WORKING-MEMORY AND CONDITIONAL REASONING

Little is known about the role of working memory in conditional reason ing. This paper reports three experiments that examine the contributio ns of the visuo-spatial scratch pad (VSSP), the articulatory loop, and the central executive components of Baddeley and Hitch's (1974) model of working memory to conditional reasoning. The first experiment empl oys a spatial memory task that is presented concurrently with two puta tive spatial interference tasks (tapping and tracking), articulatory s uppression, and a verbal memory load. Only the tracking and memory loa d impaired performance, suggesting that these tap the VSSP and central executive, respectively. Having established the potency of these inte rference tasks two further experiments examined the effects of tapping and tracking (Experiment 2) and articulation and memory load (Experim ent 3) on a conditional reasoning task. Neither tracking nor tapping a ffected the number of inferences accepted or response latency. Articul ation also failed to affect conditional reasoning but memory load sele ctively reduced acceptance of modus tollens inferences. These results are discussed in terms of both rule-based and mental models theories o f reasoning. While these data cannot discriminate between the two pers pectives they provide support for one of the central assumptions in ea ch: that some errors in reasoning are attributable directly to working memory demands. Taken together these experiments suggest that conditi onal reasoning requires an abstract working memory medium for represen tation, it does not require either the VSSP or the articulatory loop. It is concluded that the central executive provides the necessary subs trate.