Idiosyncratic gestures

For five of the gestures, no more than one individual was observed to use them intentionally. I therefore deemed these five gestures to be idiosyncratic, as only single individuals used the actions as communicative signals though others may have used similar movements in non-communicative ways. Some of these individuals used their idiosyncratic gestures to only a single recipient, others to many individuals in their group. The effectiveness of the gestures (whether or not they elicited the “intended” response) was not taken into account in determining whether these idiosyncratic gestures should be included as gestures; if they were accompanied by measures of intentional usage, they were counted as gestures, regardless of whether they ever received a response from their recipients. The five idiosyncratic gestures are listed in Table 15 along with the age class and zoo of the individuals that used them.

Table 15: “IDIOSYNCRATIC” GESTURES: GESTURES USED BY ONLY ONE INDIVIDUAL IN AN INTENTIONAL MANNER.

Gesture Count Modality Group Age Sex

Drag 4 Visual Durrell Infant M

Duck-lips (open)

11 Visual Durrell Adult M

Fake 9 Visual Twycross Adult F

Restrain 3 Tactile Apenheul Adult F

108

Appendices

As idiosyncratic gestures were observed in all three zoos, no one group seemed to have a greater propensity for developing idiosyncratic gestures.

The infant that exhibited the gesture drag, used it in dyadic contexts of attempted play or in social contexts when the attention of the others was directed elsewhere. Thus, I assume that the infant used the action as an invitation to play. The gesture was only observed a total of four times in this individual, and never achieved a response from either of the two recipients to which it was directed. It is possible that the infant was either testing out this action as a gesture for the first time or that the action had succeeded before as a gesture and the lack of response in the four observations was an abnormality. Our data do not favour one interpretation over the other. It would be necessary to see whether the infant exhibited the gesture later in life in order to determine whether it had been established as a gesture or was observed by chance being used as a gesture. Either way, the infant used drag only rarely and had many other play initiation gestures. It is likely that drag was an object-directed play behaviour that could be used as a gesture towards another individual when coupled with response waiting or other gestures.

Duck-lips-open was used by a single adult male towards one of his infant sons to initiate play. The male used the gesture 11 times, and only once did it fail to receive a positive response. I concluded that this gesture was a highly effective invitation to play when used by this male to this infant.

Fake was used by an adult female in teasing contexts with her juvenile daughter. The teasing sessions appeared to take the form of a game where the adult female would quickly strike out towards a limb of the juvenile who would quickly retract it. Then the juvenile would slowly extend the limb again and the “game” would be repeated several times. I observed the same pair engaged in this routine several times during the study. One more than one occasion, when the juvenile turned away, the mother would use a tactile gesture to regain her attention before attempting fake again.

109

Appendices

Restrain was used by an adult female at Apenheul Primate Park to cause others to stop their actions. It was a potentially physically-effective action in that the female would grasp the hand of another and hold it immobile. This action did not, however, hinder the other movements of the animal and the female never exaggerated this gesture by seizing other parts of the recipient’s body. It seems likely that this behaviour is therefore an intentional gesture more than an effective action itself as it did not fully restrict the movements of the recipient but often caused him to cease what he was doing.

Shrug was used reliably by one adult female to either of her two daughters when they were grooming or attempting to affiliate with her. I interpreted the goal of the action as a desire that the recipient to back away, as the female repeated the gesture or switched to a more specific directional gesture such as a push if the shrug received no response.

Each of the five idiosyncratic gestures was used reliably and intentionally by a single individual. The gestures also seemed to be used to achieve specific goals as each was employed in a particular context. These idiosyncratic gestures seemed to be

specialized gestures rather than generalist gestures; used for communicating one type of desire and, in two cases, to a specific individual. They were likely the effect of one individual finding that a specific movement or action elicited a desired response in another and then proceeding to use the action (or a ritualized version of the action) as a signal to others. Four of the gestures (duck-lips-open, fake, restrain, and shrug) were very effective in eliciting the intended reaction from the recipient. Drag did not appear to reliably elicit a particular reaction and it is possible that the infant who used this gesture was either “testing” the movement as a gesture, or particularly enjoyed the behaviour and persisted in using it to try to communicate despite continued failure.

110

Appendices