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Biomedical subjects

R J Schusterman

Publications and source records attributed to R J Schusterman.

28 records · Page 2Linked to original sources
PubMed1970

Conditioned vocalizations as a technique for determining visual acuity thresholds in sea lions.

Aerial visual acuity and underwater visual acuity were measured in two sea lions (Zalophus californianus) by training them to emit click bursts if they saw a striped target or to remain silent if they saw a gray target. The closest grating spacings that could be resolved both in air and under water subtended a visual angle of 5.5 minutes of arc at a distance of 5.5 meters.

Animals↗
PubMed1968

Barking, dominance, and territoriality in male sea lions.

Experiments in which male sea lions (Zalophus californianus) were removed and reintroduced into a social group demonstrate that barking by larger males restricts movement and barking by other smaller males. Barking and aggression were primarily directed toward animals of most nearly equal size. Two 6-year-olds seeking to establish and maintain territorial status used aggressive tactics similar to those observed in breeding males in the field.

Aggression↗
PubMed1967

Attention shift and errorless reversal learning by the California sea lion.

Repeated combinations of a previously well-learned size clue preference with the previously negative form cue followed by gradual reduction of the size cue resulted in nearly errorless performance by two sea lion. on a series of nine form-discriminination reversals. Systematic insertion of probe trials, during which the size cue was not present, revealed that attention was primarily focused on the size dimension during early stages of training, when size differences were large, and then was gradually shifted to the form dimension as a function of the increasing difficulty of the size discrimination.

Animals↗
PubMed1966

Underwater vocalization by sea lions: social and mirror stimuli.

Underwater vocal response of three sea lions (Zalophus californianus) increased under conditions of social interaction. When confronted by their mirror images, two animals increased their number of vocalizations, which included "whinny" sounds, barks, buzzing, and varying patterns of click trains. Click vocalizations showed habituation and recovery when the animals were in the presence of the mirror stimulus.

Animals↗
PubMed1966

Serial discrimination-reversal learning with and without errors by the California sea lion.

A sea lion under water performed virtually without errors on a series of three form-discrimination reversals. Significant training requirements were the combining of a previously well-established size cue preference with the nonpreferred form cue, followed by the gradual reduction of the size cue until it was completely eliminated. Orienting responses reached a peak and then decreased during progressive-dimensional-change training, suggesting critical stages in the transition of attention from the size dimension to the form dimension. Further experimentation revealed that intensive training during these critical stages obviated the need to reduce very gradually the size cue. Without special training sea lions make perseverative errors on a series of form-discrimination reversals. "Emotional" or nontest-oriented behavior was associated only with the occurrence of successive errors.

Animals↗
PubMed1965

Shaping and discriminative control of underwater click vocalizations in a California Sea Lion.

A captive vea lion (Zalophus californianus) which had never before produced clicking sounds in the laboratory was first conditioned to vocalize in air and subsequently learned to emit underwater clicks. clicking was brought under control by differential reinforcement procedures. Vocalization as an indicator response may be useful in the comparative study of discriminative behavior.

Animals↗