Nonenculturated Orangutans' (Pongo pygmaeus) Use of Experimenter-Given Manual and Facial Cues in an Object-Choice Task.

Several experiments have been performed, to examine whether nonhuman primates are able to make use of experimenter-given manual and facial (visual) cues to direct their attention to a baited object. Contrary to the performance of prosimians and monkeys, great apes repeatedly have shown task efficiency in experiments such as these. However, many great ape subjects used have been "enculturated" individuals. In the present study, 3 nonenculturated orangutans (Pongo pygmaeus) were tested for their ability to use experimenter-given pointing, gazing, and glancing cues in an object-choice task. All subjects readily made use of the pointing gesture. However, when subjects were left with only gazing or glancing cues, their performance deteriorated markedly, and they were not able to complete the task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The performance of bonobos (Pan paniscus), chimpanzees (Pan troglodytes), and orangutans (Pongo pygmaeus) in two versions of an object-choice task.

The object-choice task tests animals’ ability to use human-given cues to find a hidden reward located in 1 of 2 (or more) containers. Great apes are generally unskillful in this task whereas other species including dogs (Canis familiaris) and goats (Capra hircus) can use human-given cues to locate the reward. However, great apes are typically positioned proximal to the containers when receiving the experimenter’s cue whereas other species are invariably positioned distally. The authors investigated how the position of the subject, the human giving the cue and the containers (and the distance among them) affected the performance of 19 captive great apes. Compared to the proximal condition, the distal condition involved larger distances and, critically, it reduced the potential ambiguity of the cues as well as the strong influence that the sight of the containers may have had when subjects received the cue. Subjects were far more successful in the distal compared to the proximal condition. The authors suggest several possibilities to account for this difference and discuss our findings in relation to previous and future object-choice research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of human visual attention cues by olive baboons (Papio anubis) in a competitive task.

The ability of 4 olive baboons (Papio anubis) to use human gaze cues during a competitive food task was investigated. Three baboons used head orientation as a cue, and 1 individual also used eye direction alone. As the baboons did not receive prior training with gestural cuts, their performance suggests that the competitive paradigm may be more appropriate for testing nonhuman primates than the standard object-choice paradigm. However, the baboons were insensitive to whether the experimenter could actually perceive the food item, and therefore the use of visual orientation cues may not be indicative of visual perspective-taking abilities. Performance was disrupted by the introduction of a screen and objects to conceal food items and by the absence of movement in cues presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of Visual, Acoustic, and Olfactory Information During Embedded Invertebrate Foraging in Brown Capuchins (Cebus apella).

Experiments were conducted to investigate which sensory cues are used by brown capuchins (Cebus apella) in embedded invertebrate foraging. The importance of visual, olfactory, and acoustic cues in such foraging was determined by presenting subjects with a stimulus log modified to block out given sensory cues. Experiment 1 was designed to investigate whether subjects could locate an invertebrate embedded in wood when only visual, acoustic, or olfactory information was available. Experiments 2 and 3 were designed to investigate extractive foraging behavior when two sensory cues were provided. It was hypothesized that the combination of visual and acoustic information would be necessary for subjects to successfully locate embedded invertebrates. Results indicated that subjects' performance was most successful when both visual and acoustic information was available. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gorillas (Gorilla gorilla) and Orangutans (Pongo pygmaeus) Encode Relevant Problem Features in a Tool-Using Task.

Two important elements in problem solving are the abilities to encode relevant task features and to combine multiple actions to achieve the goal. The authors investigated these 2 elements in a task in which gorillas (Gorilla gorilla) and orangutans (Pongo pygmaeus) had to use a tool to retrieve an out-of-reach reward. Subjects were able to select tools of an appropriate length to reach the reward even when the position of the reward and tools were not simultaneously visible. When presented with tools that were too short to retrieve the reward, subjects were more likely to refuse to use them than when tools were the appropriate length. Subjects were proficient at using tools in sequence to retrieve the reward. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Effect of Human Command Phonetic Characteristics on Auditory Cognition in Dogs (Canis familiaris).

Six dogs (Canis familiaris) were trained to sit and come reliably in response to tape-recorded commands. The phonemes within these commands were then changed, and the dogs' behavior in response to these modified commands was recorded. Performance markedly declined in all cases, with the type of alteration affecting response to the modified sit command but not to the modified come command. The results suggest that dogs do not perceive a tape-recorded command as simply a physical sound but that they recognize a relationship between certain sounds. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An obedient orangutan (Pongo abelii) performs perfectly in peripheral object-choice tasks but fails the standard centrally presented versions.

Mulcahy and Call (2009) found that bonobos (Pan paniscus) and chimpanzees (Pan troglodytes) but not orangutans (Pongo pygmaeus) perform significantly better in a peripheral version of the object-choice task compared to the original central version. Orangutans may have failed because they avoided direct eye contact with the experimenter when the cue was given. We investigated this possibility by conducting peripheral and central object choice tasks with an obedient orangutan (Pongo abelii) whom the experimenter could elicit eye contact with in each trial. In contrast to Mulcahy and Call's findings, the subject only failed the object choice task when tested with the central and not the peripheral version. We investigated whether success was because of the greater distance the subject was required to move in order to make a choice in peripheral trials. Results show that this was an unlikely factor in the subject's success. We discuss our findings in relation to previous and future object-choice research. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Verbal Attention Getting as a Key Factor in Social Learning Between Dog (Canis familiaris) and Human.

Pet dogs (Canis familiaris) learn to detour a V-shaped fence effectively from an unfamiliar human demonstrator. In this article, 4 main features of the demonstrator's behavior are highlighted: (a) the manipulation of the target, (b) the familiarity of the demonstrator, (c) the role of verbal attention-getting behavior, and (d) whether a strange trained dog could also be an effective demonstrator. The results show that the main factor of a successful human demonstration is the continuous verbal communication with the dog during detouring. It was also found that an unfamiliar dog demonstrator was as efficient as the unfamiliar experimenter. The experiments provide evidence that in adult dogs, communicative context with humans is needed for effective interspecific social learning to take place. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chimpanzees (Pan troglodytes) Are Predominantly Right-Handed: Replication in Three Populations of Apes.

Population-level right-handedness has historically been considered a hallmark of human evolution. Even though recent studies in chimpanzees (Pan troglodytes) have demonstrated population-level right-handedness for certain behaviors, some have questioned the validity and consistency of these findings by arguing that reported laterality effects are specific to certain colonies of apes and to those chimpanzees reared by humans. The authors report evidence of population-level right-handedness in 3 separate colonies of chimpanzees. Moreover, handedness in the 3 colonies was unrelated to the proportion of subjects that were raised by humans. This is the strongest evidence to date that population-level handedness is evident in chimpanzees and is not an artifact of human rearing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Asymmetries in the Hippocampus and Amygdala of Chimpanzees (Pan troglodytes).

Magnetic resonance imaging was used to measure the hippocampal and amygdalar volumes of 60 chimpanzees (Pan troglodytes). An asymmetry quotient (AQ) was then used to calculate the asymmetry for each of the structures. A one-sample t test indicated that there was a population-level right hemisphere asymmetry for the hippocampus. There was no significant population-level asymmetry for the amygdala. An analysis of variance using sex and rearing history as between-group variables showed no significant main effects or interaction effects on the AQ scores; however, males were more strongly lateralized than females. Several of these findings are consistent with results found in the human literature. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differences Between Golden Hamsters (Mesocricetus auratus) and Norway Rats (Rattus norvegicus) in Preference for the Sole Diet That They Are Eating.

D. DiBattista (2002) reported that hamsters but not rats showed reduced preferences for the sole diet they had eaten for 10 days. In the current study, the authors fed Norway rats (Rattus norvegicus) a nutritious diet for either 3 or 10 days, then tested them either immediately or 1 or 3 days later. The authors found that like golden hamsters (Mesocricetus auratus), rats exhibited reduced preferences for a prefed diet but only if tested either immediately or 1 day after prefeeding, not if tested 3 days later (when D. DiBattista tested his hamsters). Rats and hamsters differed in the longevity, not the development, of reduced preferences for a palatable food eaten for several consecutive days. Such a response might aid dietary generalists in constructing balanced diets when no single available food is nutritionally adequate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Comparative Study of the Use of Visual Communicative Signals in Interactions Between Dogs (Canis familiaris) and Humans and Cats (Felis catus) and Humans.

Dogs' (Canis familiaris) and cats' (Felis catus) interspecific communicative behavior toward humans was investigated. In Experiment 1, the ability of dogs and cats to use human pointing gestures in an object-choice task was compared using 4 types of pointing cues differing in distance between the signaled object and the end of the fingertip and in visibility duration of the given signal. Using these gestures, both dogs and cats were able to find the hidden food; there was no significant difference in their performance. In Experiment 2, the hidden food was made inaccessible to the subjects to determine whether they could indicate the place of the hidden food to a naive owner. Cats lacked some components of attention-getting behavior compared with dogs. The results suggest that individual familiarization with pointing gestures ensures high-level performance in the presence of such gestures; however, species-specific differences could cause differences in signaling toward the human. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence of a Time-Dependent Long-Term Stage of Memory for a Spatial Learning Task in the Chick (Callus gallus).

The generalizability of temporal parameters of memory formation previously observed for a passive avoidance task was investigated in a spatial task with day-old chicks (Callus gallus). The percentage improvement in completion time over 2 separate trials was measured, and chicks were found to complete the second trial faster at all times tested up to 2 hr, except at 55 min posttraining. In addition, retention at 120 min, but not at 30 min, posttraining was found to be impaired by protein synthesis inhibition. These findings are consistent with the timing of a long-term stage of memory formation following passive avoidance training, implying that there may be some hardwiring to the temporal characteristics of memory formation in this species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reorientation in a Two-Dimensional Environment: II. Do Pigeons (Columba livia) Encode the Featural and Geometric Properties of a Two-Dimensional Schematic of a Room?

Pigeons (Columba livia) searched for a hidden target area in images showing a schematic rectangular environment. The absolute position of the goal varied across trials but was constant relative to distinctive featural cues and geometric properties of the environment. Pigeons learned to use both of these properties to locate the goal. Transformation tests showed that pigeons could use either the color or shape of the features, but performance was better with color cues present. Pigeons could also use a single featural cue at an incorrect corner to distinguish between the correct corner and the geometrically equivalent corner; this indicates that they did not simply use the feature at the correct corner as a beacon. Interestingly, pigeons that were trained with features spontaneously encoded geometry. The encoded geometric information withstood vertical translations but not orientation transformations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Following and Joining the Informed Individual in Semifree-Ranging Tonkean Macaques (Macaca tonkeana).

The authors investigated whether Tonkean macaques (Macaca tonkeana) can distinguish between 2 group mates with different knowledge and improve their foraging performance. The subjects were 8 young individuals belonging to a group raised in a 2-acre park. The authors carried out 192 tests in which subgroups of 3 individuals were released in a food search situation. Two leaders could be informed about 2 different food sites. A naive follower could choose to follow 1 leader or another. The follower could find the correct site when 1 leader was informed about food location. There was no evidence that the follower identified the best leader, however. The less well-informed leader generally joined the other leader, prompting the follower to follow them. The followers' pathways were mainly determined by the interactions of leaders. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sexual Dimorphism and the NMDA Receptor in Alloparental Behavior in Juvenile Prairie Voles (Microtus ochrogaster).

The prairie vole (Microtus ochrogaster) exhibits parental behavior in both males and females and extensive alloparenting in juveniles. The authors studied the effects on juvenile alloparenting of antagonists for the PCP, glycine, and glutamate sites on the N-methyl-D-aspartate (NMDA) receptor. In male voles, all 3 drugs had an inverted-U dose-response curve. This change could not be attributed to fear of the pup or a nonspecific impairment of cognition, level of locomotor activity, or motor coordination. The PCP site antagonist had a U-shaped dose-response curve in females, the opposite of that in males, but neither of the other drugs changed female alloparental behavior. Both male and female voles exhibit alloparental behavior, but its neurobiological underpinnings are sexually dimorphic in juveniles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibitory Control and Response Selection in Problem Solving: How Cotton-Top Tamarins (Saguinus oedipus) Overcome a Bias for Selecting the Larger Quantity of Food.

When presented with a choice between 1 and 3 pieces of food in a type of reversed contingency task, 4 cotton-top tamarins (Saguinus oedipus) consistently chose the 3 pieces of food and received nothing, even though the choice of 1 piece would have yielded 3. However, in a task in which the tamarins received the 1 piece of food when they chose it, all subjects learned to select 1 over 3. Thus, the tamarins' prior failure on the reversed contingency task did not result entirely from an inherent inability to suppress the prepotent response of reaching to the larger of 2 quantities of food. After the experience of selecting the smaller quantity and receiving it, all of the tamarins solved the version of the reversed contingency task that they failed initially. These results suggest that the tamarins' initial failure may have reflected a difficulty with selecting an alternative response option. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex, Age, and Training Modulate Spatial Memory in the Rhesus Monkey (Macaca mulatta).

The authors tested 90 rhesus monkeys (Macaca mulatta) on a task of spatial memory, the spatial Delayed Recognition Span Test. The results showed that performance declined significantly with age, males had greater scores than females, and the rate of apparent decline with age was greater in males than in females. Both working and reference memory declined with age, but only working memory showed sex differences. The authors compared these data with that of 22 monkeys who were trained on a simpler version of the task before formal testing. Training had no effect on males but dramatically improved working memory in young females. The results confirm a male advantage in spatial working memory at a young age and confirm a greater decline with age in males than in females. It is important to note that prior training completely reverses the deficits of young females. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial Ability and Home-Range Size: Examining the Relationship in Western Men and Women (Homo sapiens).

In mammals, spatial sex differences may have coevolved with sex differences in the size of home ranges. This study first evaluated whether, in keeping with most mammals and traditional human (Homo sapiens) societies, home ranges are larger in male than in female Westerners. Second, it established whether navigation patterns are associated with a broader set of spatial abilities in men than in women. Results showed that current male home ranges surpass female home ranges. Ranging was also positively correlated with achievement in tests of mental rotation, surface development, and location memory among men only, whereas it was associated with embedded figures scores in both sexes. Overall, these findings substantiate the adaptive role of several spatial sex differences in humans. (PsycINFO Database Record (c) 2010 APA, all rights reserved)