The Heuristic and Motivational Value of Video Reinforcement

Four rhesus monkeys (Macaca mulatta) were tested on joystick-based computer tasks in which they could choose to be reinforced either with pellets-only or with pellets + video. A variety of videotapes were used to reinforce task performance. The monkeys significantly preferred to be rewarded with a pellet and 10 s of a blank screen than a pellet plus 10 s of videotape. When they did choose to see videotaped images, however, they were significantly more likely to view video of themselves than video of their roommate or of unfamiliar conspecifics. These data support earlier findings of individual differences in preference for video reinforcement, and have clear implications for the study of face-recognition and self-recognition by nonhuman primates.     

Apparatus as milestones in the history of comparative psychology

Significant apparatus developments from the history of comparative psychology are reviewed, including the contemporary trend toward computer use in research with nonhuman animals. It is argued that milestone apparatus served not only to open new lines of inquiry but also to shape or delimit the nature of the answers that were obtained.     

Testing primates with joystick-based automated apparatus: Lessons from the Language Research Center’s Computerized Test System

Nonhuman primates provide useful models for studying a variety of medical, biological, and behavioral topics. Four years of joystick-based automated testing of monkeys using the Language Research Center’s Computerized Test System (LRC-CTS) are examined to derive hints and principle for comparable testing with other species-including humans. The results of multiple parametric studies are reviewed, and reliability data are presented to reveal the surprises and pitfalls associated with video-task testing of performance.     

A computer-controlled language training system for investigating the language skills of young apes

A computer-controlled language training system was designed and constructed to enhance the objectivity and efficiency of inquiry into the language-relevant behaviors of apes. The system allows the S to gain control over the events of the 24-h day in direct correspondence with its competence in using a keyboard on which each key represents a word. Various incentives can be obtained through the selection and depression of appropriate keys in accordance with rules of sentence structure monitored by a computer. The system is flexible and allows for eventual conversation between man and ape, with the computer as the intermediary. A Teletype records all that transpires. Achievements of the chimpanzee S over the course of the first 8 months of the system’s operation attest to the worth of the system and training methods.     

Summation in the chimpanzee (Pan troglodytes)

In this research, we asked whether 2 chimpanzee (Pan troglodytes) subjects could reliably sum across pairs of quantities to select the greater total. Subjects were allowed to choose between two trays of chocolates. Each tray contained two food wells. To select the tray containing the greater number of chocolates, it was necessary to sum the contents of the food wells on each tray. In experiments where food wells contained from zero to four chocolates, the chimpanzees chose the greater value of the summed wells on more than 90% of the trials. In the final experiment, the maximum number of chocolates assigned to a food well was increased to five. Choice of the tray containing the greater sum still remained above 90%. In all experiments, subjects reliably chose the greater sum, even though on many trials a food well on the "incorrect" tray held more chocolates than either single well on the "correct" tray. It was concluded that without any known ability to count, these chimpanzees used some process of summation to combine spatially separated quantities. Speculation regarding the basis for summation includes consideration of perceptual fusion of pairs of quantities and subitization.     

Symbolization, language, and chimpanzees: A theoretical reevaluation based on initial language acquisition processes in four young Pan troglodytes

The emergence of symbolic use of word-lexigrams is traced through the course of four experiments with four chimpanzees. The results indicate that it is ill advised to begin language training by introducing the names of objects or their attributes. Training which allowed the subjects to have the machine vend foods, the names of which were on keys, facilitated the discrimination of the lexigrams moreso than did training which called for the labelling of foods held by the experimenter; however, the discriminations so established seemed to be basically associationistic—subjects were not able to use the word symbols appropriately in a communicative manner or to use the words contingent upon the presence or absence of a given food in the dispenser. Subsequent training with verb-object phrases, where the chimpanzees were able to observe all steps in the delivery of foods and drinks contingent upon correct choices among the lexigrams and the formulation of correct requests, fostered the decontextualization of lexigram usage and the symbolic uses of the words used in training. Errorless training procedures were ineffective. By the end of this training the chimpanzees were able to reintegrate and reorganize skills which, initially, had been only partially mastered, and their learning rates of new words and their extended, appropriate use thereof became strongly evidenced. Caution is extended regarding the use of “word” to a response of an ape, be it with a sign of Ameslan, a plastic token, or a lexigram. There are levels of “wordness” and the symbolic, decontextualized level is achieved only through the course of experiences which serve to emphasize the symbol-referent relationship.     

Effects of competition on video-task performance in monkeys (Macaca mulatta)

The effects of competition on performance of a video-formatted task were examined in a series of experiments. Two rhesus monkeys (Macaca mulatta) were trained to manipulate a joystick to shoot at moving targets on a computer screen. The task was made competitive by requiring both animals to shoot at the same target and by rewarding only the animal that hit the target first each trial. The competitive task produced a significant and robust speed-accuracy trade-off in performance. The monkeys hit the target in significantly less time on contested than on uncontested trials. However, they required significantly more shots to hit the target on contested trials in relation to uncontested trials. This effect was unchanged when various schedules of reinforcement were introduced in the uncontested trials. This supports the influence of competition qua competition on performance, a point further bolstered by other findings of of behavioral contrast presented here.