Life history and social learning: megapode chicks fail to acquire feeding preferences from conspecifics

Australian brush-turkeys, Alectura lathami, are birds with an unusual life history: The young receive no parental care and first encounter conspecifics at an unpredictable age. Brush-turkey chicks that were 3-4 days old were presented with a robot model that appeared to feed from a distinctively colored dish. In control training trials, chicks saw a robot standing next to a different dish and scanning from side to side. Chicks expressed a strong tendency to feed from dishes of the type indicated by the pecking robot, but this effect proved ephemeral. Brush-turkeys hence appear to show no social learning under conditions that inculcate stable preferences in other galliforms such as chickens, suggesting that life history plays an important role in the evolution of learning.     

Do behavioral disturbances in persons with Alzheimer's disease predict caregiver depression over time?

Random effects models were used to examine the association between behavioral disturbances in persons with Alzheimer's disease (N = 90) and caregiver depressive symptoms at 2-month intervals over an 18-month period. There was substantial variability in trajectories of change in caregiver depressive symptoms over time but no systematic increase in distress despite increased severity of dementia symptoms. Total behavioral disturbances were associated with higher levels of caregiver depressive symptoms: this effect was primarily attributable to aggressive behaviors. No consistent departure from linearity was evident in the relationship between behavior and depression over time.     

Georg von Békésy: visualization of hearing

Georg von Békésy received the Nobel Prize in 1961 for his research on the functioning of the auditory system. In psychoacoustics, Békésy both extended and perfected the lines of research begun by von Helmholtz in the 19th century. First in his native Hungary and later at Harvard, Békésy used novel and imaginative devices and methods to observe and model the functioning of the inner ear. He also explored the nature of sensory inhibition by which the nervous system sharpens sensory transitions.     

An analysis of response,direction, and place learning in an open field and T maze

Rats were trained to locate food in a response, direction, or place problem on an open field located at 2 positions. In Experiment 1, both the response and direction groups solved the problem. The place group failed to solve the task in approximately 300 trials. Experiment 2 demonstrated that rats need distinguishable start points to solve a place problem when neither a response nor a direction solution is available. Findings from Experiment 3 suggest that a combination of path traveled and distinct cues help to differentiate start points. Experiment 4 replicated the findings using a T maze. These results suggest "place" solutions are difficult for rats. The data are discussed with respect to conditional learning and modern spatial mapping theory.     

The S-S construct of expectancy versus the S-R construct of fear: which motivates the acquisition of avoidance behavior?

The authors provided a differential test between stimulus-stimulus (S-S) and stimulus-response (S-R) theory predictions in regard to the roles that the constructs of expectancy and of fear play in maintaining classically conditioned fear responding within the context of a human conditioned-avoidance paradigm. After the participants had developed sustained avoidance responding, their shock electrodes and avoidance response apparatus were removed to enhance the cognitive expectancy that the conditioned stimulus (CS) would not be followed by the unconditioned stimulus (UCS). This manipulation of expectancy was successful in 96% of the participants. The study was conducted over a 2-day period and involved 1 experimental group and 3 control groups. During the test trials, the authors used autonomic and self-report indices of fear to assess the presence or absence of fear to the CS. The data disconfirmed the prediction of the S-S theory that fear to the CS would be extinguished. The authors discuss the implications of this finding for S-S theories and for approaches in cognitive behavior therapy.     

Parental language and verbal responsiveness to children in crowded homes.

This article is a secondary data analysis of the University of Kansas Language Acquisition Project, which intensively studied, on a regular basis, parent and child language from age 6 months to 30 months. The association between residential density and parent-child speech was examined. Parents in crowded homes speak in less complex, sophisticated ways with their children compared with parents in uncrowded homes, and this association is mediated by parental responsiveness. Parents in more crowded homes are less verbally responsive to their children. This in turn accounts for their simpler, less sophisticated speech to their children. This mediational pathway is evident with statistical controls for socioeconomic status. This model may help explain prior findings showing a link between residential crowding and delayed cognitive development.     

Occupational prestige: Exploration of a theoretical basis

Drawing on the theory and research of psychophysics, a nonlinear model is hypothesized to explain the connection between education and income and occupational prestige. To achieve this, Weber's (R. L. Gregory, 1981, Mind in Science, Cambridge, Cambridge Univ. Press, pp. 501–503) and Stevens' (S. S. Stevens, 1970, Science170, 1043–1050) laws are brought together in an intrinsically nonlinear model. Guided by the earlier work of R. L. Hamblin (1971, Sociometry, 34, 423–452) and others, the work of O. D. Duncan (1961, in A. J. Reiss, Jr., O. D. Duncan, P. K. Hatt, & C. C. North (Eds.), Occupations and Social Status, New York, Free Press) is reanalyzed testing the possibility that work on the socioeconomic index can be understood as a prestige allocation process which follows psychophysical principles. That is, prestige is assigned to occupations, given specifiable levels of educational and income attainment, in a manner parallel to the way in which individuals respond to changes in the intensity of other stimuli. Using first the data developed by Duncan (1961) to test the model and the 1963 NORC data (R. W. Hodge, P. M. Siegel, & P. H. Rossi, 1964, American Journal of Sociology, 70, 286–302) to replicate it, a measurement model consistent with the theoretical model is evaluated. Comparing the results of the nonlinear model to that of the linear, it is concluded that a model is obtained yielding theoretical confirmation with no loss in predictive accuracy. The resultant nonlinear model yields alternative substantive implications concerning the relative influence of income and education on occupational prestige to those to be inferred from linear models. Perhaps most important, however, is the candidacy given by these results to psychophysics as the explanatory mechanism in the prestige allocation process.     

The effects of distraction,performance demand,stimulus explicitness and personality on objective and subjective measures of male sexual arousal

The interaction of several parameters known to influence sexual arousal was investigated in a 2 × 2 × 2 factorial design. Distraction, performance demand, and the sexual explicitness of the arousing film were manipulated, with 32 male subjects randomly assigned to the experimental groups. Sexual arousal was elicited by either an explicit or nonexplicit videotape; level of performance demand was determined by one of two sets of experimental instructions: distraction, a within-subject factor, was produced by tone presentations. Arousal was assessed by both penile tumescence and a continuous subjective measure: marked individual differences were found in the degree to which these measures covaried. The results indicated a strong effect of distraction on tumescence, though none on subjectively reported arousal. Conversely. degree of film explicitness had a marked effect on subjective arousal without influencing tumescence. The performance-demand main effect was nonsignificant; however, a significant distraction x demand interaction for maximum tumescence was evident. Additional analyses indicated the predictive value of certain personality measures.     

Children''s self-initiated approach to spiders

Seventeen school children were invited to stay in the presence of a harmless spider for 4 minutes under instructions which were designed mildly to encourage touching the spider but which left open a clear alternative of not touching. Subjects confronted the spider in dyads which differed in composition in terms of fear-level and sex of subjects. The main finding was that boys did not show any more approach when paired with girls, thus confirming previous negative findings in this regard. Other findings were that boys showed more approach than girls, level of fear interacted with sex of subject, and ‘fearless’ but not ‘fearful’ subjects showed more approach with repeated experience.