International Journal of Comparative Psychology

Perception of song syllables taken from natural song sparrow and swamp sparrow songs was examined in five different species: song sparrows (Melospiza melodia), swamp sparrows (Melospiza georgiana), zebra finches {Taeniopygia guttata catanotis), canaries iSerinus canaria), and budgerigars (Melopsittacus undulatus). Using operant conditioning techniques, we trained these birds to discriminate among sparrow song syllables. By testing the birds on all possible pair-wise combinations of syllables, we generated "similarity" matrices for these song syllables from the birds'response latencies to detect changes in a repeating background of syllables. A number of different statistical techniques were used to examine species differences in perception including factor analysis of an inter-species correlation matrix, cluster analysis ofthe similarity matrices, and individual-differences multidimensional scaling (MDS) of the similarity matrices from each species. The spatial map of these stimuli produced by MDS revealed the perceived relations among these syllables for each species. Several acoustic measurements taken from these syllables were correlated with stimulus coordinates of the syllables in multidimensional space. These results demonstrate that natural vocal signals can be effectively used as stimuli in psychoacoustic experiments and the outcome of such experiments are likely to reveal robust species differences in perception.

Pigmented dark agouti and albino Wistar rats were compared for the effect of differentially reinforced pre-exposure to peppermint as a positive and vanilla as a negative odour cue. Both types of rat showed significantly enhanced performance on the simultaneous odour discrimination task with the same cues, when compared to control groups not pre-exposed to the odour cues. However, the pigmented rats had steeper learning curves than the albinos, with the albino controls performing significantly worse than the other groups. The results are discussed in terms of task components of cue significance and response regulation. It appeared that the response component was more difficult for the albino rats compared to the pigmented rats.

This study was conducted as a portion of a project investigating relationships among reproductive cycling, aggression, and wounding in captive chimpanzees. Changes in behavior associated with the genital swelling of 11 adult female chimpanzees socially housed in four different groups were measured using 282 hours of data gathered within a 20-month period. The females' perineal swellings were rated daily using a five-point scale indicating level of tumescence. Behaviors recorded when the animals were detumescent were compared with behaviors when their sexual swellings were maximal. In addition to the subject's genital swelling rating, two factors, the male-to-female ratio in the groups and the presence or absence of a tumescent female other than the focal animal, were also included in the analysis. Multiple regression analysis revealed significant effects of each of the three factors. Significantly higher levels of sexual behavior and lower levels of submission were associated with the tumescent stage of cycling. Scores for affiliation, aggression, abnormal behavior, inactivity, locomoting, and being followed did not vary significantly with swelling phase. Group structure (male-to-female ratios) affected affiliation, locomoting, being followed, and aggression levels. Affiliation, submission, and locomoting were influenced by the presence of a tumescent female in the group. Proximity to other adult females increased during the tumescent stage of swelling, but proximity to adult males did not change. The group structure and whether or not a tumescent female was present affected various aspects of proximity to all age/sex classes of group members. Some findings from this study may be explained by the long-term stability of group membership in the colony studied, and implications for colony management are discussed.

Book Review

Spontaneous alternation behavior edited by W. N. Dember & C. L. Richman. Springer-Verlag, New York, 1990, XII + 211 pp.

Cognitive ethology: The minds of other animals, edited by Carolyn A. Ristau. Lawrence Erlbaum Associates, Hillsdale, NJ, U.S.A., 1991, XX + 332 pp.