The manual pointing of 2 signing chimpanzees, Moja and Tatu, was examined in 2 experiments. Experiment 1 investigated eye-gaze direction, hand use, and hand shape while pointing. Both chimpanzees obtained the attention of a human before pointing toward an unreachable object. During 100 trials, the chimpanzees alternated their eye gaze between the object and the human while pointing. Moja's points were left-hand biased, and Tatu showed no lateral hand bias. Both indexical and whole hand points were recorded. Experiment 2 tested the chimpanzees' ability to point accurately toward objects in close proximity to each other. Humans were able to reliably determine the locations toward which the chimpanzees pointed. Both chimpanzees showed left-hand biases, and a higher proportion of indexical points were observed than in Experiment 1. These results are compared and contrasted with recent hypotheses pertaining to the topography of chimpanzee pointing and the role of eye gaze in deictic interactions.

Two male and two female chimpanzees were each taught ten signs of American Sign Language. The acquisition rates of the signs were compared on the basis of the number of minutes required in training to reach a criterion of five consecutive unprompted correct responses. After the ten signs had been acquired, the chimpanzees were tested in a double-blind procedure for nine of the signs. All four chimpanzees acquired all of the signs. Some signs were consistently easier to acquire than others, and individual differences between the four chimpanzees were found in the acquisition rates and tests.

Over a 7-month period, stick tools constructed by chimpanzees were collected and measured at the Ngotto Forest site in Central African Republic. The chimpanzees were found to use tools to dip for ants and to probe for honey. The basic descriptions of these tools and the contexts in which they were found are presented. The lengths of two of the tool types were compared with the use of a t-test for independent groups. It was found that the lengths of the tools differed significantly depending upon their function. The location and habitat type of each tool site were plotted on a map. The tool types were distributed throughout the southern part of the study area, and with one exception all tool sites were found in the same type of habitat. Two tool sites with two other types of tools (honey hammer/club and ant club) were found. The tool types at Ngotto are compared with those found at other chimpanzee field sites, and the implications for diversity in chimpanzee material culture are discussed.

Experiments in the perception and language abilities of autistic children indicate that the children have auditory-visual association problems. These findings, combined with the findings that autistic communication is primarily gestural, led to the teaching of elements of American Sign Language to a 5-year-old nonverbal autistic boy. Results after 20 hours of training indicate that the child did acquire signs, that increasing signing led to increasing vocal speech, and that the child has rudimentary English syntax. The use of Ameslan signs spontaneously generalized to other situations and the training resulted in increased social interaction.

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