Great expectations: Temporal expectation modulates perceptual processing speed

In a crowded dynamic world, temporal expectations guide our attention in time. Prior investigations have consistently demonstrated that temporal expectations speed motor behavior. We explore effects of temporal expectation on perceptual speed in three nonspeeded, cued recognition paradigms. Different hazard rate functions for the cue-stimulus foreperiod were used to manipulate temporal expectations. By computational modeling we estimated two distinct components of visual attention: the temporal threshold of conscious perception (t? ms) and the speed of subsequent encoding into visual short-term memory (v items/s). Notably, these components were measured independently of any motor involvement. The threshold t? was unaffected by temporal expectation, but perceptual processing speed v increased with increasing expectation. By employing constant hazard rates to keep expectation constant over time, we further confirmed that the increase in perceptual speed was independent of the cue-stimulus duration. Thus, our results strongly suggest temporal expectations optimize perceptual performance by speeding information processing. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Cross-sequential analysis of genetic influences on cognitive ability in the swedish adoption/twin study of aging

Abstract

Cross-sequential methods of analysis were applied to cognitive data from the Swedish Adoption/Twin Study of Aging. Thirteen measures of cognitive ability assessing four major domains (verbal, spatial, memory, and perceptual speed) were collected at two times of measurement separated by a three-year interval. Data were available from 41 pairs of monozygotic twins reared apart (MZA), 54 pairs of monozygotic twins reared together (MZT), 86 pairs of dizygotic twins reared apart (DZA), and 73 pairs of dizygotic twins reared together (DZT) ranging in age from 41 to 84 years. Cross-sectional differences and longitudinal changes in total variance and sources of variance were examined. With a few exceptions, both cross-sectional and longitudinal stability were found for total variance. In addition, few cross-sectional differences and longitudinal changes were found for genetic and environmental components of variance.