Age differences in negative priming, episodic memory and frontal lobe tasks: a single inhibitory deficit ?

The present investigation aimed to assess whether a generalised inhibitory breakdown (Hasher & Zacks, 1988) can account for the well-documented age-related episodic memory deficits. It was argued that, according to whether significant correlations were found among all or between some of the measures of episodic memory and of inhibition included in the present investigation, it would be possible to assume that either a general or a specific, for instance, frontal lobe dependent inhibitory deficit (Dempster, 1992), was responsible for age-related memory deficit. At an empirical level, results from this investigation complement the large number of studies indicating an episodic memory deficit and an early deterioration of frontal lobes in the elderly. At a theoretical level, however, the failure to find age-related differences in the negative priming task challenges the hypothesis that cognitive ageing is due to a generalised inhibitory deficit. Furthermore, the failures to find significant correlations among performance on different tasks assumed to reflect the operation of inhibition processes support the hypothesis for the existence of multiple dissociable inhibitory processes (e.g., Kramer, Humphrey, Larish, Logan, and Strayer, 1994).