DISHABITUATION OF VISUAL-ATTENTION IN 4-MONTH-OLDS BY INFANT-DIRECTEDFREQUENCY SWEEPS

The effects on visual attention in 4-month-olds of rising, falling, an d bell-shaped frequency sweeps taken from natural, infant-directed (ID ), female speech were investigated in a habituation-dishabituation par adigm. In bath experiments, a checkerboard pattern was presented for 1 0 s on each of 12 trials, with a 10-s series of five brief sweeps occu rring simultaneously with the visual stimulus on the ninth trial. In E xperiment 1, infants exhibited renewed visual attention when rising an d bell-shaped, but not falling, frequency sweeps were presented. Renew ed attention also occurred on the subsequent (10th) trial in which the check pattern was again presented alone. However, this Thompson-Spenc er dishabituation effect occurred only following the rising sweep. In Experiment 2, visual attention increased significantly during presenta tions of both the rising and falling sweeps, and Thompson-Spencer dish abituation was again observed only following the rising sweep. Synthet ic sweep stimuli modeled on the fundamental frequency (F-0) of the ris ing sweep similarly increased gaze duration but produced no Thompson-S pencer dishabituation. Results are discussed in terms of the attention -controlling and arousing properties of ID frequency-modulated sweeps.