Biomedical subjects

L W Olsho

Publications and source records attributed to L W Olsho.

6 recordsLinked to original sources

PubMed1990

Auditory frequency resolution in human infancy.

Frequency resolution is a fundamental capacity of the auditory system that underlies the perception of all complex sounds. The development of this capacity has not been well characterized in humans. This investigation used a nonsimultaneous pulsation threshold technique to examine the development of infant frequency resolution. Psychophysical tuning curves were obtained for 3- and 6-month-olds and for adults at either 500, 1,000, or 4,000 Hz. Both the sensation level and the sound pressure level of the stimulus were varied for adults to determine the contribution of stimulus intensity to age differences in frequency resolution. At 500 and 1,000 Hz, 3- and 6-month-olds' tuning curve widths were equivalent to adults'. At 4,000 Hz, the 3-month-olds' tuning curves were broader than those of 6-month-olds and adults, even when absolute sound pressure level was equivalent. The maturation of psychophysical frequency resolution in infants is discussed in terms of the general development of the auditory system and of nonsensory factors that might contribute to age differences in performance.

Attention↗

PubMed1988

Pure-tone sensitivity of human infants.

Pure-tone thresholds at frequencies ranging from 250 to 8000 Hz were estimated for 3-, 6-, and 12-month-old infants and for adults, using the Observer-based Psychoacoustic Procedure (OPP). Sounds were presented monaurally using an earphone. Psychometric functions of infants were similar to those of adults, although 3-month-olds had shallower functions at higher frequencies. The thresholds of 6- and 12-month-old infants were 10-15 dB higher than those of the adults, with the difference being greater at lower frequencies. This result is in general agreement with results from other laboratories. The thresholds of 3-month-olds were 15-30 dB higher than those of adults. The greatest difference between 3-month-olds and adults was at 8000 Hz. This threshold difference is smaller than that reported in earlier behavioral studies; higher thresholds at high frequencies have been previously reported for newborn and 3-month-old infants. The relative contributions of sensory and nonsensory variables to these age differences are discussed.

Arousal↗

PubMed1987

Level and age effects in infant frequency discrimination.

Frequency difference limens (FDLs) were estimated for 3-, 6-, and 12-month-old infants and for adults using pure tones at 500, 1000, and 4000 Hz. Each listener provided an FDL at 40 dB and at a higher (80 dB, in most cases) sensation level (SL). An observer-based behavioral testing technique was used. The FDLs of 3-month-olds were worse than those of adults at all three frequencies, and increased with increasing frequency. The FDLs of 6- and 12-month-olds were worse than those of adults at 500 and 1000 Hz, but not at 4000 Hz. Decreasing the SL led to an increase in the FDL of about the same magnitude at all ages, and the same age differences were found at both SLs. Thus infant-adult differences in FDL are not a simple consequence of differences in absolute sensitivity. Infant FDLs at one SL were also found to be significantly correlated with the FDL at the other SL. The FDLs at one age were, in general, predictive of the FDL at a later age in a longitudinal sample of infants. Models that might account for these age-related differences are discussed.

Adult↗

PubMed1986

Auditory processing deficit in a patient with Rett syndrome.

Because of the consistent and prominent language failure in Rett syndrome, a patient with the characteristic phenotype was tested for subtle auditory processing deficits by visual reinforcement audiometry. In spite of excellent detection threshold and frequency discrimination, frequency sweep discrimination was at a chance level. This discrimination is normally performed by 5-8 month old infants. This observation suggests a defect in the specialized units of the inferior colliculus or higher auditory centers which subserve frequency sweep discrimination.

Audiometry↗

PubMed1978

Searching for multiple targets simultaneously: is it really possible?

In an attempt to clarify the findings of Neisser and his associates with respect to parallel processing of multiple target items in a visual search task, subjects were tested in a multiple-target search situation in which the various target sets were not nested. 20 sessions were run for each subject with 12 trials per day. The targets used were geometric forms, allowing for manipulation of the number of features in each form. The results do not confirm those of Neisser, in fact, the interaction of session x target-set size was in a direction opposite to that predicted by a parallel preattentive processing may in fact have reflected a tendency for subjects to scan for a master set of targets, regardless of which subset of that set was actually present on a given set.

Adult↗

PubMed1978

Use of constant target sets in visual search tasks.

54 subjects participated in a visual scanning study in which each subject was provided with only a single target set (of 1, 2, 4, 6, 8, or 10 letters in length). Eight sessions of 30 trials each were completed for each subject. Although there were slight differences in the rate at which performance improved over trials, this was not systematically related to size of target set. Moreover, even in the last session, there were large differences in performance in the different target sets. These findings suggest that Neisser's evidence for parallel preattentive processing in such tasks may have been confounded by his use of nested target sets and a within-subject design.

Adult↗