INFLUENCE OF ACOUSTIC EXPERIENCE ON THE ONTOGENY OF FREQUENCY GENERALIZATION GRADIENTS IN THE CHICKEN

Describes 3 experiments with a total of 269 White Leghorn hatchling chickens (Gallus domesticus). Exp I investigated the role of auditory experience in the ontogeny of perceptual coding. Auditory frequency generalization gradients were determined by using a habituation-generalization paradigm and an orienting response. One-day and 3-4 day old Ss were habituated to 800-Hz tones and then tested at 5 frequencies ranging from 800 to 1,000 Hz. One-day-old Ss displayed reliably flatter generalization gradients than 3-4 day old Ss. Exp II used an auditory deprivation method in which an ear impression compound was injected into the external ear. Exp III also used this method to investigate deprivation on perceptual sharpening. Ss were deprived from Embryonic Day 181/2 to 3-4 days posthatch, at which time normals deprived, and sham-operated Ss were tested as in Exp I. The generalization gradients were significantly flatter than those of the 3-4 day old normal and sham-operated Ss and were similar to those of 1-day-old Ss. This effect cannot be attributed to operative procedures, changes in auditory thresholds, or changes in response rate with age or condition. Thus the perceptual sharpening normally occurring between 1 and 3-4 days posthatch fails to occur during that time in the absence of a normal acoustic environment. (41 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1979 American Psychological Association.