only when she presented strong arguments. In contrast, low self-monitoring individuals were persuaded by the physically attractive source regardless of argument strength. Neither high nor low self-monitors were persuaded by the physically unattractive source, regardless of the quality of the arguments she offered. Cognitive response and recall data suggest that high self-monitors may have been systematically processing the physically attractive source's message and low self-monitors may have been more heuristically processing her message. Results are discussed in terms of their implications for advertising strategies.     

Second-Guessing the Jury: Stereotypic and Hindsight Biases in Perceptions of Court Cases1

This research examined the effects of stereotypic beliefs and hindsight biases on perceptions of court cases. Subjects read evidentiary material pertaining to a criminal trial in which the defendant either was a stereotyped offender or was not. Additionally, some subjects were given outcome information about the verdict attained in the trial; half of these subjects were told that the defendant had been found guilty, and the other half were told that he had been found not guilty. The remainder were not given any outcome information. Subjects were than asked to predict the likely outcome of a trial based on the presented evidence. Typical hindsight bias effects were expected and obtained for nonstereotyped offenders; subjects considering these cases viewed the evidence as less incriminating when they were told the defendant had been found not guilty, and they found it to be more incriminating when they were told the defendant had been found guilty, when compared to the no-outcome-information group. However, no hindsight biases were evident in judgments of cases involving stereotyped defendants, who were seen as relatively more likely to be guilty regardless of the nature of outcome information presented. Particularly striking was the lack of impact of the “not guilty” outcome information on perceptions of the guilt of stereotyped defendants. These findings suggest that strong expectations held in foresight may not be amenable to modification in hindsight.     

Temporal regularity of tapping by the left and right hands in timed and untimed finger tapping

The temporal characteristics of repetitive finger tapping by the left and right hands were examined in two experiments. In the first experiment, interresponse intervals (IRIs) were recorded while right-handed male subjects tapped in synchrony with an auditory timing pulse (the synchronization phase) and then attempted to maintain the same tapping rate without the timing pulses (the continuation phase). The left and right hands performed separately, at four different rates (interpulse intervals of 250, 500, 750, and 1500 ms). There was no asymmetry of the asynchronies of the timing pulses and the associated responses in the synchronization phase or of the IRIs in either phase, but there was an asymmetry of chronization phase or of the IRIs in either phase, but there was an asymmetry in the temporal dispersion of the responses in both phases. in the second experiment, right-handed males tapped separately with each hand at three different speeds: as quickly as possible, at a fast but steady rate, and at a slow rhythmical rate. The speed asymmetry present when tapping as quickly as possible (with the preferred hand tapping more quickly ) was reduced when tapping at the fast steady rate and was absent when tapping at the slow rhythmical rate. The temporal dispersion of the IRIs produced by the nonpreferred hand was greater than the temporal dispersion of those produced by the preferred hand in all speed conditions. These results show smaller temporal dispersion of tapping by the preferred hand in right-handed males under different conditions, including submaximal speeds at which both hands respond at the same rate. This suggests that the motor system controlling the preferred hand in right-handers had more precise timing of response output than that controlling the nonpreferred hand.     

The effect of motor preparation on changes in h reflex amplitude during the response latency of a warned reaction time task

Monosynaptic Hoffman reflexes (H reflexes) were recorded from the soleus muscle during the response latency of a warned reaction time (RT) task that required plantarflexion of the foot. The task was done under four conditions of predictability of the response signal (RS), created by the factorial combination of foreperiod duration (1 and 4 s) and variability (fixed and variable). RT varied systematically with RS predictability and was facilitated in conditions that favored prediction of the RS. The response latency was divided into two successive phases by the onset of reflex augmentation: a premotor phase of constant reflex amplitude and a succeeding motor phase marked by progressively increasing reflex amplitude. Reflex augmentation during the motor phase was coupled more closely to the imminent movement than to the preceding signal to respond. The duration of the premotor phase was unaffected by RS predictability, but the duration of the motor phase (like RT) was shorter when the RS was more predictable. The maximum H reflex amplitude reached during the motor phase was greater when the RS was more predictable. The tonic level of H reflex amplitude during the premotor phase was greater in conditions that made prediction of the RS difficult. A second experiment showed that this difference was present throughout the foreperiod. These results suggest that conditions that favor prediction of the RS enhance motor preparation. changes in motor preparation (which affect RT) affect the processes underlying reflex amplitudes in the premotor phase and throughout the preceding foreperiod, in conditions that make prediction of the RS difficult, appear to reflect heightened general arousal.     

Preload and isometric force variability

Two experiments are reported, which examined the relative contributions of preload (resting force level), change of force, and the time taken to achieve the force in determining isometric force variability. The findings showed that change of force is the strongest determiner of peak force variability but that preload and time to peak force have smaller though systematic effects. A formula that predicts peak force variability is proposed, with preload as an additive effect to the ratio between the change of force level and the square root of time to peak force. These findings confirm that these three impulse variables are significant in predicting force variability and that the impact of rate of force on peak force variability is nonlinear.