Teaching pigeons an abstract relational rule: insideness

In 49 sessions, pigeons failed to learn to sort a collection of 80 stimuli composed of a closed curve and a dot, divided into two categories, according to whether the dot was or was not inside the curve. Next, the pigeons were successfully trained, first with the insides of the curves shown in bright red, then with a darker red, and finally with a black matching the background outside the curve. After this stepwise procedure, the pigeons displayed a limited ability to sort novel curves and dot locations according to whether the dot was or was not inside the curve.     

Evidence for two types of spatial representations: hemispheric specialization for categorical and coordinate relations

Analyses of human object recognition abilities led to the hypothesis that 2 kinds of spatial relation representations are used in human vision. Evidence for the distinction between abstract categorical spatial relation representations and specific coordinate spatial relation representations was provided in 4 experiments. These results indicate that Ss make categorical judgments--on/off, left/right, and above/below--faster when stimuli are initially presented to the left cerebral hemisphere, whereas they make evaluations of distance--in relation to 2 mm, 3 mm, or 1 in. (2.54 cm)--faster when stimuli are initially presented to the right cerebral hemisphere. In addition, there was evidence that categorical representations developed with practice.     

Components of high-level vision: a cognitive neuroscience analysis and accounts of neurological syndromes

Neuroanatomical, neurophysiological, and computational constraints are used to motivate a set of hypotheses about the functional organization of high-level vision. A set of processing subsystems is posited that underlies the later stages of visual object recognition and identification; these subsystems have been implemented in a running computer simulation model. The model is damaged in a variety of ways, and its performance on a set of tasks is observed. Dysfunctions arise from disruptions of the subsystems, disruptions of their interconnections, compensations by intact subsystems, and diminished activational capacity. The most common dysfunctions of high-level vision following brain damage are then reviewed, and accounts are offered by reference to the stimulation model. According to the theory and model, each type of dysfunction can arise from numerous underlying causes, all of which are potentially distinguishable by empirical methods.     

Categorical versus coordinate spatial relations: computational analyses and computer simulations.

Results of 4 sets of neural network simulations support the distinction between categorical and coordinate spatial relations representations: (a) Networks that were split so that different hidden units contributed to each type of judgment performed better than unsplit networks; the reverse was observed when they made 2 coordinate judgments. (b) Both computations were more difficult when finer discriminations were required; this result mirrored findings with human Ss. (c) Networks with large, overlapping "receptive fields" performed the coordinate task better than did networks with small, less overlapping receptive fields, but vice versa for the categorical task; this suggests a possible basis for observed cerebral lateralization of the 2 kinds of processing. (d) The previously observed effect of stimulus contrast on this hemispheric asymmetry could reflect contributions of more neuronal input in high-contrast conditions.