Infant psychometric functions for detection: Mechanisms of immature sensitivity

Abstract

Psychometric functions are described for individual 6- to 9-month-old infants and for individual adults for auditory detection of repeated, long- and short-duration tone bursts in quiet and for single, long-duration tone bursts in quiet and in noise. In general, infant psychometric functions have reduced upper asymptotes, shallower slopes, and poorer thresholds than adult psychometric functions. Infant-adult differences in slope and threshold are greater for short-duration tones than for other stimuli. Infant upper asymptotes are around 0.85 correct for all stimuli. One explantation for these findings is that infants are inattentive a certain proportion of time during the detection task. This model cannot account for the very shallow short-duration stimulus slope, nor can it account for infant-adult threshold differences for any stimulus. Other models of immature attention, or listening strategies, may be able to account for the slope and upper asymptote as well as the threshold of infant psychometric functions. Some combination of inattentiveness and primary neural immaturity may also account for the data. Although immaturities exist, some aspects of the detection process appear to be quantitatively similar in infants and adults.

Relationship between Intensity and Reaction Time in Normal-Hearing Infants and Adults

“…An examination of response rate as a function of level demonstrated that infants responded at least 85% of the time at each level. These response rates are consistent with the asymptotic levels for detection reported by Bargones, Werner, & Marean (1995), suggesting that the infants were performing maximally at each level.…”

Behavioral sensitivity to interaural time differences in the rabbit

“…Similar differences are found in psychometric functions between adults and infants for sound detection with level. These differences have been at least partly attributed to a lessening of "general attentiveness" (Werner and Marean, 1991;Bargones et al, 1995). When we constructed functions based on all of the tracks rather than the best 50% the thresholds increased, the curves became even more shallow and the lapse was greater, consistent with a decrease in the general attentivenss of tracks that were excluded.…”

Issues in human auditory development

“…Thus, even though the auditory system is able to filter out much of the noise surrounding the tone, the infant has difficulty extracting the tone from the noise that remains (Bargones, Werner, & Marean, 1995;Schneider, Trehub, Morrongiello, & Thorpe, 1989;Werner & Boike, 2001). As a matter of fact, 7-9-month-old infants have difficulty extracting a tone from an irrelevant sound, even when the irrelevant sound's spectrum does not overlap with the tone's spectrum (Leibold & Werner, 2006;Werner & Bargones, 1991).…”