The Units Of Selection And The Causal Structure Of The World

Genic selectionism holds that all selection can be understood as operating on particular genes. Critics (and conventional biological wisdom) insist that this misrepresents the actual causal structure of selective phenomena at higher levels of biological organization, but cannot convincingly defend this intuition. I argue that the real failing of genic selectionism is pragmatic – it prevents us from adopting the most efficient corpus of causal laws for predicting and intervening in the course of affairs – and I offer a Pragmatic account of causation itself which ultimately bears out the claim that genic selectionism misrepresents the causal structure of selective contexts.     

SPATIAL ATTENTION IN VISUAL SEARCH FOR FEATURES AND FEATURE CONJUNCTIONS

Abstract— Spatial attention was measured in visual searches tasks using a spatial probe. Both speed and accuracy measures showed that in a conjunction task, spatial attention was allocated to locations according to the presence of target features. Also, contrary to some predictions, spatial attention was used when a clearly distinguishable feature defined the target. The results raise questions about any account that assumes separate mechanisms for feature and conjunction search The probe method demonstrated here allows a very direct measurement of attentional allocation, and may uncover aspects of selection not revealed by visual search     

The relationship between early development and psychosexual behaviors in adolescent females

The relationship between early sexual maturation and the psychosexual behaviors of dating and sexual intercourse was investigated using a national sample of adolescent females aged 15 to 19. Among both black and nonblack subjects, early-maturing girls were more likely to have experienced earlier dating and coital onset than were their later-maturing peers. Blacks experienced menarche and first intercourse at earlier ages, yet dating onset at later ages. Early menarche was also associated with marriage at an early age for nonblacks, but not for blacks. These racial differences were explained in terms of diverse socialization patterns or cultural expectations. For both blacks and nonblacks, those with earlier coital experience were found to have had menarche and dating onset at earlier ages.     

Behavioral aftereffects of reinforcement and its omission as a function of reinforcement magnitude

Rats responded on a multiple fixed-interval fixed-interval schedule of reinforcement. Each complete cycle of the multiple schedule was separated from the next by a relatively long period of timeout from all schedule contingencies. A response at the end of the second component of each cycle was always reinforced with an invariant reinforcement magnitude, while reinforcement magnitude and reinforcement omission were systematically varied in the first component. Response rate in the first component was a monotonic function of reinforcement magnitude in that component. These changes in response rate in the first component did not affect response rate in the second component. When reinforcement was omitted on 50% of occasions in the first component, following reinforcement there was a reduction in response rate in the second component that was monotonically related to reinforcement magnitude. Following reinforcement omission there was an increase in response rate in the second component that was unrelated to reinforcement magnitude. When reinforcement was omitted on 100% of occasions in the first component, behavioral contrast was observed.