Visual Categorization and Object Representation in Monkeys and Humans

Abstract

We investigated the influence of a categorization task on the extraction and representation of perceptual features in humans and monkeys. The use of parameterized stimuli (schematic faces and fish) with fixed diagnostic features in combination with a similarity-rating task allowed us to demonstrate perceptual sensitization to the diagnostic dimensions of the categorization task for the monkeys. Moreover, our results reveal important similarities between human and monkey visual subordinate categorization strategies. Neither the humans nor the monkeys compared the new stimuli to class prototypes or based their decisions on conditional probabilities along stimulus dimensions. Instead, they classified each object according to its similarity to familiar members of the alternative categories, or with respect to its position to a linear boundary between the learned categories.

The Influence of Conceptual Knowledge on Visual Discrimination

“…In such experiments, similarity ratings or psychophysical discriminations differ before and after categorisation training and this difference depends on whether the judged objects were categorised into the same or different groups. After training, objects in the same group are discriminated more slowly and judged as more similar than are objects in the different group (Goldstone, 1994;Goldstone et al, 2001;Sigala, Gabbiani, & Logothetis, 2002). In these experiments, the (Dixon et al, 1998).…”

Recognition memory for realistic synthetic faces

“…Although the Wilson faces are relatively simple geometrically, they still convey sufficient information to characterize individual faces. This essential individuality, which is important in episodic memory, is absent from some commonly used face stimuli, such as Brunswik faces (Brunswik & Reiter, 1937;Peters et al, 2003;Sigala et al, 2002).…”

“…Studies of face perception and/or face memory have used a range of stimuli, including simple cartoons, such as the Brunswik faces (Brunswik & Reiter, 1937;Peters, Gabbiani, & Koch, 2003;Sigala, Gabbiani, & Logothetis, 2002), photographs collected in convenience samples from sources such as school yearbooks, or images whose properties have been tailored to the study's specific purposes (e.g., Gold, Bennett, & Sekuler, 1999). We chose to work with realistic, synthetic human faces generated using methods introduced by Wilson, Loffler, and Wilkinson (2002).…”

Generalization and similarity in exemplar models of categorization: Insights from machine learning

“…On the categorization side, ALCOVE has been used to model the behavior of neurons in inferotemporal cortex during a shape categorization task (Op de Beeck, Wagemans, & Vogels, 2001. In addition, the GCM, which does not lend itself easily to a neural interpretation, has inspired single-cell recordings in monkeys (Sigala, Gabbiani, & Logothetis, 2002;.…”