Response selection processes for conjunctive targets.

A model is proposed for identification and response selection of cross-dimensional conjunctive stimuli. The model assumes that the formation of conjunction representations involves processes similar to those used in response selection for single-feature targets. It predicts that discrimination between conjunctive targets leads to separate competitions in each of the relevant component dimensions and that detection of a predefined single conjunctive target is done at the conjunctive map level. Experiments 1 and 2 support these two sets of predictions. Experiment 3 demonstrates that responses to conjunctions of features within the orientation dimension are qualitatively different from those for cross-dimensional conjunctive targets. It is speculated that line-orientation conjunctions are handled by the visual object-recognition system, whereas cross-dimensional conjunctions, as exemplified by the model, may be performed by a different system that is closely associated with response selection processes.