Independence of memory for categorically different colors and shapes

Subjects carried out a difficult mental arithmetic task while viewing five colored forms. After a variable delay period, they indicated whether a randomly selected test item had a new color or shape aspect. If the test item appeared old in both aspects, then the subject indicated whether or not color and shape were conjoined as at inspection (Experiment 1). Correct mental arithmetic and recognition responses qualified the subject for monetary rewards. In Experiment 2, subjects were attentionally primed to the color or shape dimension and were asked to indicate if the test item was old or new along that dimension. The nonattended dimension acted either as a recognition facilitator or as a distractor. The stimulus features were categorically different within dimensions, and naming was inhibited by resource competition from the arithmetic task. Under these conditions, complete independence of the visually mediated memory for form and color was observed. In Experiment 1, memory for color-shape conjunctions was totally absent, and in Experiment 2, neither facilitation nor inhibition was observed as the nonattended dimension was varied.