Unwilling versus unable: infants' understanding of intentional action

Infants experienced a female adult handling them toys. Sometimes, however, the transaction failed, either because the adult was in various ways unwilling to give the toy (e.g., she teased the child with it or played with it herself) or else because she was unable to give it (e.g., she accidentally dropped it). Infants at 9, 12, and 18 months of age reacted with more impatience (e.g., reaching, looking away) when the adult was unwilling to give them the toy than when she was simply unable to give it. Six-month-olds, in contrast, showed no evidence of this differentiation. Because infants' behavioral responses were appropriately adapted to different kinds of intentional actions, and because the adult's actions sometimes produced results that did not match her goal (when having accidents or failed attempts), these findings provide especially rich evidence that infants first begin to understand goal-directed action at around 9 months of age.     

Combined antecedent variables as motivating operations within functional analyses

Functional analysis test conditions typically manipulate a single antecedent variable and an associated consequence to better isolate response-reinforcer relations. In some instances no problem behavior is observed, perhaps representing a false-negative finding. The present study evaluated one approach to assess potentially false-negative findings within functional analyses. Participants were exposed to single-antecedent functional analysis test conditions and combined-antecedent test conditions within a multielement design. Both participants engaged in problem behavior primarily during the combined-antecedent test conditions, and treatments matched to the results were effective in reducing problem behavior. Findings are discussed in terms of clinical implications of combining antecedent variables to further examine potentially false-negative functional analysis results.     

A preliminary analysis of adaptive responding under open and closed economies

In the current investigation, we evaluated the effects of open and closed economies on the adaptive behavior of 2 individuals with developmental disabilities. Across both types of economy, progressive-ratio (PR) schedules were used in which the number of responses required to obtain reinforcement increased as the session progressed. In closed-economy sessions, participants were able to obtain reinforcement only through interaction with the PR schedule requirements (i.e., more work resulted in more reinforcer access). In open-economy sessions, participants obtained reinforcers by responding on the PR schedule and were given supplemental (free) access to the reinforcers after completion of the session. In general, more responding was associated with the closed economy.     

Piagetian conservation of discrete quantities in bonobos (Pan paniscus), chimpanzees (Pan troglodytes), and orangutans (Pongo pygmaeus)

This study investigated whether physical discreteness helps apes to understand the concept of Piagetian conservation (i.e. the invariance of quantities). Subjects were four bonobos, three chimpanzees, and five orangutans. Apes were tested on their ability to conserve discrete/continuous quantities in an over-conservation procedure in which two unequal quantities of edible rewards underwent various transformations in front of subjects. Subjects were examined to determine whether they could track the larger quantity of reward after the transformation. Comparison between the two types of conservation revealed that tests with bonobos supported the discreteness hypothesis. Bonobos, but neither chimpanzees nor orangutans, performed significantly better with discrete quantities than with continuous ones. The results suggest that at least bonobos could benefit from the discreteness of stimuli in their acquisition of conservation skills.     

Comparing the teaching interaction procedure to social stories for people with autism

This study compared social stories and the teaching interaction procedure to teach social skills to 6 children and adolescents with an autism spectrum disorder. Researchers taught 18 social skills with social stories and 18 social skills with the teaching interaction procedure within a parallel treatment design. The teaching interaction procedure resulted in mastery of all 18 skills across the 6 participants. Social stories, in the same amount of teaching sessions, resulted in mastery of 4 of the 18 social skills across the 6 participants. Participants also displayed more generalization of social skills taught with the teaching interaction procedure to known adults and peers.     

How does cognition evolve? Phylogenetic comparative psychology

Now more than ever animal studies have the potential to test hypotheses regarding how cognition evolves. Comparative psychologists have developed new techniques to probe the cognitive mechanisms underlying animal behavior, and they have become increasingly skillful at adapting methodologies to test multiple species. Meanwhile, evolutionary biologists have generated quantitative approaches to investigate the phylogenetic distribution and function of phenotypic traits, including cognition. In particular, phylogenetic methods can quantitatively (1) test whether specific cognitive abilities are correlated with life history (e.g., lifespan), morphology (e.g., brain size), or socio-ecological variables (e.g., social system), (2) measure how strongly phylogenetic relatedness predicts the distribution of cognitive skills across species, and (3) estimate the ancestral state of a given cognitive trait using measures of cognitive performance from extant species. Phylogenetic methods can also be used to guide the selection of species comparisons that offer the strongest tests of a priori predictions of cognitive evolutionary hypotheses (i.e., phylogenetic targeting). Here, we explain how an integration of comparative psychology and evolutionary biology will answer a host of questions regarding the phylogenetic distribution and history of cognitive traits, as well as the evolutionary processes that drove their evolution.     

Are monkeys able to plan for future exchange?

Whether or not non-human animals can plan for the future is a hotly debated issue. We investigate this question further and use a planning-to-exchange task to study future planning in the cooperative domain in two species of monkeys: the brown capuchin (Cebus apella) and the Tonkean macaque (Macaca tonkeana). The rationale required subjects to plan for a future opportunity to exchange tokens for food by collecting tokens several minutes in advance. Subjects who successfully planned for the exchange task were expected to select suitable tokens during a collection period (5/10?min), save them for a fixed period of time (20/30?min), then take them into an adjacent compartment and exchange them for food with an experimenter. Monkeys mostly failed to transport tokens when entering the testing compartment; hence, they do not seem able to plan for a future exchange with a human partner. Three subjects did however manage to solve the task several times, albeit at very low rates. They brought the correct version of three possible token types, but rarely transported more than one suitable token at a time. Given that the frequency of token manipulation predicted transport, success might have occurred by chance. This was not the case, however, since in most cases subjects were not already holding the token in their hands before they entered the testing compartment. Instead, these results may reflect subjects' strengths and weaknesses in their time-related comprehension of the task.     

Great apes infer others’ goals based on context

In previous studies claiming to demonstrate that great apes understand the goals of others, the apes could potentially have been using subtle behavioral cues present during the test to succeed. In the current studies, we ruled out the use of such cues by making the behavior of the experimenter identical in the test phase of both the experimental and control conditions; the only difference was the preceding “context.” In the first study, apes interpreted a human’s ambiguous action as having the underlying goal of opening a box, or not, based on that human’s previous actions with similar boxes. In the second study, chimpanzees learned that when a human stood up she was going to go get food for them, but when a novel, unexpected event happened, they changed their expectation—presumably based on their understanding that this new event led the human to change her goal. These studies suggest that great apes do not need concurrent behavioral cues to infer others’ goals, but can do so from a variety of different types of cues—even cues displaced in time.     

The Effect of Plausible Versus Implausible Balance Scale Feedback on the Expectancies of 3- to 4-Year-Old Children

Previous studies (Case, 1985 Case , R. ( 1985 ). Intellectual development: Birth to adulthood . New York , NY : Academic . [Google Scholar]; Siegler, 1981 Siegler , R. S. ( 1981 ). Developmental sequences within and between concepts . Monographs of the Society for Research in Child Development , 46 , 1 – 84 . [Google Scholar]) have shown that children under the age of 5 years have little understanding of balance scales when required to encode the influence of weight or distance from the fulcrum. More recently, however, Halford, Andrews, Dalton, Boag, and Zielinski (2002 Halford , G. S. , Andrews , G. , Dalton , C. , Boag , C. , & Zielinski , T. ( 2002 ). Young children's performance on the balance scale: The influence of relational complexity . Journal of Experimental Child Psychology , 81 , 417 – 445 .[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) noted that an understanding based on weight alone is present even in 2-year-olds. In all these experiments, weight was varied using multiple objects of the same weight. Consequently, the children's decisions could have been based upon visual features (size, number) without necessarily taking the weight into account. The present study investigated whether young children are able to correctly encode the relevance of weight in influencing the behavior of a balance scale. We studied how well 3- to 4-year-old children learn to use one of two different weights (of equal appearance) to tip the scale. In the plausible condition, the heavy weight produced the desired outcome. In the implausible condition, the light weight caused the scale to tip. Only 4-year-olds' performance differed between conditions by learning more effectively in the plausible than the implausible condition. Our results suggest that children younger than 4 years of age have not yet developed clear expectations of the role of weights on the movements of a balance scale.     

Chimpanzee social cognition

In the late 1970s, Premack and Woodruff asked whether chimpanzees had a theory of mind. The answer to this question has remained elusive. Whereas some authors argue that chimpanzees are capable of mental state attribution, others maintain that they simply learn certain cues in ertain situations. Recent studies challenge both views. On the one hand, chimpanzees know much more about seeing than cue-based explanations suggest; on the other hand, this knowledge does not necessarily entail understanding of the mental states of others. The hypothesis I put forward here is that chimpanzees learn cues in social situations but that they are also capable of knowledge abstraction to solve novel problems.