The International Journal of Comparative Psychology is sponsored by the International Society for Comparative Psychology. It is a peer-reviewed open-access digital journal that publishes studies on the evolution and development of behavior in all animal species. It accepts research articles and reviews, letters and audiovisual submissions.
Volume 4, Issue 1, 1990
Several methodologies are available to evaluate how animals discriminate and perceive stimuli. These methodologies are described herein, and the kinds of questions that can be addressed with each technique, and its strengths and limitations,are addressed. De ction and discrimination studies are described that measure animal abilities, followed by classification and judgment studies that measure animal proclivities. The choice of methodology is a consideration in experimental design, because the format of the question can direct, and sometimes define the answer. The experiments discussed emphasize that animals have multiple processing modes available to them that they use to classify stimuli. Detection and discrimination experiments may tap into one of those modes, while categorization and judgment experiments may address a different mode. A feature of these experiments is that they reduce the extent to which we view animal perception and cognition as distinct from human perception and cognition. Several methodologies are available to evaluate how animals discriminate and perceive stimuli. These methodologies are described herein, and the kinds of questions that can be addressed with each technique, and its strengths and limitations, are addressed. Detection and discrimination studies are described that measure animal abilities, followed by classification and judgment studies that measure animal proclivities. The choice of methodology is a consideration in experimental design, because the format of the q estion can direct, and sometimes define the answer. The experiments discussed emphasize that animals have multiple processing modes available to them that they use to classify stimuli. Detection and discrimination experiments may tap into one of those modes, while categorization and judgment experiments may address a different mode. A feature of these experiments is that they reduce the extent to which we view animal perception and cognition as distinct from human perception and cognition.
In the superior temporal sulcus (STS) of the macaque brain there are populations of cells which respond selectively to faces. Studies of these cells reveal that they are very sensitive to the direction of eye gaze and posture of the head of other subjects. It is argued that one function of the cells is to enable analysis of where other individuals are directing their attention. Given this selectivity for complex socially relevant stimuli it is surprising that the STS contains cells that respond to touch anywhere on the body or to any movement seen in the visual environment. We have investigated these tactile and motion sensitive cells to determine their behavioural significance. In the awake, behaving monkey we found that the critical dimension for polymodal coding is whether or not the sensations are expected. Tactile stimulation out of sight cannot be predicted and elicits neuronal responses. By contrast, when the monkey can see and, therefore, predict impending contact, or when the monkey touches a familiar surface in a predictable location, cell responses are reduced or abolished. In an analogous way some cells are unresponsive to the sight of the monkey's own limbs moving but respond to the sight of other moving stimuli. Since unpredictable sensations are often caused by other animals, the STS area appears well suited to defining sensory stimuli that are important in social or predator/prey interactions.
Perception of Species-specific Vocalizations by Isolate-reared Buegerigars (Melopsittacus undulatus)
Budgerigars were trained with operant conditioning procedures to discriminate among sets of calls from several species in a Same-Different task. Response latencies from this task were analyzed in several ways including multidimensional scaling (MDS) and cluster analysis. The pattern of response latencies from budgerigars reared in a large group of conspecifics was compared to that of budgerigars reared in acoustic and social isolation. Results show that budgerigars with previous experience with species-specific vocalizations and isolate-reared birds who had never heard such sounds can both discriminate among the categories of species-specific vocal signals. But, results from MDS and cluster analysis also show that rearing budgerigars in isolation has subtle effects on the perception of these categories of vocal signals.
The Perception of Complex Acoustic Patterns in Noise by Blue Monkey (Cercopithecus mitis) and Human Listeners
monkeys (Cercopithecus mitis) were trained to detect
embedded in noise. Masked thresholds were determined for four hu
sounds (6a, pa, ga, and ka), and four blue monkey
pyow, chirp, and trill). The ability of monkey listeners to hear these
was compared with humans. Results showed that monkey and human
very similar. The mean difference between species for these eight stimuli in
noise environment was 2.3 dB. The signal-to-noise ratio for
4.8 dB for the ka to -23.8 dB for the boom. The four monkey calls
at a signal-to-noise level that was 8.1 dB less than that required for the
the speech sounds. However, most of this effect was due to the audibility of
With the boom excluded, the mean signal-to-noise ratio for detection of the re
sounds was -0.5 dB, and the mean difference in the audibility of
monkey sounds within this set was 2.6 dB. These results contrast
which used simulated rain forest noise as the masking noise (Brown, 1986).
forest noise, test signals were audible at signal-to-noise ratios approximately
less than those reported here, and the observed difference in the
human and monkey utterances was larger. These findings
the amplitude and spectrum of the ambient noise may have
audibility of vocal signals in nature.
suggest that rather small
infants' perception of tone sequences or melodies is reviewed
of related work with human adults and nonhuman species. For the
infants use an adult-like pitch processing strategy that is global and
than the local pitch strategy that is characteristic of the nonhuman species stud
date. Thus they encode and retain the pitch configuration or contour of
little attention to the absolute pitches of individual notes. In the case
specifically, melodies that are prototypical of Western music, in
more precise relations, notably the intervals or exact pitch relations be
notes. Finally, the functional significance of relational pitch
human infancy is
This paper discusses timing behavior as measured by Fixed (FI), Differential Reinforcement of Low rate (DRL) or Differential Reinforcement Response Duration (DRRD) performances, in humans and animals at different develop stages. Infants and rats display similar behavior patterns in FI and childhood on, humans develop species-specific behavior patterns in FI, which differ from those of animal species. However, DRL patterns do follow similar trends in animals and humans. These discrepancies and similarities may by the availability of cognitive and linguistic tools in humans, and the degree od schedule constraint on behavior. Motivation and reinforcer variables as well as to a cross-specific timing mechanism (such as scalar timing) are briefly commented upon. Available data tend to show that humans shift from contingency-shaped or "animal-like" behavior, in infancy, to rule-governed behavior. This transition is progressive and does not seem to erase forms of adaptation to temporal constraints that humans share with other species.
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