Contour deletion as a method for identifying the weights of features underlying object recognition

A prerequisite for comparative work on object recognition is a method for identifying the features actually extracted from the form. The method introduced here with pigeons is discrimination training between two simple line drawings, followed by a generalization test in which contour is deleted from the reinforced drawing. In Condition 1, the line drawings were a square (S+) versus a triangle (S-); for Condition 2, the line drawings were planar projections of a cube (S+) versus a truncated pyramid (S-). The generalization decrement between responses to S+ and responses to test stimuli provides a quantitative index of the weight assigned to each feature. Contour deletion at either vertices or midsegments produced a decrement in the rate of responding, showing that each contour was represented as a feature. The generalization decrement to forms containing vertices with midsegments deleted was larger than the generalization decrement to forms containing midsegments with vertices deleted. Therefore, it appears that midsegments are weighted more strongly as features than vertices. Contour deletion provides a direct method for identifying the visual features underlying object recognition and lays a foundation for the development of comparative theories of object recognition.     

ADOLESCENT DAUCHTER/MIDLIFE MOTHER DYAD A New Look at Separation and Self-Definition

The mother-daughter relationship is seen as complex, unique, and emotionally charged, with adolescence being the most difficult period for this dyad. Yet much of the literature has highlighted the struggle of adolescents, while underemphasizing that many of their mothers themselves are confronting their own developmental issues at this time. In this article, the developmental tasks and dyadic issues of adolescent daughters (aged 13–19) and their midlife mothers (aged 35–55) are examined from a psychodynamic perspective. The authors posit that both mother and daughter are experiencing a lifecycle crisis of separation and self-definition. Drawing from psychoanalytic and lifespan developmental literature as well as their own clinical experience, the authors propose that the current generation of mothers and daughters requires a new look at old models, parts of which may still be relevant and parts of which need to be revised or dropped. The issues of competition and rebellion as they relate to separation and self-definition are also addressed.