Haptic perception of linear extent.

The perception of linear extent in haptic touch appears to be anisotropic, in that haptically perceived extents can depend on the spatial orientation and location of the object and, thus, on the direction of exploratory motion. Experiments 1 and 2 quantified how the haptic perception of linear extent depended on the type of motion (radial or tangential to the body) when subjects explored different stimulus objects (raised lines or solid blocks) varying in length and in relative spatial location. Relatively narrow, shallow, raised lines were judged to be longer, by magnitude estimation, than solid blocks. Consistent with earlier reports, stimuli explored with radial arm motions were judged to be longer than identical stimuli explored with tangential motions; this difference did not depend consistently on the lateral position of the stimulus object, the direction of movement (toward or away from the body), or the distance of the hand from the body but did depend slightly on the angular position of the shoulder. Experiment 3 showed that the radial-tangential effect could be explained by temporal differences in exploratory movements, implying that the apparent anisotropy is not intrinsic to the structure of haptic space.     

Novelty and frequency as determinants of newborn preference

The debate over whether infants prefer a familiar stimulus over a novel stimulus has persisted for over 30 years, and there is evidence which supports both sides of the question. However, the research which supports the preference for the familiar uses different measures than that which supports the preference for novelty. In the first experiment, the preference for the familiar was tested by making one stimulus more familiar than the others presented. A target of a ‘familiar’ face was presented eight times more frequently than the other faces. During the experiment, the infants could choose at which face they looked and for how long. It was found that the infants significantly preferred the familiar face over any one of the novel faces, especially when the familiar face was presented first. Substituting auditory for visual stimuli, the second experiment was a replication of the first experiment. Consonant–vowel syllables were used instead of faces. Overall, 17 stimuli were used: one repeating ‘familiar’ sound, and 16 novel sounds. It was found that the infants significantly preferred the familiar sound over any of the novel sounds. As found in Experiment 1, the infants also had a greater preference for the familiar sound when it was presented first.     

Faces as forms in the world of the newborn

A number of recent studies have indicated that newborns can learn to recognize mother's face within a few hours of birth. Two of the present authors suggested that a simple auto-associative net might explain that rapid learning. This paper reports three experiments in which the newborn's ability to recognize a learned face over three transformations was tested. The transformations were: (1) a photonegative transformation, (2) a size change and (3) rotation in the third dimension of visual space. Existing auto-associative nets cannot maintain identification across these transformations. The newborns succeeded with all three. An alternative proposal based on the idea that there is a built-in specification of the true shape of a face in the frontal parallel plane is outlined. These data present a challenge not only to associationist theories but also to their main rival, differentiation theory.     

Effects of performance expectancies created by peer comparison as related to social reinforcement,task difficulty,and age of child

Children in kindergarten-first grades and fourth-sixth grades (6 and 10 years of age, respectively) participated in one of two experiments and performed either a simple motor task or (for older children only) a two-choice simultaneous discrimination task at two difficulty levels. Children received either positive, negative, or no peer comparison statements (describing how other children their age had allegedly performed) and either praise, silence (in Experiment 2 only), or criticism on a fixed-interval 20-second schedule throughout the task. Young children were more responsive to adult evaluation of their performance than to peer comparison. Expectancies created by peer comparisons affected older children's motor performance most if they received reinforcement contrary to the expectancy. In situations requiring greater cognitive ability, older children, particularly boys, responded to the performance expectancies created by positive peer comparison. Older boys, compared with older girls, seemed to be more sensitive to peer comparison and social reinforcement.     

Fourier analysis of polar coordinate data in visual physiology and psychophysics

Techniques are presented for analyzing data collected as a function of: a circular independent variable (e.g., angle, direction, or orientation) or an independent variable which is cyclical (e.g., months of the year). The procedures are presented in a tutorial manner, emphasizing their relationship to more traditional statistics in experimental psychology.     

Synonym comprehension and the generality of categorization models

Memory & Cognition - When subjects classify a two-word display as representing the “same” category or two “different” categories, semantic similarity between the words...     

Support systems of elders in rural communities

The social network concept can be used to guide the extension of the mental health clinician's role to the practice of prevention on the local level. A model of such work is described which builds on clinical skills in collaborative consultation with formal and informal social support networks in a community. The model is illustrated and expanded through a case example of a project in a rural New England town to address issues of stress and support for frail elders. Focusing on the social network of such elders, consultations were developed to address the needs of middle generation caregivers, natural helpers, organized community associations, general community attitudes toward aging, and the ability of the community to secure and use outside resources. Issues of community entry through natural sponsorship are reviewed and the overall process of community empowerment is emphasized as a guiding principle in work with social networks.     

Metamorphosis of the Mushroom Bodies; Large-Scale Rearrangements of the Neural Substrates for Associative Learning and Memory in Drosophila

Paired brain centers known as mushroom bodies are key features of the circuitry for insect associative learning, especially when evoked by olfactory cues. Mushroom bodies have an embryonic origin, and unlike most other brain structures they exhibit developmental continuity, being prominent components of both the larval and the adult CNS. Here, we use cell-type-specific markers, provided by the P{GAL4} enhancer trap system, to follow specific subsets of mushroom body intrinsic and extrinsic neurons from the larval to the adult stage. We find marked structural differences between the larval and adult mushroom bodies, arising as the consequence of large-scale reorganization during metamorphosis. Extensive, though incomplete, degradation of the larval structure is followed by establishment of adult specific α and β lobes. Kenyon cells of embryonic origin, by contrast, were found to project selectively to the adult γ lobe. We propose that the γ lobe stores information of relevance to both developmental stages, whereas the α and β lobes have uniquely adult roles.