Gaze following: why (not) learn it?

We propose a computational model of the emergence of gaze following skills in infant-caregiver interactions. The model is based on the idea that infants learn that monitoring their caregiver's direction of gaze allows them to predict the locations of interesting objects or events in their environment (Moore & Corkum, 1994). Elaborating on this theory, we demonstrate that a specific Basic Set of structures and mechanisms is sufficient for gaze following to emerge. This Basic Set includes the infant's perceptual skills and preferences, habituation and reward-driven learning, and a structured social environment featuring a caregiver who tends to look at things the infant will find interesting. We review evidence that all elements of the Basic Set are established well before the relevant gaze following skills emerge. We evaluate the model in a series of simulations and show that it can account for typical development. We also demonstrate that plausible alterations of model parameters, motivated by findings on two different developmental disorders - autism and Williams syndrome - produce delays or deficits in the emergence of gaze following. The model makes a number of testable predictions. In addition, it opens a new perspective for theorizing about cross-species differences in gaze following.     

Audiospatial and visuospatial working memory in 6-13 year old school children

The neural processes subserving working memory, and brain structures underlying this system, continue to develop during childhood. We investigated the effects of age and gender on audiospatial and visuospatial working memory in a nonclinical sample of school-aged children using n-back tasks. The results showed that auditory and visual working memory performance improves with age, suggesting functional maturation of underlying cognitive processes and brain areas. The gender differences found in the performance of working memory tasks suggest a larger degree of immaturity in boys than girls at the age period of 6–10 yr. The differences observed between the mastering of auditory and visual working memory tasks may indicate that visual working memory reaches functional maturity earlier than the corresponding auditory system.     

Hemispheric asymmetries for global and local processing as a function of stimulus exposure duration

The experiments assess the relationship between stimulus exposure duration and hemispheric asymmetries for global and local processing. Six durations (27, 40, 53, 67, 80, and 147 ms) were tested in a selective attention task in which hierarchical letterforms were presented unilaterally to the left or right visual field. The results indicated that left hemisphere-local asymmetries were demonstrated more often than right hemisphere-global asymmetries and that asymmetries were most commonly found in the middle range of durations tested. The pattern of results emphasizes the importance of further study into those conditions under which the predicted asymmetries can be reliably demonstrated in healthy individuals.     

Toward a differential testing approach: Testing-the-limits employing the Raven matrices

Various testing-the-limits procedures were employed in administering the Raven Coloured Progressive Matrices Test to 203 second grade and 230 fourth grade children. Tests of impulsivity, neuroticism, extroversion, intelligence and school achievement were also given. The main results showed that testing-the-limits procedures which involved verbalization and feedback were efficacious in maximizing performance on the Raven. The puzzle form of the test generally led to higher scores than the picture version for the second but not fourth graders. Differential analyses were carried out to establish how construct, concurrent and predictive validity of the Raven were affected by the salient testing-the-limits procedures involved. Analysis was also done with the personality variables and revealed how their effect interacted with various test administration procedures. The results were discussed in theoretical and practical terms.     

Consistency in attitude and behavior of women with a liberated attitude toward the rights and roles of women

The study was designed to determine the extent of consistency of attitude and behavior of women with liberated attitudes toward their rights and roles, and to identify determinants of inconsistency between attitude and behavior. The Attitude Towards Women Scale, Rotter's locus of control scale, the Ego-Strength Scale, the Self-Esteem Scale, the Liberated Behavior Questionnaire, and the Attitude of Family and Friends Questionnaire were administered to 242 women. Women with more liberated attitudes tended to act more liberated. Also, women with liberated attitudes tended to act more liberated if their close friends were liberated and if they themselves were more aware of leaders in the women's liberation movement. The personality measures did not relate to the tendency to act liberated.     

Transfer of persistence to the acquisition of a new behaviour

Two experiments tested whether the degree of effort required for the reinforcement of one behaviour would affect the acquisition of a second behaviour. In the first experiment, rats were placed in a conditioning chamber and: (a) were required to press a lever for food pellets on a fixed ratio schedule, (b) received free presentation of the pellets, or (c) did not receive pellets. Next, all rats were rewarded for a new behaviour, round trips across the length of a runway. As predicted, the fixed-ratio group had the greatest shuttle rate. In the second experiment, two groups were required to press a lever, and the number of presses per pellet was varied. For two other groups not required to press the lever, the amount of food presented per approach to the feeder was varied. The greater required number of lever presses and the lesser number of pellets per approach to the feeder produced the higher subsequent shuttle rates. Two alternative explanations were compared: the degree of accustomed effort per reinforcer becomes a learned component of behaviour, or high effort increases the habituation of frustration-produced disruptive responses.