Ronald G. Weisman

A behavior analysis of absolute pitch: sex, experience, and species.

Absolute pitch (AP) perception refers to the ability to identify, classify, and memorize pitches without use of an external reference pitch. In tests of AP, several species were trained to sort contiguous tones into three or eight frequency ranges, based on correlations between responding to tones in each frequency range and reinforcement. Two songbird species, zebra finches and white-throated sparrows, and a parrot species, budgerigars had highly accurate AP, they discriminated both three and eight ranges with precision. Relative to normally reared songbirds, isolate reared songbirds had impaired AP. Two mammalian species, humans and rats, had equivalent and weak AP, they discriminated three frequency ranges to a lackluster standard and they acquired only a crude discrimination of the lowest and highest of eight frequency ranges. In comparisons with mammals even isolate songbirds had more accurate AP than humans and rats.

Call-note discriminations in black-capped chickadees (Poecile atricapillus).

Bioacousticians (M.S. Ficken, S. R. Ficken, & S. R. Witken, 1978) classified black-capped chickadee call notes from the chick-a-dee call complex into 4 note types (A, B, C, and D) identified from sound spectrograms. In Experiment 1, chickadees (Poecile atricapillus) learned operant auditory discriminations both within and between the 4 note types but learned the between note-type discrimination significantly faster. In Experiment 2, when the original, unrewarded between-category exemplars were replaced with novel, rewarded exemplars of these same categories, chickadees showed transfer of inhibitory stimulus control to the novel exemplars. In Experiment 3, when novel exemplars were replaced by the original exemplars, chickadees showed propagation of positive stimulus control back to the original exemplars. This evidence suggests that chickadees and bioacousticians accurately sort conspecific call notes into the same open-ended categories (R. J. Herrnstein, 1990).

Note types and coding in parid vocalizations. III: The chick-a-dee call of the Carolina chickadee (Poecile carolinensis)

Species of the genus Poecile Kaup, 1829 (the chickadees) are well suited to comparative studies of acoustic communication because their songs and calls occur in similar contexts and are acousticall...

Effects of songs and calls on ZENK expression in the auditory telencephalon of field- and isolate-reared black capped chickadees.

We examined the effects of hearing two different conspecific vocalizations on expression of the immediate-early gene ZENK in the caudomedial neostriatum (NCM) and the caudomedial portion of the ventral hyperstriatum (cmHV) in male and female black-capped chickadees (Poecile atricapilla). Both the fee-bee song and the chick-a-dee call induced Zenk protein expression in NCM and in cmHV, however, patterns of expression to songs and calls varied across brain region. In the dorsal region of NCM, fee-bee songs induced more Zenk expression than chick-a-dee calls. In ventral NCM and cmHV, Zenk expression did not differ between songs and calls. We found that sex of the listener also affected Zenk expression: there was more robust ZENK response in males than in females. Finally, we compared field- and isolate-reared chickadees and found similar Zenk expression to fee-bee song in each group. These findings indicated that the type of conspecific vocalization, as well as the sex of the listener, appear to modulate IEG expression in the songbird ascending auditory pathway.

Discrimination of individual vocalizations by black-capped chickadees (Poecile atricapilla)

The auditory perceptual abilities of male black-capped chickadees (Poecile atricapilla) were examined using an operant go/no-go discrimination among 16 individual vocalizations recorded at 5 m. The birds learned to discriminate about equally well among eight male chickadee fee-bee songs and eight female zebra finch (Taeniopygia guttata) distance calls. These results do not indicate that chickadees have a species-specific advantage in individual recognition for conspecific over heterospecific vocalizations. We then transferred the chickadees to a discrimination of the same songs and calls rerecorded at a moderate distance. These results showed accurate transfer of discrimination from 16 vocalizations recorded at 5 m to novel versions of the same 16 songs and calls rerecorded at 25 m. That is, chickadees recognized individual songs and calls despite degradation produced by rerecording at 25 m. Identifying individual vocalizations despite their transformation by distance cues is here described as a biologically important example of perceptual constancy.

Sexual preferences of female zebra finches: imprinting on beak colour

Sexual preferences of adult zebra finches are influenced by early learning of parental characteristics. We studied how imprinting affects the preference of female zebra finches for male beak colour. The beaks of male and female parents were painted, 2-3 days before hatch and thereafter until the young were fledged, as follows: male red, female orange (R-O group); male orange, female red (O-R group); both male and female red (R-R group); or both male and female orange (O-O group). Females were raised by painted parents until 35 days, then visually isolated from other birds until test at 100 days. In 4-way choice tests using red- and orange-painted stimulus males, females from Groups O-R and R-O chose males with beaks painted the same colour as their fathers beak, whereas females from Groups R-R and O-O did not. We conclude that preference for male beak colour was acquired only by females reared by parents with unlike, discriminative, beak colours. The results suggest an associative learning basis for sexual imprinting.

Rationale and methodology for testing auditory cognition in songbirds.

Songbirds, and in particular zebra finches, present a wonderful opportunity to study cognition in species that have evolved specialized abilities and brain structures for auditory cognition. The authors describe the rationale, methods, and apparatus used to test the auditory perceptual and cognitive abilities of songbirds. They have developed an operant conditioning system for conducting discrimination experiments simultaneously with several songbirds. The system uses specialized single-board computers, standard personal computers, CD-ROMs, and custom-written software to present stimuli, control training, and record responses. Also, the authors describe software to produce high-quality synthesized and naturally occurring acoustic stimuli for use in studies of auditory cognition. Typical results from a challenging frequency-range discrimination are included.

Open-ended categorization of chick-a-dee calls by black-capped chickadees (Poecile atricapilla)

The authors trained black-capped chickadees (Poecile atricapilla) in an operant discrimination with exemplars of black-capped and Carolina chick-a-dee calls, with the goal of determining whether the birds memorized the calls of conspecifics and heterospecifics or classified the calls by species. Black-capped calls served as both rewarded (S+) and unrewarded (S-) stimuli (the within-category discrimination), whereas Carolina chick-a-dee calls served as S-s (the between-category discrimination) in the black-capped chick-a-dee call S+ group. The Carolina call S+ group had Carolina calls as S+s and S-s (within-category) and black-capped calls as S-s (between-category). Both groups discriminated between call categories faster than within a call category. In 2 subsequent experiments, both S+ groups showed transfer to novel calls and propagation back to between-category calls. The results favor the hypothesis that the acoustically similar social calls of the 2 species constitute separate open-ended categories.

Classification of frequencies into ranges by songbirds and humans.

We trained songbirds and humans in go/no-go discriminations among 27 tones. In the compact discrimination, S + s formed a contiguous middle range (3080-4040 Hz), and S-s formed contiguous lower (2000-2960 Hz) and upper (4160-5120 Hz) ranges. In the distributed discrimination, S + s were spread across all 3 ranges. Songbirds acquired the compact discrimination more quickly and with higher accuracy than humans. Songbirds acquired the distributed discrimination only after much extended training; humans did not acquire the distributed discrimination. Compact groups (birds and humans) accurately classified test tones spaced 60 Hz from the training tones, but the distributed groups did not. A single reversal in discrimination between tones on the boundary between the lower S- and middle S + ranges did not propagate to all the tones in either range. A neural network model provided an account of the classification of tones in songbirds and humans.

White-throated sparrows (Zonotrichia albicollis) can perceive pitch change in conspecific song by using the frequency ratio independent of the frequency difference

In the ascending songs of white-throated sparrows (Zonotrichia albicollis), the first note (Phrase 1) is sung lower than the remaining notes (Phrase 2). The production of this frequency change is more reliably predicted by the frequency ratio (Phrase 2 - Phrase 1) than by the frequency difference (Phrase 2 - Phrase 1). To determine whether sparrows use the ratio rather than the difference to identify ascending songs, we transposed a low-frequency song upward in frequency, maintaining a normal frequency difference but altering the frequency ratio, and we transposed a high-frequency song downward in the same way