Working-memory modularity in analogical reasoning

Working-memory modularity in analogical reasoning Robert G. Morrison (morrison@psych.ucla.edu) Keith J. Holyoak (holyoak@lifesci.ucla.edu) Bao Truong (bt@ucla.edu) University of California, Los Angeles Department of Psychology, BOX 951563 Los Angeles, CA 90095-1563 USA Abstract We present several experiments using dual-task (DT) methodology to explore use of working memory (WM) during analogical reasoning. Participants solved verbal and figural analogy problems alone or while performing articulatory suppression (AS), spatial tapping (ST) or verbal random generation (VRG). As in other studies of relational reasoning we found that VRG disrupted both verbal and figural analogy performance. In addition, we found disruption of analogy performance by WM slave system distractors (i.e., AS and ST) consistent with the dominant modality of the analogy task. These findings are discussed with respect to Baddeley’s model of WM and other studies of WM involvement in relational reasoning. Introduction Central to the ability to reason by analogy is the ability to form and manipulate mental representations of relations between objects and events. For instance, in a verbal analogy such as: BLACK:WHITE::NOISY:QUIET the reasoner needs to form mental representations of the relation between BLACK and WHITE (black is the opposite of white) and map it to the second pair in order to verify that the analogy is appropriate. Thus, BLACK:WHITE is mapped to NOISY:QUIET and the analogy is successfully solved. It has long been assumed that this type of process requires the use of WM (cf., Baddeley & Hitch, 1974); however, until recently relatively little attention has been given to how WM limits affect analogical reasoning (Halford et al., 1994; Hummel & Holyoak, 1992; Hummel & Holyoak, 1997; Keane, Ledgeway, & Duff, 1994). In the present paper we report experiments using dual-task (DT) methodology (employed extensively by Baddeley, 1986) to study the involvement of the various modules of WM in analogical reasoning. Baddeley’s (Baddeley, 1986; Baddeley & Hitch, 1974; Baddeley & Logie, 1999) model of WM has dominated cognitive accounts of short-term memory for nearly three decades. The model consists of three components: the Phonological Loop (PL), the Visuo-Spatial Sketchpad (VSSP), and the Central Executive (CE). In Baddeley’s model the PL and VSSP are modality- specific slave systems that are responsible for maintaining information over short periods of time. Baddeley (Baddeley & Hitch, 1974) originally conceived of the CE to account for functions of WM not performed by the PL and VSSP; however, Baddeley (1986) later embraced Norman and Shallice’s (Norman & Shallice, 1986) Supervisory Attentional System as a possible model of the CE. Most recently, Baddeley (1996) has segmented the CE in an attempt to study its component processes. From this perspective the CE is responsible for (1) the capacity to coordinate performance on 2 separate tasks, (2) the capacity to switch retrieval strategies as reflected in random generation, (3) the capacity to attend selectively to 1 stimulus and inhibit the disrupting effect of others, and (4) the capacity to hold and manipulate information in long-term memory, as reflected in measures of WM span (Baddeley, 1996 p. 5). Baddeley suggests that the CE manages the work of WM while the slave systems actually maintain the information. Also central to Baddeley’s model is the concept of limited capacity. The slave systems and the CE share this limited capacity, such that increasing CE functioning would reduce the capacity of either the PL or VSSP to maintain information; however, there is evidence that each system may have its own limits as well (e.g., the PL capacity is limited by the amount of information that can be subvocally cycled in approximately two seconds). Evidence for a multi-module WM system is copious, coming from both the cognitive and neuropsychology literatures. However, relatively little attention has been paid to the implications of WM for relational reasoning particularly analogical reasoning. Review of the functions of the CE as outlined above suggests that the CE should be critical for relational reasoning. Experimental evidence has confirmed this hypothesis for deductive reasoning, with random generation (e.g., Baddeley & Hitch, 1974; Gilhooly, Logie, Wetherick, & Wynn, 1993; Klauer, Stegmaier, & Meiser, 1997) and memory load (e.g., Baddeley & Hitch, 1974; Gilhooly et al., 1993; Toms, Morris, & Ward, 1993) both interfering