Effects of trehalose and sucrose, osmolality of the freezing medium, and cooling rate on viability and intactness of bull sperm after freezing and thawing

The effect of passively exposing infants to visual information in a sensory preconditioning paradigm was assessed in five experiments with seventy-eight 6-month-olds. In the basic paradigm, infants were simultaneously exposed to two contexts (S1 and S2), trained in one of them (S1), and tested in the other (S2). Infants learned an association between S1 and S2 and exhibited transfer to S2 after preexposures of 1 hr/day for 1 week but not after 2 min or 1 hr on a single occasion. When S1 was the focal cue, however, infants transferred responding after a single preexposure lasting only 2 min. Extended preexposure also produced learned irrelevance, biasing subsequent selective attention, but there was no evidence of latent inhibition. These findings demonstrate that young infants pick up fairly sophisticated information about specific stimuli in their visual surround and the relationships between them merely as a result of passive observation, without explicitly being trained to do so. Moreover, infants may not express this knowledge for several days, until finally given an opportunity to do so. Sensory preconditioning may be an instance of "unitization"-a special type of infantile learning that enables immature organisms to acquire some associations more rapidly than adults.