Bias toward regular form in mental shape spaces

The distribution of figural "goodness" in 2 mental shape spaces, the space of triangles and the space of quadrilaterals, was examined. In Experiment 1, participants were asked to rate the typicality of visually presented triangles and quadrilaterals (perceptual task). In Experiment 2, participants were asked to draw triangles and quadrilaterals by hand (production task). The rated typicality of a particular shape and the probability that that shape was generated by participants were each plotted as a function of shape parameters, yielding estimates of the subjective distribution of shape goodness in shape space. Compared with neutral distributions of random shapes in the same shape spaces, these distributions showed a marked bias toward regular forms (equilateral triangles and squares). Such psychologically modal shapes apparently represent ideal forms that maximize the perceptual preference for regularity and symmetry.     

How surprising is a simple pattern? Quantifying "Eureka!"

Simple patterns are compelling. When all the observed facts fit into a simple theory or "story," we are intuitively convinced that the pattern must be real rather than random. But how surprising is a simple pattern, really? That is, given a pattern of featural data, such as the properties of a set of objects, how unlikely would the pattern be if they were actually generated at random? In conventional statistics dealing with patterns of numbers, this type of question would be answered by reference to a null distribution such as the t distribution. This paper gives the analogous answer in the realm of concept learning, that is, the formation of generalizations from patterns of featural data. Using a formal but psychologically valid definition of complexity, I derive and exhibit the distribution of subjective complexity under the hypothesis of no pattern. This leads directly to a number of applications, including a statistical test indicating whether an observed pattern is sufficiently simple that it is not likely to have been an accident: literally, the "significance of simplicity."     

Parent-infant synchrony and the social-emotional development of triplets

To study the social-emotional development of triplets, 23 sets of triplets, 23 sets of twins, and 23 singleton infants (N=138) were followed from birth to 2 years. Maternal depression and social support were assessed in the postpartum period, mother-infant and father-infant interaction and the home environment were observed at 3 months, a separation-reunion episode and a maternal interview were conducted at 12 months, and infant behavior problems were evaluated at 24 months. Lower parent-infant synchrony was observed for triplets. Triplets showed less distress during maternal separation and less approach at reunion. Mothers reported lower adjustment and differentiation among siblings for triplets than for twins. Higher internalizing problems were reported for triplets, and the triplet with intrauterine growth retardation showed the poorest outcomes. Behavior problems were predicted by medical risk, maternal depression, parent-infant synchrony, infant approach, and mother adjustment. Discussion focuses on developmental risk when the exclusivity of the parent-infant relationship is compromised.     

Valence focus and the perception of facial affect

Individuals differ in the extent to which they emphasize feelings of pleasure or displeasure in their verbal reports of emotional experience, an individual difference termed valence focus (VF). This multimethod study indicates that VF is linked to heightened efficiency in perceptual processing of affective stimuli. Individuals higher in VF (i.e., who emphasized feelings of pleasure/displeasure in reports of emotional experiences) were more sensitive to changes in negative facial expressions than individuals lower in VF. The effect was not accounted for by current affective state or other personality characteristics. Implications for the validity of self-reported experienced emotion are discussed.     

Detection of change in shape: an advantage for concavities

Shape representation was studied using a change detection task. Observers viewed two individual shapes in succession, either identical or one a slightly altered version of the other, and reported whether they detected a change. We found a dramatic advantage for concave compared to convex changes of equal magnitude. Observers were more accurate when a concavity along the contour was introduced, or removed, compared to a convexity. This result sheds light on the underlying representation of visual shape, and in particular the central role played by part-boundaries. Moreover, this finding shows how change detection methodology can serve as a useful tool in studying the specific form of visual representations.