Development of temporal integration in newborn chickens

The development of temporal integration was investigated in young chickens who momentarily delay their ongoing peeps when they hear a sound. An adaptive procedure was used to estimate absolute thresholds of pure tones and bands of noise between 10 and 460 ms in duration. Over 400 animals were tested at 0 and 4 days posthatch in a variety of conditions and controls. Thresholds decrease approximately 6 dB per doubling of duration. No difference in temporal integration was observed at low frequencies over this early postnatal period. Thresholds improved with age at higher frequencies, as expected, but only at long durations. This suggests that sensitivity may mature to long before short stimuli. A speculative hypothesis extends this idea and may explain data from chickens and humans.