Abstract
The interference model supports a limited capacity of working memory (WM): if multiple to-be-remembered objects are presented in succession, features of later objects interfere with the recall of features of earlier objects. Feature recall of earlier objects can be strengthened with rehearsal, but this is possible for a limited amount of information. We investigated whether rehearsal can reduce interference in the recall of features of a single object. In the current study (N=24),a circle was presented with randomly varying color, size, and location over 400 trials. Within a single trial, the stimulus appeared followed by two sequential response screens. We probed the recall of color and location of the circle, and considered two conditions (repeat, non-repeat) to investigate recall accuracy. In the repeat condition, participants recalled one of the features (either color or location) twice in a row. In the non-repeat condition, each feature was probed in succession, in random order. Both conditions occurred on randomly intermixed trials. Recall precision for color was measured by mouse-click on a colorwheel, which rotated every time color was probed. For location, participants made a mouse-click at the estimated center of the stimulus position. We calculated z-scores for every error of recall for all participants and conducted n-way within-subjects repeated-measures ANOVA, where the factors were object feature (color, location), trial condition (repeat, non-repeat), and position of the question asked (first, second). The results showed a main effect of the position of the question asked, and a significant interaction between all factors. Although the presentation of a color wheel should arguably cause perceptual interference, color judgments were not impaired as much by repeated questioning, whereas location judgments were most impaired by the non-repeat condition. These results are opposite to those predicted by an interference model, and we propose other factors involved in WM decay.