Erica Cartmill | University of California, Los Angeles (original) (raw)

Papers by Erica Cartmill

Many researchers have studied primate call systems for clues to the antecedents of human language... more Many researchers have studied primate call systems for clues to the antecedents of human language. Several species of primates use calls that have functionally referential meanings (Zuberb��hler, 2003). It has yet to be demonstrated, however, that the meanings encoded in these calls are intended by the senders. It is difficult to see how a vocal system of unintentional signals, rigid in structure and situation-specific, could have transitioned into a flexible language-like system with recombinative power.

Several lines of research indicate that spatial language is related to spatial thinking (eg, Casa... more Several lines of research indicate that spatial language is related to spatial thinking (eg, Casasola, Bhagwat & Burke, 2009; Gentner & Loewenstein, 2002).

Research Methods in …, Jan 1, 2011

Behavioural Processes, Jan 1, 2011

Here we describe the modification and use of a new tool type in the woodpecker finch (Cactospiza ... more Here we describe the modification and use of a new tool type in the woodpecker finch (Cactospiza pallida). This species is known to habitually use twigs or cactus spines to extract arthropods out of tree holes. We observed an adult and a juvenile bird using several barbed twigs from introduced blackberry bushes (Rubus niveus) which the adult bird had first modified by removing leaves and side twigs. The barbs of blackberry tools provide a novel functional feature not present in tools made from native plants and de-leafing of twigs never has been observed before. Both birds were observed using several of these tools to extract prey from under the bark of the native scalesia tree (Scalesia penduculta). They oriented the twigs such that the barbs pointed towards themselves; this rendered the barbs functional as they could be used to drag prey out of a crevice. The juvenile bird first watched the adult using the tool and then used the tool that the adult bird had left under the bark at the same location and in the same way as the adult. Our observation highlights the fact that opportunities for the transmission of social information do occur in the wild and indicates that woodpecker finches are flexible in their choice of tool material and tool modification.

The Oxford handbook of …, Jan 1, 2011

This chapter reviews primate cognitive abilities in physical, social, and communicative realms an... more This chapter reviews primate cognitive abilities in physical, social, and communicative realms and asks (1) whether primates exhibit abilities that diff er from those of other animals, and what selective pressures primates face that may have led to the emergence of specifi c cognitive abilities. The authors focus on communication as the most likely realm for primate cognitive specialization and on the gestural communication of great apes as the modality in which primates exhibit the most advanced cognitive abilities. Findings from studies of natural communication systems of both wild and captive primates as well as studies involving communication with human experimenters are presented and discussed. Apes demonstrate fl exibility, learning, and sensitivity to social cues in their gestural communication, but further studies are needed to determine how gestures are acquired and how they are perceived. Studies of comparative development of gestural communication and social cognition have the greatest potential to reveal the cognitive abilities used during gesturing, and they will help to determine whether those abilities are truly specializations for communication.

… of the Royal …, Jan 1, 2012

The movements we make with our hands both reflect our mental processes and help to shape them. Ou... more The movements we make with our hands both reflect our mental processes and help to shape them. Our actions and gestures can affect our mental representations of actions and objects. In this paper, we explore the relationship between action, gesture and thought in both humans and non-human primates and discuss its role in the evolution of language. Human gesture (specifically representational gesture) may provide a unique link between action and mental representation. It is kinaesthetically close to action and is, at the same time, symbolic. Non-human primates use gesture frequently to communicate, and do so flexibly. However, their gestures mainly resemble incomplete actions and lack the representational elements that characterize much of human gesture. Differences in the mirror neuron system provide a potential explanation for non-human primates' lack of representational gestures; the monkey mirror system does not respond to representational gestures, while the human system does. In humans, gesture grounds mental representation in action, but there is no evidence for this link in other primates. We argue that gesture played an important role in the transition to symbolic thought and language in human evolution, following a cognitive leap that allowed gesture to incorporate representational elements.

American Journal of Medicine, Jan 1, 2011

The use and manufacture of tools has been considered to be cognitively demanding and thus a possi... more The use and manufacture of tools has been considered to be cognitively demanding and thus a possible evolutionary driving factor of intelligence. Animal tool use provides the opportunity to investigate whether the use of tools evolved in conjunction with enhanced physical cognitive abilities. However, success in physical tasks may simply reflect enhanced general learning abilities and not cognitive adaptations to tool use. To distinguish between these possibilities, we compared general learning and physical cognitive abilities between the tool-using woodpecker finch, Cactospiza pallida, and its close relative, the small tree finch, Camarhynchus parvulus. Since not all woodpecker finches use tools, we also compared tool-using and nontool-using individuals, predicting that domain-specific experience should lead tool-using woodpecker finches to outperform nontool-users in a task that is similar to their natural tool use. Contrary to our predictions, woodpecker finches did not outperform small tree finches in either of the physical tasks and excelled in only one of the general learning tasks, and tool-using woodpecker finches did not outperform nontool-using woodpecker finches in the physical task closely resembling tool use. Our results provide no evidence that tool use in woodpecker finches has evolved in conjunction with enhanced physical cognition or that domain-specific experience hones domain-specific skills. This is an important contribution to a growing body of evidence indicating that animal tool use, even that which seems complex, does not necessitate specialized cognitive adaptations.► Tool use may have evolved with enhanced cognitive abilities. ► Woodpecker finches did not outperform their nontool-using relatives in physical tasks. ► Nontool-using small tree finches made fewer errors and needed fewer trials in these tasks. ► Woodpecker finches were only better in an operant task that required perseverance. ► No indication that tool use evolved with enhanced cognitive abilities in this species.

… nature of gesture (eds G. Stam & M. …, Jan 1, 2011

Any study of communicative gesture must identify which movements are purposeful (intentionality) ... more Any study of communicative gesture must identify which movements are purposeful (intentionality) and which examples of movements should be grouped into a single gesture (granularity). Where researchers studying human gesture are aided by linguistic context, researchers studying nonhuman primates must rely on their subjects&amp;#x27; movements alone to address these questions. We propose an approach to intentionality and granularity in nonhuman primate gesture based first on the possibility that only some, but not all ...

Proceedings of the …, Jan 1, 2010

While most human language is expressed verbally, the gestures produced concurrent to speech provi... more While most human language is expressed verbally, the gestures produced concurrent to speech provide additional information, help listeners interpret meaning, and provide insight into the cognitive processes of the speaker. Several theories have suggested that gesture played an important, possibly central, role in the evolution of language. Great apes have been shown to use gestures flexibly in different situations and to modify their gestures in response to changing contexts. However, it has not previously been determined whether ...

Animal Cognition, Jan 1, 2010

Great ape gesture has become a research topic of intense interest, because its intentionality and... more Great ape gesture has become a research topic of intense interest, because its intentionality and flexibility suggest strong parallels to human communication. Yet the fundamental question of whether an animal species’ gestures carry specific meanings has hardly been addressed. We set out a systematic approach to studying intentional meaning in the gestural communication of non-humans and apply it to a sample of orangutan gestures. We propose that analysis of meaning should be limited to gestures for which (1) there is strong evidence for intentional production and (2) the recipient’s final reaction matches the presumed goal of the signaller, as determined independently. This produces a set of “successful” instances of gesture use, which we describe as having goal–outcome matches. In this study, 28 orangutans in three European zoos were observed for 9 months. We distinguished 64 gestures on structural grounds, 40 of which had frequent goal–outcome matches and could therefore be analysed for meaning. These 40 gestures were used predictably to achieve one of 6 social goals: to initiate an affiliative interaction (contact, grooming, or play), request objects, share objects, instigate co-locomotion, cause the partner to move back, or stop an action. Twenty-nine of these gestures were used consistently with a single meaning. We tested our analysis of gesture meaning by examining what gesturers did when the response to their gesture did not match the gesture’s meaning. Subsequent actions of the gesturer were consistent with our assignments of meaning to gestures. We suggest that, despite their contextual flexibility, orangutan gestures are made with the expectation of specific behavioural responses and thus have intentional meanings as well as functional consequences.

Current Biology, Jan 1, 2007

When people are not fully understood, they persist with attempts to communicate, elaborating thei... more When people are not fully understood, they persist with attempts to communicate, elaborating their speech in order to better convey their meaning [1]. We investigated whether captive orangutans (Pongo pygmaeus and Pongo abelii) would use analogous communicative strategies in signaling to a human experimenter, and whether they could distinguish different degrees of misunderstanding. Orangutans' behavior varied according to how well they had apparently been understood. When their aims were not met, they persisted in communicative attempts. However, when the interlocutor appeared partially to understand their meaning, orangutans narrowed down their range of signals, focusing on gestures already used and repeating them frequently. In contrast, when completely misunderstood, orangutans elaborated their range of gestures, avoiding repetition of failed signals. It is therefore possible, from communicative signals alone, to determine how well an orangutan's intended goal has been met. This differentiation might function under natural conditions to allow an orangutan's intended goals to be understood more efficiently. In the absence of conventional labels, communicating the fact that an intention has been somewhat misunderstood is an important way to establish shared meaning.