David Premack

Does the chimpanzee have a theory of mind

An individual has a theory of mind if he imputes mental states to himself and others. A system of inferences of this kind is properly viewed as a theory because such states are not directly observable, and the system can be used to make predictions about the behavior of others. As to the mental states the chimpanzee may infer, consider those inferred by our own species, for example, purpose or intention, as well as knowledge, belief, thinking, doubt, guessing, pretending, liking, and so forth. To determine whether or not the chimpanzee infers states of this kind, we showed an adult chimpanzee a series of videotaped scenes of a human actor struggling with a variety of problems. Some problems were simple, involving inaccessible food – bananas vertically or horizontally out of reach, behind a box, and so forth – as in the original Kohler problems; others were more complex, involving an actor unable to extricate himself from a locked cage, shivering because of a malfunctioning heater, or unable to play a phonograph because it was unplugged. With each videotape the chimpanzee was given several photographs, one a solution to the problem, such as a stick for the inaccessible bananas, a key for the locked up actor, a lit wick for the malfunctioning heater. The chimpanzees consistent choice of the correct photographs can be understood by assuming that the animal recognized the videotape as representing a problem, understood the actors purpose, and chose alternatives compatible with that purpose.

Intentional communication in the chimpanzee: The development of deception

Abstract Communication about the location of a hidden incentive was studied in chimpanzee-human dyads, in which each member of a pair served alternately as “sender” and “recipient” of information. When the human cooperated with the chimpanzee in finding the goal, from the very beginning the chimpanzees were able to produce and comprehend behavioral cues which conveyed accurate locational information. When the human and chimpanzee competed for the goal, the chimpanzees learned both to withhold information or mislead the recipient, and to discount or controvert the senders own misleading cues. The chimpanzees ability to convey and utilize both accurate and misleading information, by taking into account the nature of the sender or recipient, provides evidence of a capacity for intentional communication in this nonhuman primate species.

“Gavagai!” or the future history of the animal language controversy☆

Abstract In placing the attempts to teach language to nonhuman species in both a cultural and philosophical context, we consider evolutionary claims about the origins of human language, and Quines indeterminacy of translation thesis. In contrasting the natural language acquired by humans with the artificial language taught nonhumans, we propose treating the human mind as a blend of learning, hard-wiring and cognition. We discuss the nature of each of the components, suggest how they may interact, and compare the three-component human system with the two-component system of other species.

Do Infants Have a Sense of Fairness

Two experiments examined infants’ expectations about how an experimenter should distribute resources and rewards to other individuals. In Experiment 1, 19-month-olds expected an experimenter to divide two items equally, as opposed to unequally, between two individuals. The infants held no particular expectation when the individuals were replaced with inanimate objects, or when the experimenter simply removed covers in front of the individuals to reveal the items (instead of distributing them). In Experiment 2, 21-month-olds expected an experimenter to give a reward to each of two individuals when both had worked to complete an assigned chore, but not when one of the individuals had done all the work while the other played. The infants held this expectation only when the experimenter could determine through visual inspection who had worked and who had not. Together, these results provide converging evidence that infants in the 2nd year of life already possess context-sensitive expectations relevant to fairness.

Human and animal cognition: Continuity and discontinuity

Microscopic study of the human brain has revealed neural structures, enhanced wiring, and forms of connectivity among nerve cells not found in any animal, challenging the view that the human brain is simply an enlarged chimpanzee brain. On the other hand, cognitive studies have found animals to have abilities once thought unique to the human. This suggests a disparity between brain and mind. The suggestion is misleading. Cognitive research has not kept pace with neural research. Neural findings are based on microscopic study of the brain and are primarily cellular. Because cognition cannot be studied microscopically, we need to refine the study of cognition by using a different approach. In examining claims of similarity between animals and humans, one must ask: What are the dissimilarities? This approach prevents confusing similarity with equivalence. We follow this approach in examining eight cognitive cases—teaching, short-term memory, causal reasoning, planning, deception, transitive inference, theory of mind, and language—and find, in all cases, that similarities between animal and human abilities are small, dissimilarities large. There is no disparity between brain and mind.

Artificial language training in global aphasics.

Abstract Natural language assessment and artificial language training were undertaken in seven globally aphasic patients sustaining left hemisphere damage. Initial assessment of natural language showed some semantic knowledge but no syntactic or grammatical ability. Words were distinguished fron nonwords and words were spelled in the absence of semantic comprehension. These results are consistent with a prelinguistic coding of verbal stimuli as visual gnostic units. Despite gross deficits in natural language, these patients were able to learn an artificial language system using cut-out paper symbols for words. Various levels of competence were attained ranging from the expression of relations between objects (same-different) to simple statements of action (subject-predicate-direct object). Other tests of conceptual-cognitive capacity revealed potential for abstraction and conceptual thought. It is proposed that despite massive language loss, globally aphasic patients retain a rich conceptual system and at least some capacity for symbolization and primitive linguistic functions.

Spontaneous transfer of matching by infant chimpanzees (Pan troglodytes).

Four infant chimpanzees learned a matching-to-sample task when only two training stimuli were used. They then spontaneously transferred the matching concept to novel items, including three-dimensional objects and fabric swatches, without any experimenter-provided differential feedback. These results support the view that the matching concept is broadly construed by chimpanzees from the beginning and does not depend upon explicit training.

Infants attribute value± to the goal-directed actions of self-propelled objects

Motion is a fundamental source of information for basic human interpretations; it is basic to the fundamental concept of causality and, the present model argues, equally basic to the fundamental concept of intentionality. The model is based on two main assumptions: When an infant perceives an object (1) moving spontaneously and (2) displaying goaldirected action, it will interpret the object as intentional and assign to it the unique properties of the psychological domain. The key property tested was: Do infants attribute value to interactions between intentional objects using criteria specified by the model? We showed infants (average age 52 weeks) computer-generated animations of spontaneously moving balls, using looking time in a standard habituation/dishabituation paradigm. In two positive interactions, one ball either caressed another, or helped it achieve its goal; whereas in two negative interactions, one ball either hit another, or prevented it from achieving its goal. In keeping with predictions of the model, when transferred to a negative condition, infants who had been habituated on a positive condition showed greater dishabituation than those habituated on a negative condition. The results could not be easily explained by the similarity relations among the animations depicting the interactions. The results suggest that well before the age when the child can ascribe mental states or has a theory of mind, it recognizes the goals of self-propelled objects and attributes value to the interactions between them.

Children's comprehension and memory for stories☆

Abstract Sixteen 4-year-olds and sixteen 6-year-olds were shown four picture stories consisting of 15 to 18 pictures without text. The stories were well structured, consisting of two or more causally and temporally related episodes. The children were asked to describe each picture, and, after seeing all the pictures of a story, to recall the story without pictures. The pictures were either presented in their normal order or in scrambled order. The data analysis concentrated upon the comparison between the responses in the normal condition when the children were telling a story and in the scrambled condition, when they were merely responding to the pictures as such without the story context. The results showed that even the 4-year-olds, but especially the older children, were interpreting the pictures as stories in the normal condition and that their knowledge about stories, i.e., the story schema, determined the nature of their responses. Even in the scrambled condition the 6-year-olds tried to make sense of the pictures in terms of a story by making inferences, attributing thoughts and emotions to the characters, and using narrative conventions, while the 4-year-olds often reverted to a simple labeling strategy. In recall all of these trends were emphasized. Those parts of the descriptions that were best integrated into a story were recalled best, while nonintegrated descriptions tended to be forgotten.

Positive Contrast in the Runway Obtained with Delay of Reward

The failure to find positive contrast effects in the runway may be attributed to a ceiling effect that can be overcome with the use of delay of reward. Rats were trained one trial a day in a runway with small, medium, or large reward. When a shift to large reward was combined with delay of reward, shift groups slowed down less than controls.