The impact of chewing gum resistance on immediate free recall

Although the facilitative effects of chewing gum on free recall have proved contentious (e.g., Tucha, Mecklinger, Maier, Hammerl, & Lange, 2004; Wilkinson, Scholey, & Wesnes, 2002), there are strong physiological grounds, for example, increased cerebral activity and blood flow following the act of mastication, to suppose facilitation. The present study manipulated resistance to mastication, that is, chewing four pellets versus one pellet of gum, with the assumption that increased resistance will accentuate cerebral activity and blood flow. Additionally, chewing rate was recorded for all participants. In a within-participants design, participants performed a series of immediate free recall tasks while chewing gum at learning (one or four pellets) and recall (one or four pellets). Increased chewing resistance was not associated with increased memory performance, despite consistent chewing rates for both the one and four pellet conditions at both learning and recall. However, a pattern of recall consistent with context-dependent memory was observed. Here, participants who chewed the equivalent number of gum pellets at both learning and recall experienced significantly superior word recall compared to those conditions where the number of gum pellets differed.