Do some gestures have different meanings for different individuals?

Following the initial analysis of meaning based on how often gestures correlated with observable goals, I investigated the possibility that the observed variance in meaning might be caused by individuals who used the gestures solely towards a different goal. In this scenario, some orangutans might come to associate gesture x with meaning x, whereas others might associate it with meaning y. This proposed variability of meaning would indicate that, while the forms of most gestures might be species-typical and likely heritable, the meanings of the movements are not fixed but must be learned through association with response from different recipients (as development by ontogenetic ritualisation would predict, see Call and Tomasello 2007). If, on the other hand, variability in meaning is found to be the result of occasional variation in use by all individuals and no individual uses only the secondary meaning, then there is no support for the theory that meaning is individually learned during ontogeny.

The secondary goals of the 29 high-fidelity gestures and the 7 low-fidelity gestures were examined if at least 2 examples of a gesture were observed towards the secondary goal (Table 14). The aim was to determine whether the instances of gestures performed towards secondary goals were the product of occasional variation in use or because some individuals used only the second meaning of the gesture. Twenty-five gestures (air bite, arms up, back roll, dangle, duck lips open, embrace, fake, hit

ground/object, play face, pull hair, put object on head, raise arm, raspberry face, roll on back, shake object, simultaneous hit, somersault, swing, wave, shoo, food beg orally, pull away appendage, tandem walk, offer, and embrace pull) were observed fewer than 2 times in conjunction with any secondary goal and so were not used in analysis of secondary meaning.

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Table 14: PRIMARY AND SECONDARY MEANINGS OF GESTURES.

The table presents meaningful gestures(as defined in 3.4) along with their primary and secondary meanings (observable goals). Only gestures that were observed at least twice in conjunction with a secondary meaning were included. The numbers of individuals that exhibited the primary and secondary meanings of the gestures are listed along with the ratio of observations of the 1st and 2nd meanings for each individual that was observed using the 2nd meaning. The final column lists any commonalities amongst individuals that used the gesture more often in conjunction with the 2nd goal.

Primary meaning Gesture Secondary meaning # of indv. using 1st meaning # of indv. using 2nd meaning Observations of 1st:2nd meanings for those indv. Explanation for indvs. with 2nd meaning

Bite Stop 7 3 0:1, 0:1, 0:1 Adults

Hit Stop 11 3 4:1, 2:4, 0:1 Adults

Grab Stop 13 5 6:1, 1:3, 0:1,

0:2, 0:3

Adults

Reach Pick up 10 1 1:3 Infant

Swat Move back/ Leave 5 4 3:1, 0:1, 0:2, 0:2 Adults Affiliate /Play Touch Move back/ Leave 13 6 0:1, 0:1, 0:1, 0:1, 0:1, 0:2 Adults Nudge Stop 9 4 3:1, 1:1, 1:2, 0:1 “Move back” and “stop” easily confused by observer? Move back /Leave Push Stop 12 5 1:1, 1:2, 0:1, 0:1, 0:2 “Move back” and “stop” easily confused by observer? Seize Affiliate/ Play 6 2 8:2, 0:2 Both tokens from same

interaction Share

Mouth Affiliate/ _Play 2 2 3:2, 0:1 Stop Brush Move back/

Leave

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Table 14 displays the frequency of the secondary meanings for 11 gestures that I determined accurately predicted a single goal the majority of the time. The gestures in shaded cells are low-fidelity gestures that were used between 50% and 69% of the time towards a single goal. The unshaded gestures were used at least 70% of the times towards the same goal. The individuals using the first meaning and the number using the second meaning usually overlap as some individuals were observed using both meanings. Some gestures had tertiary meanings as well, but only primary and secondary meanings were analysed as the number of examples for tertiary meanings (and beyond) dwindled quickly. The ratio of examples of the primary and secondary meanings was listed for each individual who used the secondary meaning of a gesture.

Five gestures (bite, hit, grab, swat, touch) used primarily towards the goal

“affiliate/play” had secondary meanings of either “move back/leave” or “stop.” For these 5 gestures, the secondary meaning was used primarily by adults, while the primary meaning was used most frequently by immatures. Four of these gestures (bite, hit, grab, and swat), are energetic, aggressive movements, which are used frequently by immatures during play, but which do not feature as prominently in the affiliative interactions of older individuals. Instead, adults use these behaviours as serious threats or reprimands. It is possible that the difference in meaning associated with these gestures is an effect of infants using agonistic adult behaviours during play. Infant and juvenile orangutans often engage in rowdy wrestling play accompanied by biting and hitting. Juveniles of many species use adult behaviour during play (see Bekoff and Byers 1998). Perhaps immature orangutans have not yet come to use the gestures with agonistic goals, as others do not yet respond with subordinate actions. It is important to remember that the examples of gesture used to generate the meanings were all “successful” gestures where the outcome matched the presumed goal. As this definition relies on a gesture’s being effective in order to be included in the analysis, it is possible that immatures do use these gestures to attempt to repulse other individuals but are unable to achieve their goals because of their lack of dominance.

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The fifth “affiliate/play” gesture (touch) to have an agonistic secondary meaning was also used primarily by adults when employed towards its secondary goal. However, touch was the most ambiguous of the five as it was used frequently in conjunction with 6 of the 9 possible observable goals (Table 7). Two of the individuals who used touch with its secondary goal “move back/leave” used the gesture towards another non-primary goal as well, and none of the others were observed using touch more than once (with an observable goal). Because of this extreme ambiguity, this gesture is less likely to have an adult meaning and a juvenile one, and might instead be considered to be a truly

ambiguous “catch-all” gesture. If this is the case, then the observed meaning

“affiliate/play” is likely a product of the high frequency of the goal rather than a true meaning of the gesture. It seems that touch is more ambiguous than most gestures and most likely derives its meaning (when one is clear) from its context rather than its form or the status of its signaller. This extreme flexibility and reliance of contextual cues for meaning is very similar to deictic gesture (such as pointing) in humans (McNeill 1992). It is possible that touching in orangutans is similar to pointing in humans as it draws

attention to the signaller’s intent to communicate something in a particular context rather than transmitting semantic information removed from contextual clues. If this is the case, then touching may be related to the “contact gestures” produced by gorillas (Gómez et al. 1993), but the use of touching by orangutans seems to be much less directed and specific. Is it is unlikely that touching is used to direct the attention of others to external entities, as pointing is in human infants (Liszkowski et al. 2004).

One infant used reach towards his mother when he wanted to be carried. He was also observed using reach to mean “affiliate/play,” but used the gesture most commonly used prior to being picked up. It is possible that this infant learned to associate the gesture with both meanings, or that his mother responded most frequently to his affiliative

gesture by picking him up. Since he did not use the gesture exclusively with the

observable goal “pick up,” and there are not enough examples of the gesture to analyse further variables, there is not enough evidence to conclude that this infant learned a different meaning for a common gesture. The infant’s mother was the most “worried” of all mothers in the study—she kept her infant close and nervously slapped him as he was

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held against her chest when the adult male approached. It is likely that this mother reacted more immediately to requests for affiliation or carrying from her infant, possibly resulting in the infant having increased success of gestures with the goal “pick up.” Without further examples of this gesture from this infant, I am unable to draw any conclusions as to the ontogeny of meaning.

The two gestures that were used towards the primary goal of “move back/leave” (nudge and push) both had “stop” as their secondary goal. They displayed similar ratios of use between the primary and secondary meanings and had no apparent common traits of individuals who used the gestures more often towards the secondary meaning. I suspect that the ambiguity present in both of these gestures is a product of experimenter error rather than a change in meaning. The goals “move back/leave” and “stop” can be highly similar, particularly when a gesture is directed at an individual who is attempting to affiliate with the signaller. It is difficult to discern if an adult signaller wants the infant that is pulling on her arm to go away or merely to let go; and, indeed, the orangutan herself might not distinguish between the two goals in this case. However, “move back/leave” would necessarily be the goal during acts of displacement, while the goal “stop” seems more likely to occur in situations where one individual attempts to dissuade rather than displace another. I suspect that these goals are distinguishable in some cases and not distinguishable in others leading to the observed ambiguity in meaning.

The secondary meaning of seize was “affiliate/play” and, unsurprisingly, the observed use of the secondary meaning occurred during object play such as tug-of-war. Since one of the two individuals who used the secondary meaning used the primary meaning more often, and the 2 instances in which another individual used the secondary meaning came from the same play session, I do not think that the gesture has a different meaning for these 2 individuals.

The final two gestures, mouth and brush, were not used frequently enough towards the secondary goal to draw any conclusions. Mouth was used towards its secondary goal “affiliate/play” by two individuals, one of who used mouth more

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frequently towards its primary goal and the other of whom was only observed to use it once (towards the secondary goal). Brush was also used by two individuals in

conjunction with its secondary meaning, “move back/leave.” Both individuals used the gesture with its primary and secondary meanings, so the presence of the secondary meaning could result from true ambiguity of the gesture or, as was proposed for nudge and push, the discrepancy could be a product of experimenter error in distinguishing the two goals.

From this comparison of primary and secondary meanings, there is no good evidence that meanings are culturally transmitted. It appears that when gestures are used in conjunction with a secondary meaning, it is not because some individuals have learned a different meaning for the gesture, but rather a result of true ambiguity of meaning, or a reflection of changing social motivation. Social variables play an essential role in

determining the meaning of gestures. Section 3.6 in this charter explores the effect of the signallers’ age on the gestures they use. Variables such as the age of the signaller or the relationship between signaller and recipient can lead to differences in meaning for the same gesture. This change reflects both changing social goals and effectiveness at achieving different results. The meaning of some gestures does differ between

individuals, but it appears to do so generally as orangutans age, rather than as a product of cultural context. Meaning, it seems, is as universal as form in orangutan gestures.