Biomedical subjects

C R Menzel

Publications and source records attributed to C R Menzel.

4 recordsLinked to original sources

PubMed1999

Unprompted recall and reporting of hidden objects by a chimpanzee (Pan troglodytes) after extended delays.

The ability to recall features of environments not present to the senses is important in human thinking, planning, and communication, but to date there are almost no data on recall capabilities in nonverbal animals. In this study, the author used symbol knowledge as a tool to study chimpanzee memory. An 11-year-old female chimpanzee (Pan troglodytes) that had already learned a large number of arbitrarily designated geometric forms (lexigrams) watched as an experimenter hid an object in the woods outside her outdoor enclosure. The type and location of the object varied across trials. After an imposed delay of up to 16 h, the chimpanzee could interact indoors with a person who did not know that an object had been hidden, let alone the type or location of the object. A keyboard in the indoor cage displayed 256 lexigrams. From Trial 1, the chimpanzee seemed to do whatever it took to catch the person's attention and then touched the lexigram corresponding to the type of object hidden, pointed outdoors, went outdoors (if followed), and continued to point manually toward the object and vocalize until the person found the object. The subject indicated nonfood objects as well as more than 20 food types.

Animal Communication↗

PubMed1996

Spontaneous use of matching visual cues during foraging by long-tailed macaques (Macaca fascicularis).

A social group of 38 captive-born Macaca fascicularis was confined to a holding cage while food was placed in an outdoor enclosure next to a structure (e.g., stone, tree) that varied across trials. After the group was released and obtained the food, animals inspected other structures similar to the baited structure more quickly and more often than they inspected equally conspicuous nonmatching structures. Animals also varied their search according to the quality of food, remembered the exact location of food on the previous trial, and discriminated sharply between locations where other macaques found or did not find food. Use of visual cues by experimentally naive macaques seems far more efficient than would be expected from many prior laboratory studies but is consistent with wild macaque foraging behavior.

Animals↗

PubMed1986

Structural aspects of arboreality in titi monkeys (Callicebus moloch).

In nature titi monkeys spend virtually all of their time in trees. Preferences for certain heights above the ground or for trees per se are probably not, however, the immediate causes of this behavior, for animals housed in a large field cage containing many trees spend most of their time on a low-altitude artificial runway system. Further, the animals are not necessarily reluctant to touch the ground. To investigate the importance of perceived substrate structure as a determinant of arboreality, individuals were given opportunities to descend from their home runway and travel to food placed nearby on the ground. The animals travelled along a schematic model of a tree branch rather than across open ground when given a choice of these substrates, but they readily crossed the open ground when it was their only travel option. When the schematic model increased substantially in length and no longer provided a short route to food, it was still the preferred substrate. The results suggest that an abstract representation of a tree branch attracts and guides locomotion in titis, and that responsiveness to substrate characteristics contributes to arboreality in this species.

Animals↗

PubMed1980

Head-cocking and visual perception in primates.

To examine the phyletic distribution and ontogeny of 'head-cocking' (rotating the cranium about the longitudinal body axis while orienting in a fixed direction) in primates, I conducted observations on 229 individuals of 40 different species. Head-cocking in primates typically occurs during visual inspection of objects. The response is primarily characteristic of diminutive species that lack ocular dominance columns in the visual striate cortex (e.g. marmosets, squirrel monkeys), and is most frequently observed during infancy.

Animals↗