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J M Sinnott

Publications and source records attributed to J M Sinnott.

26 records · Page 2Linked to original sources

Modes of perceiving and processing information in birdsong (Agelaius phoeniceus, Molothrus ater, and Homo sapiens).

In a previous study I examined the abilities of red-winged blackbirds and brown-headed cowbirds trained with a go-right/go-left procedure to identify conspecific and alien song themes (Sinnott, 1980). Results showed that each bird species exhibited superior identification of conspecific final "trill" or "whistle" elements, relative to the alien species. The present study extends these results by examining human perception of these same song stimuli, by examining the effects of tutoring birds with alien final song elements, and by using latency analyses to investigate processing modes that are not apparent from analyses of percent-correct scores. Results suggest three different processing modes: First, humans attend primarily to the final song elements. Second, birds identifying alien songs attend primarily to the introductory elements and disregard information in the final elements. Third, birds identifying conspecific songs process both the initial and final elements, but their response latencies indicate that they direct their attention primarily to the initial elements and process the final elements without investing more time than do the alien birds that fixate on the initial elements. Conspecific special processing is discussed in relation to various psychophysical, ethological, and psycholinguistic frameworks. Human perception of birdsong is discussed in relation to backward recognition masking.

Adult↗

Frequency and intensity discrimination in humans and monkeys.

Frequency and intensity DLs were compared in humans and monkeys using a repeating standard "yes-no" procedure in which subjects reported frequency increments, frequency decrements, intensity increments, or intensity decrements in an ongoing train of 1.0-kHz tone bursts. There was only one experimental condition (intensity increments) in which monkey DLs (1.5-2.0 dB) overlapped those of humans (1.0-1.8 dB). For discrimination of both increments and decrements in frequency, monkey DLs (16-33 Hz) were approximately seven times larger than those of humans (2.4-4.8 Hz), and for discrimination of intensity decrements, monkey DLs (4.4-7.0 dB) were very unstable and larger than those of humans (1.0-1.8 dB). For intensity increment discrimination, humans and monkeys also exhibited similar DLs as SL was varied. However, for frequency increment discrimination, best DLs for humans occurred at a high (50 dB) SL, whereas best DLs for monkeys occurred at a moderate (30 dB) SL. Results are discussed in terms of various neural mechanisms that might be differentially engaged by humans and monkeys in performing these tasks; for example, different amounts of temporal versus rate coding in frequency discrimination, and different mechanisms for monitoring rate decreases in intensity discrimination. The implications of these data for using monkeys as models of human speech sound discrimination are also discussed.

Acoustic Stimulation↗

Frequency and intensity discrimination in human infants and adults.

Frequency and intensity DLs were measured in 26 human infants (ages 7-9 months) and six young adults using a repeating standard "yes-no" operant headturning technique and an adaptive staircase (tracking) psychophysical procedure. Subjects were visually reinforced for responding to frequency increments, frequency decrements, intensity increments, or intensity decrements in an ongoing train of 1.0-kHz tone bursts, and stimulus control was monitored using randomly interleaved probe and catch trials. Infants were easily conditioned to respond to both increments and decrements in frequency, and DLs ranged from 11-29 Hz, while adult DLs ranged from 3-5 Hz. Infants also easily discriminated intensity increments, and DLs ranged from 3-12 dB, while adult DLs ranged from 1-2 dB. No infants successfully discriminated intensity decrements, although adults experienced no difficulty with this task and produced DLs similar to those for increments. The apparent inability of infants to discriminate intensity decrements suggests that the infant CNS may not be well adapted to monitor rate decreases in populations of peripheral auditory neurons.

Acoustic Stimulation↗

Aspects of frequency discrimination in passerine birds and pigeons.

With the use of a positive reinforcement operant technique, pulsed-tone, frequency difference limens (DLs) were measured in two Icterid passerine species, the redwing blackbird (Agelaius phoeniceus) and the brown-headed cowbird (Molothrus ater). Direct comparisons were made with two nonpasserine control (pigeon) subjects. Blackbirds were more sensitive than pigeons to frequency changes above 1.0 kHz but less sensitive below 1.0 kHz. Measured DLs in all these birds were within the range of nonhuman mammals but higher than those of humans. The lowest delta f/f ratio for all birds occurred at 4.0 kHz, a frequency for which they exhibit minimal absolute auditory thresholds and which is a dominant component in the song of the redwing. As in humans, blackbird sensitivity at 1.0 and 2.0 kHz declined as sensation level (SL) was decreased, but at 4.0 kHz, sensitivity showed no clear dependence on SL. At 8.0 kHz, near the upper limit of blackbird hearing, sensitivity increased with a decrease in SL. This latter frequency is a dominant component in the song of the cowbird. Differences in frequency sensitivty were also found as a function of the direction of frequency shift from the standard: Upward shifts produced lower DLs at 1.0 and 2.0 kHz, and downward shifts produced lower DLs at 8.0 kHz.

Animals↗

Auditory intensity discrimination in blackbirds and pigeons.

Redwing blackbirds, brown-headed cowbirds, and pigeons were trained with operant conditioning techniques to respond to small increases in the intensity of pulsed tone trains at three frequencies: .5, 1.0, and 2.0 kHz. All three species produced similar intensity difference limens (DLs) at the frequencies tested. Intensity DLs decreased as sensation level (intensity level above absolute threshold) increased at all three frequencies, with the slopes of these sensation level functions being greatest at 2.0 kHz . The median intensity DLs at 50 dB sensation level were 3.3, 2.7, and 2.9 dB at .5, 1.0, and 2.0 kHz, respectively, averaged over the three species. Some subjects were also required to detect decreases in intensity. They produced intensity DLs two to three times larger than the DLs obtained when these same subjects were required to detect increases in intensity. Avian intensity DLs generally appear to be 1-2 dB higher than the DLs of those mammals that have been tested (rat, cat, monkey, humans).

Animals↗

Behavioral and physiological studies of hearing in birds.

Studies of hearing thresholds and frequency- and intensity-difference limens for birds are reviewed. Where possible these are related to limitations placed on auditory function by stimulus processing at peripheral levels of the avian auditory system. The high frequency limit of bird hearing is about 10 kHz; this limit is shown to be imposed in part by middle ear function and in part by cochlear mechanisms. For frequencies greater than 1.0 kHz, frequency-difference limens (DLs) show a similar dependence on frequency in birds as in mammals. Correspondingly, cochlear filtering is shown to be as good in birds as in mammals. At frequency below 1.0 kHz, frequency DLs in birds are poorer than in mammals. These low frequency differences may not be attributable to peripheral processing. Intensity-difference limens are worse in birds than mammals; there seem to be no differences in peripheral processing between birds and mammals which can account for this behavioral difference. Finally, complexities in processing at higher levels of the avian auditory system which have been related to detection of species-specific vocalizations are shown to appear in the first brainstem auditory nuclei.

Acoustic Stimulation↗