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M D Hauser

Publications and source records attributed to M D Hauser.

18 recordsLinked to original sources
PubMed2000

Spontaneous number representation in semi-free-ranging rhesus monkeys.

Previous research has shown that animals possess considerable numerical abilities. However, this work was based on experiments involving extensive training, a small number of captive subjects and relatively artificial testing procedures. We present the results of experiments on over 200 semi-free-ranging rhesus monkeys using a task which involves no training and mimics a natural foraging problem. The subjects observed two experimenters place pieces of apple, one at a time, into each of two opaque containers. The experimenters then walked away so that the subjects could approach. The monkeys chose the container with the greater number of apple slices when the comparisons were one versus two, two versus three, three versus four and three versus five slices. They failed at four versus five, four versus six, four versus eight and three versus eight slices. Controls established that it was the representation of number which underlay their successful choices rather than the amount of time spent placing apple pieces into the box or the volume of apple placed in the box. The failures at values greater than three slices stand in striking contrast to other animal studies where training was involved and in which far superior numerical abilities were demonstrated. The range of success achieved by rhesus monkeys in this spontaneous-number task matches the range achieved by human infants and corresponds to the range encoded in the syntax of natural languages.

Animals↗
PubMed2000

Language discrimination by human newborns and by cotton-top tamarin monkeys.

Humans, but no other animal, make meaningful use of spoken language. What is unclear, however, is whether this capacity depends on a unique constellation of perceptual and neurobiological mechanisms or whether a subset of such mechanisms is shared with other organisms. To explore this problem, parallel experiments were conducted on human newborns and cotton-top tamarin monkeys to assess their ability to discriminate unfamiliar languages. A habituation-dishabituation procedure was used to show that human newborns and tamarins can discriminate sentences from Dutch and Japanese but not if the sentences are played backward. Moreover, the cues for discrimination are not present in backward speech. This suggests that the human newborns' tuning to certain properties of speech relies on general processes of the primate auditory system.

Animals↗
PubMed1999

Perseveration, inhibition and the prefrontal cortex: a new look.

Perseverative actions are often the result of inhibitory problems; however, inhibitory problems do not always lead to perseverative actions. Some problems of inhibition have been attributed to immaturity of, or severe damage to, the prefrontal cortex. Research in this area has generally failed both to take into account species differences in prefrontal function that lead to different perseverative errors and to distinguish between perseverative errors that arise from a failure to inhibit salient emotions or motivational drives and errors that arise from an inability to engage in conceptual change. Recent studies on humans, chimpanzees, rhesus macaques, Japanese macaques, cotton-top tamarins and marmosets support this notion.

Affective Symptoms↗
PubMed1997

Tinkering with minds from the past.

Cognitive scientists argue that in the absence of language, non-human animal conceptual representations are either impoverished or completely absent. One might make comparable claims about human infants, who enter the world with different conceptual representations from adults. Nonetheless, we often treat human infants like miniature adults. This is a mistake. I argue that research on human cognition, and in particular its domain specific knowledge systems, can only succeed if it adopts a comparative perspective. To carry out this agenda, however, we require methods that can be used across species. Focusing on how numerical abilities evolved, I describe experiments on two non-human primates, representing different phylogenetic branches. Our experimental procedure--the preferential looking time technique--was designed to assess what prelinguistic human infants know about the physical and psychological world, but it is ideal for non-human animals, especially when one wishes to explore spontaneous cognitive capacities in the absence of training. Results reveal that up to a certain age, human infants and non-human primates are indistinguishable in terms of numerical competence. We must now focus on how language, together with other cognitive facilities, bring the human child to a level of numerical sophistication that exceeds non-human animals, and why non-human animal capacities stop where they do.

Animals↗
PubMed1997

Artifactual kinds and functional design features: what a primate understands without language.

Of several domains of knowledge, humans appear to be born with an innately structured representational system for making sense of objects, what properties individuate them, how they move in space, and what causes them to move from one location to another. They also appear to make simple conceptual cuts between artifactual kinds and living kinds. The basis for this distinction seems to be a combination of crucial functional properties, together with a teleological (i.e., historical/intentional) stance, one that asks 'What was this object designed for?'. Although non-human primates also appear to have considerable understanding of objects, and often use objects as tools, it is not clear whether they draw a distinction between artifactual and living kinds, and if so, what factors guide this distinction. As a step in addressing this problem, I present experiments on a small New World monkey, the cotton-top tamarin (Saguinus oedipus oedipus), designed to reveal their understanding of the functional properties of tools using a procedure associated with minimal training. Specifically, the experiments explored whether tamarins distinguish between relevant and irrelevant properties of a tool, and further, understand that some features can be transformed with little cost to functionality. The first experiment was a means-end task and involved using a cane-like object (a tool) to access a piece of food. In this experiment, there were always two choices: either the food was immediately accessible because it was located on the inside of the cane's hook or less readily accessible because it was located on the outside of the hook. Most of the tamarins reached criterion on this task within a few sessions, consistently picking the cane with the most accessible food. Subsequent experiments (2-4) involved property changes (i.e., its color, texture, size and shape) that had either significant or relatively insignificant effects on the tool's function. In general, the tamarins appeared tolerant of all property transformations as evidenced by the fact that they selected each object at least once. However, clear preferences also emerged suggesting that some properties had a more significant impact on the tool's functionality. Thus, in head-to-head competitions, tools with color or texture changes were selectively preferred over tools with shape or size changes. This makes sense color and texture do not effect the tool's function, whereas shape and size do. The final experiments involved both novel and familiar objects that, based on their current configuration, could readily be used as tools, in contrast with objects that required considerable manipulation to convert into a tool. Consistently, the tamarins preferred possible over convertible tools, and when two convertible tools were presented at the same time, they preferred the tool that required the fewest changes to the required motor response. Results suggest that the tamarins distinguish between relevant and irrelevant properties of a tool and this distinction is based on functionality, on having good design. This ability is especially surprising given the fact that tamarins do not naturally use tools, and infrequently come into contact with artifacts. Results are discussed in light of current theories concerning the representational foundations of natural kinds, and in particular, artifactual kinds.

Animals↗
PubMed1996

Numerical representations in primates.

Research has demonstrated that human infants and nonhuman primates have a rudimentary numerical system that enables them to count objects or events. More recently, however, studies using a preferential looking paradigm have suggested that preverbal human infants are capable of simple arithmetical operations, such as adding and subtracting a small number of visually presented objects. These findings implicate a relatively sophisticated representational system in the absence of language. To explore the evolutionary origins of this capacity, we present data from an experiment with wild rhesus monkeys (Macaca mulatta) that methodologically mirrors those conducted on human infants. Results suggest that rhesus monkeys detect additive and subtractive changes in the number of objects present in their visual field. Given the methodological and empirical similarities, it appears that nonhuman primates such as rhesus monkeys may also have access to arithmetical representations, although alternative explanations must be considered for both primate species.

Animals↗
PubMed1995

Self-recognition in primates: phylogeny and the salience of species-typical features.

Self-recognition has been explored in nonlinguistic organisms by recording whether individuals touch a dye-marked area on visually inaccessible parts of their face while looking in a mirror or inspect parts of their body while using the mirror's reflection. Only chimpanzees, gorillas, orangutans, and humans over the age of approximately 2 years consistently evidence self-directed mirror-guided behavior without experimenter training. To evaluate the inferred phylogenetic gap between hominoids and other animals, a modified dye-mark test was conducted with cotton-top tamarins (Saguinus oedipus), a New World monkey species. The white hair on the tamarins' head was color-dyed, thereby significantly altering a visually distinctive species-typical feature. Only individuals with dyed hair and prior mirror exposure touched their head while looking in the mirror. They looked longer in the mirror than controls, and some individuals used the mirror to observe visually inaccessible body parts. Prior failures to pass the mirror test may have been due to methodological problems, rather than to phylogenetic differences in the capacity for self-recognition. Specifically, an individual's sensitivity to experimentally modified parts of its body may depend crucially on the relative saliency of the modified part (e.g., face versus hair). Moreover, and in contrast to previous claims, we suggest that the mirror test may not be sufficient for assessing the concept of self or mental state attribution in nonlinguistic organisms.

Animals↗
PubMed1994

Left hemisphere dominance for processing vocalizations in adult, but not infant, rhesus monkeys: field experiments.

In humans, the left hemisphere of the brain is dominant for processing language. To assess the evolutionary origins of this neuropsychological mechanism, playback experiments were conducted on a large population of free-ranging rhesus monkeys (Macaca mulatta). Playbacks provided an equal opportunity to orient the right or left ear toward the speaker. Results revealed that 61 of 80 adult rhesus favored the right ear (left hemisphere) when vocalizations from their own repertoire were heard but favored the left ear when listening to heterospecific vocalizations. In contrast, infants less than a year old showed no perceptual asymmetry for conspecific or heterospecific calls. Thus, like humans, adult rhesus monkeys also evidence left hemisphere dominance for processing species-specific vocalizations. The emergence of such asymmetry, however, may depend on both differential maturation of the two hemispheres and experience with the species-typical vocal repertoire.

Age Factors↗
PubMed1994

The role of lip configuration in monkey vocalizations: experiments using xylocaine as a nerve block.

Human and nonhuman primates commonly alter the configuration of their lips during vocal production and thereby modify vocal tract length and shape. In nonhuman primates, however, the effects of lip configuration on call structure are unknown. This study was designed to investigate the importance of lip configuration in rhesus monkey (Macaca mulatta) vocal production by temporarily blocking lip movement with injections of xylocaine. For "coo" vocalizations, an affiliative contact call that is normally produced with protruded lips, the xylocaine treatment had no statistically significant effect on call duration or characteristics of the fundamental frequency (i.e., features associated with respiration and laryngeal function). However, the two formant frequencies (i.e., features resulting from the filtering properties of the supralaryngeal cavity) of the call were significantly effected. Specifically, formant frequencies increased, as would be expected from an individual incapable of compensating for a shortened vocal tract. In contrast to coos, xylocaine had no statistically significant effect on the acoustic structure of "noisy screams," a call given in response to being attacked by a dominant and produced with retracted lips (i.e., a shortened vocal tract). Results suggest that for some vocalizations, lip configuration may be essential for achieving the intended acoustic target, whereas for other vocalizations, it is less important.

Animals↗
PubMed1993

Rhesus monkey copulation calls: honest signals for female choice?

In a wide variety of mating systems, female choice is based on the assessment of male signals, both morphological and behavioural, presumed to correlate with fitness. A crucial problem, therefore, is for females to determine whether the signal represents an 'honest' reflection of male fitness. A dominant theoretical perspective in evolutionary biology suggests that signals are honest if and only if they are costly to produce. At present, there are relatively few empirical studies of the costs and benefits of signalling in the mating context, and this is especially the case for Primates. In this paper, I examine the possibility that copulations calls--vocalizations that often elicit aggressive competition within the mating arena--are honest signals of male quality. Observations of rhesus monkey (Macaca mulatta) mating behaviour reveal that the proportion of copulating males who call decreases as competition for oestrous females increases. Males who call during copulation are more likely to be aggressively attacked than males who are silent during copulation. However, males who give copulation calls obtain more matings than males who do not, and this is true for high- and low-ranking males. Because of the cost-benefit tradeoffs, copulation calls are interpreted as honest indicators of quality that may serve an important function in female mate choice.

Animals↗
PubMed1993

Right hemisphere dominance for the production of facial expression in monkeys.

In humans, the left side of the face (right hemisphere of the brain) is dominant in emotional expression. In rhesus monkeys, the left side of the face begins to display facial expression earlier than the right side and is more expressive. Humans perceive rhesus chimeras created by pairing the left half of the face with its mirror-reversed duplicate as more expressive than chimeras created by right-right pairings. That the right hemisphere determines facial expression, and the left hemisphere processes species-typical vocal signals, suggests that human and nonhuman primates exhibit the same pattern of brain asymmetry for communication.

Animals↗
PubMed1992

Costs of deception: cheaters are punished in rhesus monkeys (Macaca mulatta).

From a functional perspective, deception can evolve in animal populations but should be constrained by the costs associated with detection. It then follows that withholding information should be more prevalent as a form of deception than active falsification of information because of the relative difficulties associated with detecting cheaters. Empirical studies of deception have focused on the benefits of cheating but have provided no data on the costs associated with being detected as a cheater. I present results from field experiments on rhesus monkeys (Macaca mulatta) which show that individuals discovering food announce their discoveries by calling on 45% of all trials. Discoverers who failed to call, but were detected with food by other group members, received significantly more aggression than vocal discoverers. Moreover, silent female discoverers ate significantly less food than vocal females. This demonstrates that there are significant costs to withholding information. Such costs may constrain the frequency with which deception occurs in this and other populations.

Aggression↗
PubMed1992

Is there teaching in nonhuman animals?

We derive a simple operational definition of teaching that distinguishes it from other forms of social learning where there is no active participation of instructors, and then discuss the constituent parts of the definition in detail. From a functional perspective, it is argued that the instructor's sensitivity to the pupil's changing skills or knowledge, and the instructor's ability to attribute mental states to others, are not necessary conditions of teaching in nonhuman animals, as assumed by previous work, because guided instruction without these prerequisites could still be favored by natural selection. A number of cases of social interaction in several orders of mammals and birds that have been interpreted as evidence of teaching are then reviewed. These cases fall into two categories: situations where offspring are provided with opportunities to practice skills ("opportunity teaching"), and instances where the behavior of young is either encouraged or punished by adults ("coaching"). Although certain taxonomic orders appear to use one form of teaching more often than the other, this may have more to do with the quality of the current data set than with inherent species-specific constraints. We suggest several directions for future research on teaching in nonhuman animals that will lead to a more thorough understanding of this poorly documented phenomenon. We argue throughout that adherence to conventional, narrow definitions of teaching, generally derived from observations of human adult-infant interactions, has caused many related but simpler phenomena in other species to go unstudied or unrecorded, and severely limits further exploration of this topic.

Animal Population Groups↗
PubMed1992

Fundamental frequency declination is not unique to human speech: evidence from nonhuman primates.

In human speech, declination of the fundamental frequency (F0) of the voice spans coherent units of an utterance and, therefore, signals where units begin and end. A rapid final fall at the end of an utterance provides a further indication of an utterance's ending. The occurrence of declination is sufficiently widespread across languages that several investigators have suggested it as a language universal. Language universals may be universal because they are part of a species-specific specialization for language or, alternatively, they may constitute conventionalizations of natural dispositions of the vocal tract that may serve a communicative function. Evidence is offered favoring the latter account for declination and the final fall by showing that vocal productions of vervet monkeys (Cercopithecus aethiops) and rhesus macaques (Macaca mulatta) show declination, and vervets show clear evidence of a final fall. Interestingly, the fall in F0 may serve some communicative role in the vocal exchanges of vervets and rhesus, analogous to its signalling function in human language.

Acoustics↗
PubMed1992

Articulatory and social factors influence the acoustic structure of rhesus monkey vocalizations: a learned mode of production?

This report presents results that show that the acoustic structure of the "coo" vocalization of rhesus macaques (Macaca mulatta) varies between members of different matrilines. In the case examined, members of one matriline produce coos that are acoustically distinctive from all other matrilines and the difference is primarily due to spectral dampening and the presence of energy bands between the primary harmonics of the call. Perceptually, these acoustic modifications lead to what human listeners hear as a "nasal" utterance, suggesting the possibility of supralaryngeal filtering. Moreover, because nasal-sounding coos were only produced by members of one matriline, learning may be the primary cause of such intrafamilial similarities.

Animal Communication↗
PubMed1984

Old age and its behavioral manifestations: a study on two species of macaque.

Observations from two studies on the behavior of stumptail and Japanese macaques revealed that old females were generally less active and involved in fewer social interactions than young adult females. Old females typically avoided or maintained sufficient distance from others to decrease the possibility of interaction, but were neither excluded from social interactions nor out-competed in rank-related situations. The data strongly suggest that the old females selectively withdrew from social interactions and maintained their rank over younger members of the group. Three possible explanations are discussed for the differences in behavior between old and young adult macaque females. (1) Old females with older offspring are less likely to interact with others than old females with younger offspring; (2) old females obtain fewer benefits from social interaction than young adult females, and (3) older females have less energy to disburse for social interaction due to physiological deterioration. The age of the youngest offspring did not account for the decline in social interactions among old females. It was concluded that active withdrawal from social interactions on the part of old females is likely to be the result of both a decrease in the benefits obtained from sociality and an overall physiological deterioration.

Aging↗