Degrees of isolation and the Von Restorff effect in serial learning

Sixty college students learned by the study-recall method a serial list of 11 CVCs with the central item isolated in different degrees of perceptual enhancement: shape (Eb), shape and color (Ea), or shape, color, and size (E1); the middle three items isolated (E3); the middle five items isolated (E5); or none isolated (C) to a criterion of two consecutive errorless trials. Compared to the corresponding control items, significant facilitation of isolated item (I) occurred in all experimental conditions: The magnitude of facilitation of the I (sixth item) increased as (1) the degree of perceptual enhancement increased and (2) the number of surrounding Is decreased. The item immediately following I(s) was also significantly facilitated. The findings were accounted for in terms of Gibson’s concepts of generalization and differentiation in verbal learning.