Academic journal article Memory & Cognition

A Mixed-Handed Advantage in Episodic Memory: A Possible Role of Interhemispheric Interaction

Academic journal article Memory & Cognition

A Mixed-Handed Advantage in Episodic Memory: A Possible Role of Interhemispheric Interaction

Article excerpt

Recent behavioral and brain imaging data indicate that performance on explicit tests of episodic memory is associated with interaction between the left and right cerebral hemispheres, in contrast with the unihemispheric basis for implicit tests of memory. In the present work, individual differences in strength of personal handedness were used as markers for differences in hemispheric communication, with mixed-handers inferred to have increased interhemispheric interaction relative to strong right-handers. In Experiment 1, memory for words was assessed via recall or word fragment completion. In Experiment 2, memory for real-world events was assessed via recall. Results supported the hypothesis, in that mixed-handers displayed better episodic memory in comparison with strong right-handers.

Christman and Propper (2001), in part on the bases of previous imaging literature (Cabeza & Nyberg, 2000; Tulving, Kapur, Craik, Moscovitch, & Houle, 1994) and previous examinations of split-brain patients (Cronin-Golomb, Gabrieli, & Keane, 1996; Zaidel, 1995), proposed that within Tulving's (1985, 1986) episodic-semantic memory framework, explicit tests of episodic memory involve greater corpus callosum-mediated interhemispheric interaction than do implicit tests of memory. In support of this hypothesis, Christman and Propper reported that individuals with familial left-handedness, a characteristic associated with lesser cerebral asymmetry and greater interhemispheric interaction (see, e.g., Gorynia & Egenter, 2000; Marino & McKeever, 1989; McKeever, Van Deventer, & Suberi, 1973), demonstrated superior performance on a test of episodic recall, in comparison with individuals without familial left-handedness. In a subsequent experiment, inter- versus intrahemispheric processing was directly manipulated by sequentially presenting stimuli to either the same visual field or different ones. Better episodic memory was associated with between-hemispheres presentation (different visual fields) of input, but semantic memory was superior for within-hemisphere presentations (same visual field); these results further support the hypothesis that interhemispheric interaction is associated with superior episodic memory (Christman & Propper, 2001).

Recently, Christman, Garvey, Propper, and Phaneuf (2003) demonstrated increased episodic memory for laboratory stimuli as well as for real-world autobiographical memories in individuals who had undergone a manipulation that has been proposed to increase interhemispheric communication. Specifically, it has been suggested that bilateral saccadic eye movements could temporarily increase interhemispheric interaction, and that this would in turn result in increased episodic memory. The rationale behind the eye movement manipulation derives from the fact that lateral eye movements result in selective activation of the contralateral hemisphere (Bakan & Svorad, 1969). It was thus assumed that bilateral eye movements would result in bilateral hemispheric activation, which in turn was hypothesized to facilitate interhemispheric interaction, and hence episodic memory.

In Christman et al.'s (2003) Experiment 1, participants who made saccadic left-right horizontal eye movements were better able to recognize previously presented words (episodic task) than were participants who made vertical or smooth pursuit eye movements. Furthermore, increased episodic memory ability following bilateral eye movements was not matched with increased implicit memory (as reflected in a word fragment completion task); that is, bilateral eye movements did not generally enhance overall performance, but rather enhanced only recognition of episodic-type memories, supporting the hypotheses that bilateral stimulation may increase interhemispheric interaction and that interhemispheric interaction is associated with increased episodic, but not implicit, memory performance.

In their Experiment 2, Christman et al. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.