Hemispheric asymmetry in memory search for four-letter names and human faces

Two memory search experiments were conducted using vertically oriented four-letter names and human faces as stimuli. Subjects were required to indicate as quickly and as accurately as possible whether or not a single probe stimulus (presented for 150 msec to either the left or right visual field) was contained in a set of 2, 3, 4, or 5 items being held in short-term memory. The probe stimuli were presented alone (clear condition) or centrally embedded in a matrix of dots (degraded condition). In Experiment 1 (involving names), a right visual field/left hemisphere advantage was obtained and pinpointed at the encoding stage rather than at the memory comparison stage of the information-processing system. For Experiment 2 (involving human faces), no hemispheric advantage was readily observed. In each experiment, both the left hemisphere and the right hemisphere employed an abstract memory comparison operation from which the effects of probe degradation have been removed. These results are discussed in terms of their implications for various models of hemispheric asymmetry.     

A model of cognitive development across the life span

A model of cognitive development across the life span was proposed. A distinction was drawn between an individual's unexercised potential, which refers to the level of performance that would be expected if the individual had no exercise and/or training on the ability in question, and an individual's optimally-exercised potential, which refers to the level of performance that would be expected if the individual had optimal exercise and training. Both unexercised and optimally-exercised potential levels were proposed to increase with age up to early adulthood and decrease gradually thereafter. The region between the two types of potential, which was also suggested to increase during childhood and decrease during later adulthood, indicates the extent to which exercise and/or training can affect performance. This model was shown to be consistent with a number of different types of empirical findings.