How young children and chimpanzees (Pan troglodytes) perceive objects in a 2D display: putting an assumption to the test

Object recognition research is typically conducted using 2D stimuli in lieu of 3D objects. This study investigated the amount and complexity of knowledge gained from 2D stimuli in adult chimpanzees (Pan troglodytes) and young children (aged 3 and 4 years) using a titrated series of cross-dimensional search tasks. Results indicate that 3-year-old children utilize a response rule guided by local features to solve cross-dimensional tasks. Four-year-old toddlers and adult chimpanzees use information about object form and compositional structure from a 2D image to guide their search in three dimensions. Findings have specific implications to research conducted in object recognition/perception and broad relevance to all areas of research and daily living that incorporate 2D displays.     

Exploitation of pointing as a referential gesture in young children, but not adolescent chimpanzees

The ability of adolescent chimpanzees and 2- and 3-year-old children to use pointing gestures to locate hidden surprises was examined in two experiments. The results revealed that although young 2-year-old children appeared to have no difficulty extracting referential information from a pointing gesture (independent of gaze or distance cues) and spontaneously using it to search in specific locations, adolescent chimpanzees appeared to rely on cueconfiguration and distance-based rules. Thus, although these chimpanzees were trained to respond appropriately to the pointing gestures of a human by searching in a particular location, this ability did not easily generalize to situations in which the distance between the pointing hand and the location were more distal. Furthermore, even those chimpanzees that were able to generalize in this fashion appeared to use distance-based cues, not ones based on an appreciation of the internal attentional focus or mental referent of the experimenter as indicated by his pointing gesture.     

Object permanence in orangutans (Pongo pygmaeus), chimpanzees (Pan troglodytes), and children (Homo sapiens).

Juvenile and adult orangutans (n = 5; Pongo pygmaeus), chimpanzees (n = 7; Pan troglodytes), and 19- and 26-month-old children (n = 24; Homo sapiens) received visible and invisible displacements. Three containers were presented forming a straight line, and a small box was used to displace a reward under them. Subjects received 3 types of displacement: single (the box visited 1 container), double adjacent (the box visited 2 contiguous containers), and double nonadjacent (the box visited 2 noncontiguous containers). All species performed at comparable levels, solving all problems except the invisible nonadjacent displacements. Visible displacements were easier than invisible, and single were easier than double displacements. In a 2nd experiment, subjects saw the baiting of either 2 adjacent or 2 nonadjacent containers with no displacements. All species selected the empty container more often when the baited containers were nonadjacent than when they were adjacent. It is hypothesized that a response bias and inhibition problem were responsible for the poor performance in nonadjacent displacements.     

Getting a clear picture: young children's understanding of a televised image

Previous research has established that very young children, unlike older people, often have difficulty using a televised image as a source of information about a real event. After watching on a live video monitor as an adult in the next room hid a toy, 2‐year‐olds usually did not find it, but after watching directly through a window, children of this age succeeded. In the first experiment reported here, 2‐year‐olds could see hiding events directly and on a video monitor at the same time. This video–reality training did not improve performance on subsequent standard trials with video as the only source of information. In a second experiment, an adult demonstrated correct search behavior using video, finding a toy as the child watched on the video monitor. Despite this training and assistance, most of the children did not appear to recognize the connection between a video image and reality.     

Scale-model comprehension by chimpanzees (Pan troglodytes)

The ability of chimpanzees (Pan troglodytes) to recognize the correspondence between a scale model and its real-world referent was examined. In Experiments 1 and 2, an adult female and a young adult male watched as an experimenter hid a miniature model food in 1 of 4 sites in a scale model. Then, the chimpanzees were given the opportunity to find the real food item that had been hidden in the analogous location in the real room. The female performed significantly above chance, whereas the male performed at chance level. Experiments 3 and 4 tested 5 adult and 2 adolescent chimpanzees in a similar paradigm, using a scale model of the chimpanzees' outdoor area. Results indicate that some adult chimpanzees were able to reliably demonstrate an understanding of the relationship between a scale model and the larger space it represented, whereas other subjects were constrained by inefficient and unsuccessful search patterns.     

Gravity bias in young and adult chimpanzees (Pan troglodytes): tests with a modified opaque-tubes task

Young human children at around 2 years of age fail to predict the correct location of an object when it is dropped from the top of an S-shape opaque tube. They search in the location just below the releasing point (Hood, 1995). This type of error, called a 'gravity bias', has recently been reported in dogs and monkeys. In the present study, we investigated whether young and adult chimpanzees also show such a gravity bias in a modified version of the original opaque-tube task. The original task by Hood and colleagues required the subject to search in a location after the object had fallen, while in the task reported here, subjects were required to predict the location before the object was dropped. Thus the present procedure does not involve explicit invisible displacement operations, one of the important components of the original procedure. In Experiment 1 both young (1.5-2.5-year-old) and adult chimpanzees predicted the location of falling food items below the releasing point even when crossed tubes were used. These gravity errors remained after the extensive experience of using the tubes themselves. Experiment 2 further tested adult and 4-year-old chimpanzees under the set-up in which the straight and crossed tubes were simultaneously presented. The results were the same as those in the previous test, suggesting that developmental changes and learning effect do not affect the gravity bias in chimpanzees.     

Testing for social learning in the "artificial fruit" processing of wildborn orangutans (Pongo pygmaeus), Tanjung Puting, Indonesia

Social learning about actions, objects and sequencing was investigated in a group of 14 wildborn orangutans (four adult females and ten 3- to 5-year-old juveniles). Human models showed alternative methods and sequences for dismantling an artificial fruit to groups of participants matched by gender and age. Each participant received three to six 2-min trials in which they were given access to the artificial fruit for manipulation. Independent coders, who were unaware of which method each participant had seen, gave confidence ratings and collected action frequencies from watching video recordings of the experimental trials. No significant differences were found between groups in terms of the coders' confidence ratings, the action frequencies or the sequence of manipulations. These negative results may at least partly reflect the immaturity of a large proportion of the participants. A positive correlation was found between age and the degree of matching to the method shown. Although none of the juveniles succeeded in opening the "fruit", two out of the four adults did so and they also seemed to match more closely the sequence of elements touched over successive trials. The results are compared with similar data previously collected from human children, chimpanzees, gorillas, capuchin monkeys and common marmosets. Accepted after revision: 30 July 2001 Electronic Publication     

Auditory–visual intermodal matching based on individual recognition in a chimpanzee (Pan troglodytes)

The ability to recognize familiar individuals with different sensory modalities plays an important role in animals living in complex physical and social environments. Individual recognition of familiar individuals was studied in a female chimpanzee named Pan. In previous studies, Pan learned an auditory–visual intermodal matching task (AVIM) consisting of matching vocal samples with the facial pictures of corresponding vocalizers (humans and chimpanzees). The goal of this study was to test whether Pan was able to generalize her AVIM ability to new sets of voice and face stimuli, including those of three infant chimpanzees. Experiment 1 showed that Pan performed intermodal individual recognition of familiar adult chimpanzees and humans very well. However, individual recognition of infant chimpanzees was poorer relative to recognition of adults. A transfer test with new auditory samples (Experiment 2) confirmed the difficulty in recognizing infants. A remaining question was what kind of cues were crucial for the intermodal matching. We tested the effect of visual cues (Experiment 3) by introducing new photographs representing the same chimpanzees in different visual perspectives. Results showed that only the back view was difficult to recognize, suggesting that facial cues can be critical. We also tested the effect of auditory cues (Experiment 4) by shortening the length of auditory stimuli, and results showed that 200 ms vocal segments were the limit for correct recognition. Together, these data demonstrate that auditory–visual intermodal recognition in chimpanzees might be constrained by the degree of exposure to different modalities and limited to specific visual cues and thresholds of auditory cues.     

Chimpanzees (Pan troglodytes) recognize spatial and object correspondences between a scale model and its referent

In the present study, the contributions of spatial and object features to chimpanzees' comprehension of scale models were examined. Seven chimpanzees that previously demonstrated the ability to use a scale model as an information source for the location of a hidden item were tested under conditions manipulating the feature correspondence and spatial-relational correspondence between objects in the model and an outdoor enclosure. In Experiment 1, subjects solved the task under two conditions in which one object cue (color or shape) was unavailable, but positional cues remained. Additionally, performance was above chance under a third condition in which both types of object cues, but not position cues, were available. In Experiment 2, 2 subjects solved the task under a condition in which shape and color object cues were simultaneously unavailable. The results suggest that, much like young children, chimpanzees are sensitive to both object and spatial-relational correspondences between a model and its referent.     

The “Sh-Ape Bias” in Non-Linguistic Categorization: Comparisons between Children and Other Apes

ABSTRACT

Children show a bias toward information about shape when labeling or determining category membership for novel objects. The body of work with human children suggests that the shape bias is not restricted to linguistic contexts but is highly contingent on task demands. Testing nonhumans could provide additional information about the salience of shape cues in the absence of linguistic relevance. In order to assess the salience of shape versus color using an identical task in children and apes, we presented two adult zoo-housed chimpanzees (Pan troglodytes) and 56 three–five-year-old children with a relational matching task in which samples and comparison stimuli matched on either shape or color. Whereas children of all ages performed above chance on the task, chimpanzees performed at close to chance levels overall. However, closer inspection revealed that, whereas children performed better on shape (86%) versus color trials (78.5%), chimpanzees showed the opposite pattern, performing at chance on shape trials (49%) and above chance on color trials (72%). Children also made quicker responses on shape versus color trials, whereas chimpanzees showed the opposite pattern. Whereas shape is a highly salient cue for Western children, color may be a more salient natural cue in nonhuman primates’ natural environments. Thus, the shape bias does not appear to be an evolutionarily ancient bias when assigning category membership.     

Correlates of adult and child perceptions of social competency

In this study, the relationship between two commonly used measures of social competency, peer ratings of perceived status and adult ratings of assertiveness, were examined. In Phase I, high and low sociometric status children were videotaped responding to a series of role-play scenes; performance on these scenes was then rated retrospectively by adults for overall assertiveness. In Phase II, a second group of children who were unfamiliar with the videotaped children observed the taped scenes and provided ratings of likability, intelligence, working together, and attractiveness. In general, results revealed that children and adults differed in their ratings of the videotaped children. Further, boys used different cues in their ratings than did girls. More specifically, the sociometric status of girls was related to perceived attractiveness, whereas the sociometric status of boys was more closely related to perceived intelligence. Such findings suggest that children and adults look for and use different cues in their judgments. Given these differences, it is concluded that child and adult ratings should not be used interchangeably in the assessment of, and evaluation of, social competency in children.Portions of this research were supported by a grant from the Virginia Department of Criminal Justice Services.     

Imitation of intentional manipulatory actions in chimpanzees (Pan troglodytes)

In this study, the authors investigated the understanding of other's actions in 5 adult chimpanzees (Pan troglodytes). A human demonstrated an attempt to open different containers. Each container required a different motor pattern to open it. Along with the container, a 2nd object was made available. After a free play period in which the chimpanzees' natural behaviors toward the objects were recorded, the authors tested the following 2 phases: The demonstrator (a) tried but failed to open and (b) opened the container successfully, with 1 of 2 alternative strategies, either using an "irrelevant tool" or by hand. The chimpanzees did not reproduce the demonstrator's motor patterns precisely but did reproduce the demonstrated strategies in both phases. These results suggest that chimpanzees anticipate the intentions of others by perceiving the directionality and causality of object(s) as available cues.     

Spatial construction skills of chimpanzees (Pan troglodytes) and young human children (Homo sapiens sapiens)

Spatial construction tasks are basic tests of visual‐spatial processing. Two studies have assessed spatial construction skills in chimpanzees (Pan troglodytes) and young children (Homo sapiens sapiens) with a block modelling task. Study 1a subjects were three young chimpanzees and five adult chimpanzees. Study 1b subjects were 30 human children belonging to five age groups (24, 30, 36, 42, 48 months). Subjects were given three model constructions to reproduce: Line, Cross‐Stack and Arch, which differed in type and number of spatial relations and dimensions, but required comparable configurational understanding. Subjects’ constructions were rated for accuracy. Our results show that: (1) chimpanzees are relatively advanced in constructing in the vertical dimension; (2) Among chimpanzees only adults make accurate copies of constructions; (3) Chimpanzees do not develop in the direction of constructing in two dimensions as human children do starting from age 30 months. The pattern of development of construction skills in chimpanzees partially diverges from that of human children and indicates that spatial analysis and spatial representation are partially different in the two species.     

Psychological needs,purpose in life,and problem video game playing among Chinese young adults

The negative impacts of excessive and problematic video game playing on both children and adults are attracting increasing concern. Based on self‐determination theory (SDT; Ryan & Deci, 2000), this study hypothesized that the three basic psychological needs of autonomy, competence, and relatedness are positively associated with purpose in life, which in turn acts as a protective factor against problem video game playing among Chinese young adult players. Through a questionnaire survey with a sample of 165 Chinese adults aged between 18 and 30 years (mean age = 22.7 years), we found that perceived autonomy, competence, relatedness, and purpose in life were all negatively correlated with problem game playing. The demographic and psychological factors explained 38% of the variances of problem game playing. Specifically, gender, perceived relatedness, and purpose in life emerged as the three most salient predictors of problem game playing among the Chinese young adults. The mediating role of purpose in life was evidenced and it was found that purpose in life mediated the influences of the psychological needs proposed by SDT on problem game playing. Moreover, young men were significantly more susceptible to problem game playing than their female counterparts. To conclude, psychological needs and purpose in life influenced Chinese young adults’ vulnerability to problem game playing directly or indirectly. Intervention programs that encourage social involvement and voluntary work, as well as counseling service that helps clients to search for life purpose, are suggested for intervening in problem game playing among Chinese young adults.     

Perception of complex geometric figures in chimpanzees (Pan troglodytes) and humans (Homo sapiens): analyses of visual similarity on the basis of choice reaction time.

In a conditional-discrimination task (matching-to-sample), we assessed similarities among figures consisting of 2 elemental figures through the choice reaction time, nonmetric multidimensional scaling, and hierarchical cluster analysis data from chimpanzees (Pan troglodytes) and humans (Homo sapiens). Humans also rated similarities among figures. The results of the 3 experiments clearly indicated that the reaction time data obtained from chimpanzees' performances were useful measures of the similarities among figures. The results suggested that chimpanzees and humans perceived the complex figures similarly. The outer-contour elements were perceived most dominantly by both species, and the straight-line elements were perceived least dominantly. Both species showed the same perceptual hierarchy or dominance among perceptual categories, as determined by the similarity of simple elements, on the basis of transformational invariances.     

Understanding communicative intentions and semiotic vehicles by children and chimpanzees

Developmental and comparative studies of the ability to understand communicative intentions using object-choice tasks raise questions concerning the semiotic properties of the communicative signals, and the roles of rearing histories, language and familiarity. We adapted a study by Tomasello, Call, and Gluckman (1997), in which a “helper” indicated the location of a hidden reward to children of three ages (18, 24, and 30 months) and to four chimpanzees, by means of one of four cues: Pointing, Marker, Picture and Replica. For the chimpanzees, we controlled for familiarity by using two helpers, one unfamiliar and one highly familiar. Even 18-months performed well on Pointing and Marker, while only the oldest group clearly succeeded with Picture and Replica. Performance did not correlate with scores for the Swedish Early Communicative Development Inventory (SECDI). While there were no positive results for the chimpanzees on the group level, and no effect of familiarity, two chimpanzees succeeded on Pointing and Marker. Results support proposals of a species difference in understanding communicative intentions, but also highlight the need to distinguish these from the complexity of semiotic vehicles and to consider both factors.     

Teaching apes to ape language: explaining the imitative and nonimitative signing of a chimpanzee (Pan troglodytes)

Fifteen videotaped conversations of a chimpanzee signing with his trainers were examined in order to determine (a) whether the ape was using imitation to learn about new language forms as some human children do and (b) whether the ape's nonimitative utterances implied knowledge of linguistic structures. The answers to both questions were negative. The evidence suggests that the utterances lacked the semantic and syntactic organization found in the utterances of most children. Instead of learning to use signs as symbols for communicating propositional messages, the ape learned to use gestures as nonsymbolic instrumental responses under the stimulus control of objects in the signing context and verbal and nonverbal cues from the trainers. Other research now underway with chimpanzees may eventually reveal whether this performance is characteristic of chimpanzees in general or is the result of particular training strategies used to teach language to chimpanzees.     

Relative numerosity discrimination by chimpanzees (Pan troglodytes): evidence for approximate numerical representations

Two adult chimpanzees were trained on a relative “numerosity” discrimination task. In each trial, two arrays containing different numbers of red dots were presented on a CRT monitor. The subjects were required to choose the array containing the larger number of dots. In Experiment 1, using numerosities between 1 and 8, 28 different pairs were presented repeatedly, and accuracy scores were analyzed to explore which cues the chimpanzee subjects utilized to perform the task. Multiple regression analyses revealed that the subjects’ performance was (1) not simply controlled by the “numerical” difference between arrays, but that it was (2) best described by Fechner’s Law–that is accuracy increased linearly with the logarithmic value of the numerical difference between arrays divided by the number in the larger of the two arrays. This relationship was maintained when using much larger numerosities (Experiment 3). In Experiment 2, the chimpanzees were tested on the effects of total area and density by manipulating dot size and presentation area. The results revealed that these factors clearly affected the subjects’ performance but that they could not alone explain the results, suggesting that the chimpanzees did use relative numerosity difference as a discriminative cue.     

Which cues are available to 24-month-olds? Evidence from point-of-gaze measures during search

In previous research 2-year-olds have failed to show knowledge of solidity in a search task in which a ball rolled behind a screen and was stopped by a barrier. The screen had four doors and the barrier was visible above the door hiding the ball. To establish what cues 2-year-olds might be using, precise point-of-gaze measures were taken during the hiding event. A transparent screen with opaque doors provided two cues: (1) the ball could be tracked until it failed to emerge, and (2) the barrier's position could indicate the correct door. Point-of-gaze measures revealed that children failed to use the more indirect cue of the barrier, which requires reasoning and spatial integration. Their search success was predicted only by the more immediate cue of actively tracking the ball. These findings support the claim that children use best those cues directly related to the object's disappearance, while failing to use cues that entail higher cognitive demands.     

Visual search by chimpanzees (Pan): assessment of controlling relations.

Three experimentally sophisticated chimpanzees (Pan), Akira, Chloe, and Ai, were trained on visual search performance using a modified multiple-alternative matching-to-sample task in which a sample stimulus was followed by the search display containing one target identical to the sample and several uniform distractors (i.e., negative comparison stimuli were identical to each other). After they acquired this task, they were tested for transfer of visual search performance to trials in which the sample was not followed by the uniform search display (odd-item search). Akira showed positive transfer of visual search performance to odd-item search even when the display size (the number of stimulus items in the search display) was small, whereas Chloe and Ai showed a transfer only when the display size was large. Chloe and Ai used some nonrelational cues such as perceptual isolation of the target among uniform distractors (so-called pop-out). In addition to the odd-item search test, various types of probe trials were presented to clarify the controlling relations in multiple-alternative matching to sample. Akira showed a decrement of accuracy as a function of the display size when the search display was nonuniform (i.e., each "distractor" stimulus was not the same), whereas Chloe and Ai showed perfect performance. Furthermore, when the sample was identical to the uniform distractors in the search display, Chloe and Ai never selected an odd-item target, but Akira selected it when the display size was large. These results indicated that Akira's behavior was controlled mainly by relational cues of target-distractor oddity, whereas an identity relation between the sample and the target strongly controlled the performance of Chloe and Ai.