Search

In light of the controversy about the linguistic properties of chimpanzee signing behavior, the recent sign use of 5 chimpanzees (Pan troglodytes) with long histories of sign use was analyzed while they interacted with longtime human companions. Four corpora from 1992 to 1999 consisting of 3,448 sign utterances were examined. The chimpanzees predominantly used object and action signs. There was no evidence for semantic or syntactic structure in combinations of signs. Longer combinations showed repetition and stringing of object and action signs. The chimpanzees mostly signed with an acquisitive motivation. Requests for objects and actions were the predominant communicative intentions of the sign utterances, though naming and answering also occurred. This recent sign use shows multiple differences with (early) human language.

N. Masataka (1996) reported results of an experiment in which 6-month-old deaf infants were presented with videotapes that showed 5 identical scripts signed in Japanese Sign Language by 5 deaf mothers toward their deaf infants or toward their deaf friends. The experiment demonstrated that infants showed greater attentional and affective responsiveness to infant-directed signing than to adult-directed signing. The present study explored the possibility that this same phenomenon might extend to hearing infants who have never been exposed to signed language. When the same stimulus tape as used previously was presented to 45 six-month-old hearing infants, they too showed greater attentional and affective responsiveness to infant-directed sign than to adult-directed sign. This fact suggests that infants are prepared to detect sign motherese characteristics without specific experience in the modality.

The study explored the possibility that characteristics in perception of speech sounds found in pre-verbal hearing infants might extend to perception of signed languages in congenitally deaf infants during the same period. Participants were deaf mothers (N = 17) and their deaf infants; 5 of the dyads were used to prepare the stimulus tape later shown to the remaining 12 dyads. To develop the tape, the 5 mothers were observed when reciting identical scripts in Japanese Sign Language either toward their infants or toward their deaf friends. The videotape showed that mothers used signs at a significantly slower tempo when interacting with their infants than when interacting with their friends, often repeating the same sign and exaggerating the movements associated with each sign somewhat. When the stimulus tape was presented, deaf infants showed greater attentional and affective responsiveness to infant-directed signing than to adult-directed signing. The fact suggests that human infants may be equally predisposed to attend to motherese characteristics in speech or sign.

How well can a sequence of frames be represented by a subset of the frames? Video sequences of American Sign language (ASL) were investigated in two modes: dynamic (ordinary video) and static (frames printed side by side on the display). An activity index was used to choose critical frames at event boundaries, times when the difference between successive frames is at a local minimum. Sign intelligibility was measured for 32 experienced ASL signers who viewed individual signs. For full gray-scale dynamic signs activity-index subsampling yielded sequences that were significantly more intelligible than when every mth frame was chosen. This result was even more pronounced for static images. For binary images, the relative advantage of activity subsampling was smaller. We conclude that event bounardies can be defined computationally and that subsampling from even boundaries is better than choosing at regular intervals.