EARLY-HOLISTIC PROCESSING OR DIMENSIONAL SIMILARITY

In this commentary, we consider current evidence for the theory that m ultidimensional stimuli are initially processed as unanalyzed wholes. The theory appears unable to explain observers' behavior in various sp eeded and unspeeded tasks: (a) Perceivers can differentiate tiny chang es made between confusable dimensions; (b) the fits of distance metric s to rating data appear to be largely under the control of optional pr ocesses; and (c) direct predictions from early-holistic models, as ins tantiated in the Euclidean hypothesis, are disconfirmed in tests using the rotation paradigm. In contrast, evidence has mounted to support t he view that perception relies on a set of primary dimensions, process ed within context-bound constraints. D. G. Kemler Nelson (1993) has be en critical of our approach; we respond to each of her objections.