Multiple measures of motor lateralization in human primates (Homo sapiens).

Laterality was assessed in 100 human (Homo sapiens) subjects through the use of five measures of motoric behavior in three categories: locomotor, manual, postural. Locomotor meaures included leading limb for initiation of walking and whole-body turning. Performance and questionnaire measures were used to assess lateral hand bias. Postural bias was assessed as the weight distribution in quiet standing. Population-level biases on the manual and leading limb measures were to the right; on posture and turning, to the left. Locomotor measure were found to be altered by marching experience. Only the manual measures were correlated. We compare the results with those of nonhuman primate studies (e.g., C. Forsythe et al, see PA, Vol 76:477, G. W. Milliken et al, see PA, Vol 77:9169) that have used similar measures and discuss some patterns of laterality common to human and nonhuman primates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Global and local processing in adult humans (Homo sapiens), 5-year-old children (Homo sapiens), and adult cotton-top tamarins (Saguinus oedipus).

This study compared adults (Homo sapiens), young children (Homo sapiens), and adult tamarins (Saguinus oedipus) while they discriminated global and local properties of stimuli. Subjects were trained to discriminate a circle made of circle elements from a square made of square elements and were tested with circles made of squares and squares made of circles. Adult humans showed a global bias in testing that was unaffected by the density of the elements in the stimuli. Children showed a global bias with dense displays but discriminated by both local and global properties with sparse displays. Adult tamarins' biases matched those of the children. The striking similarity between the perceptual processing of adult monkeys and humans diagnosed with autism and the difference between this and normatively developing human perception is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Grunt communication in human infants (Homo sapiens).

Laryngeally produced vocalizations termed grunts function communicatively in many species. The vocalizations and accompanying behavior of 5 human infants videorecorded monthly at the transition to speech were analyzed to determine the frequency, physiological basis, and functional status of grunt production, a phenomenon systematically studied for the first time here. Earliest grunts occurred accompanying movement or effort; next, they accompanied acts of focal attention; and finally they were used in communication. Communicative use was followed by the onset of referential ability in language. This sequence is interpreted in relation to the physiological basis of these vocalizations in respiratory function and to additional developmental variables observed in the children. The findings have implications for the transition to the communicative repertoire in other species in which laryngeal function contributes to communication. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stages of category learning in monkeys (Macaca mulatta) and humans (Homo sapiens).

Smith and Minda (1998) and Blair and Homa (2001) studied the time course of category learning in humans. They distinguished an early, abstraction-based stage of category learning from a later stage that incorporated a capacity for categorizing exceptional category members. The present authors asked whether similar processing stages characterize the category learning of nonhuman primates. Humans (Homo sapiens) and monkeys (Macaca mulatta) participated in category-learning tasks that extended Blair and Homa’s paradigm comparatively. Early in learning, both species improved on typical items more than on exception items, indicating an initial mastery of the categories’ general structure. Later in learning, both species selectively improved their exception-item performance, indicating exception-item resolution or exemplar memorization. An initial stage of abstraction-based category learning may characterize categorization across a substantial range of the order Primates. This default strategy may have an adaptive resonance with the family resemblance organization of many natural-kind categories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discrimination of duration ratios by pigeons (Columba livia) and humans (Homo sapiens).

Humans were trained on 2 versions of a 2-alternative, forced-choice procedure. First, Ss judged which of 2 successive stimulus durations was longer. Second, Ss judged whether the ratio of the 2 durations was less or greater than a criterion ratio (e.g., 2:1). Accuracy was significantly lower for the task in which the judgment was made according to the ratio of the 2 durations. This result is different than that obtained by J. G. Fetterman et al (1989), who trained pigeons on a similar pair of tasks and found that pigeons' performance was comparable for the 2 discriminations. Comparisons of the pigeon and human data suggest that humans were more accurate than pigeons when the judgment involved which duration was longer, but that accuracy was comparable for the ratio-based task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Flexible serial response learning by pigeons (Columba livia) and humans (Homo sapiens).

Experimental tasks designed to involve procedural memory are often rigid and unchanging, despite many reasons to expect that implicit learning processes can be flexible and support considerable variability. A version of the serial response time (SRT) task was developed, in which the locations of targets were probabilistically determined. Targets appeared in locations according to both a structured sequence and a cue validity parameter, and the time to respond to each target was measured. Pigeons (Columba livia) and humans (Homo sapiens) both showed response time facilitation at the highest tested value for cue validity, and the magnitude of that facilitation gradually weakened as cue validity was decreased. Both species showed evidence that response times were largely determined by the local predictabilities of individual cue locations. In addition, humans showed some evidence that explicit knowledge of the sequence affected response times, specifically when cue validity was 100%. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Delayed figure reconstruction by a chimpanzee (Pan troglodytes) and humans (Homo sapiens).

A chimpanzee (Pan troglodytes) was trained to construct a copy of 3-element compound figures from a set of 9 elements. Delay intervals between sample offset and element presentation varied. The chimpanzee maintained accuracy at about 80% correct for a delay of 32 s, which was slightly higher than the mean of 4 human (Homo sapiens) Ss. Excellent visual reproductive memory in the chimpanzee as compared with that in humans was demonstrated. However, the nature of the reproductive memory was different in the 2 species in that humans better constructed meaningful figures, which represented food items, than meaningless ones, whereas the chimpanzee constructed these 2 types of figures with the same accuracy. This outcome suggests that the reproductive memory for meaningful figures of the chimpanzee may have been processed separately from symbolic processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Orientation invariant pattern recognition by pigeons (Columba livia) and humans (Homo sapiens).

The orientation invariance of visual pattern recognition in pigeons and humans was studied using a conditioned matching-to-sample procedure. A rotation effect, a lengthening of choice latencies with increasing angular disparities between sample and comparison stimuli, was replicated with humans. The choice speed and accuracy of pigeons was not affected by orientation disparities. Novel mirror-image stimuli, rotation of sample shapes, a delayed display of comparison shapes, and a mixed use of original and reflected sample shapes did not lead to a rotation effect in pigeons. With arbitrarily different odd comparison shapes, neither humans nor pigeons showed a rotation effect. Final experiments supported the possibility that the complete absence of a rotation effect in pigeons is because they are relatively better than humans at discriminating mirror-image shapes compared with arbitrary shapes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Frequency ratio discrimination by zebra finches (Taeniopygia guttata) and humans (Homo sapiens).

We present the first evidence that songbirds can categorize stimulus sequences (note pairs) by frequency ratio (relative pitch) in an operant discrimination. Zebra finches (Taeniopygia guttata) and humans (Homo sapiens) were trained in a discrimination among 27 synthesized note pairs (9 S+ and 18 S– note pairs) with an operant go-no-go food-reward procedure. In the consistent-ratio discrimination groups, S+ note pairs had a common frequency ratio (1.12). In the jumbled-ratio discrimination group, S+ note pairs varied in frequency ratio (1.00, 1.12, and 1.26). Zebra finches and humans discriminated at least 8 of 9 consistent-ratio S+s, zebra finches discriminated 4 jumbled-ratio S+s, and humans discriminated few or no jumbled-ratio S+s. In this experiment, both species appeared to categorize note pairs by a consistent frequency ratio, but only zebra finches memorized several note pairs individually by rote. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perception of chirps by Sykes's monkeys (Cercopithecus albogularis) and humans (Homo sapiens).

Four Sykes's monkeys (Cercopithecus albogularis) and 4 humans (Homo sapiens) discriminated among 12 chirps presented in a repeating background paradigm. The test stimuli consisted of sets of 4 chirps recorded from Sykes's monkeys, red-tailed monkeys (C. ascanius), and small East African birds. Reaction times (RTs) were submitted to a multidimensional scaling analysis. All monkey listeners perceived the bird chirps as similar to each other and distinct from the monkey calls, whereas 3 of the 4 human listeners had difficulty distinguishing the bird chirps from the monkey calls. Both human and monkey subjects tended to perceive Sykes's and red-tailed monkey calls as very similar to one another, but the degree of perceived similarity was greatest for the monkey listeners. The data suggest that the perceptual map of these calls is influenced by their biological significance in nature. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit and explicit category learning by macaques (Macaca mulatta) and humans (Homo sapiens).

An influential theoretical perspective differentiates in humans an explicit, rule-based system of category learning from an implicit system that slowly associates different regions of perceptual space with different response outputs. This perspective was extended for the 1st time to the category learning of nonhuman primates. Humans (Homo sapiens) and macaques (Macaca mulatta) learned categories composed of sine-wave gratings that varied across trials in bar width and bar orientation. The categories had either a single-dimensional, rule-based solution or a two-dimensional, information-integration solution. Humans strongly dimensionalized the stimuli and learned the rule-based task far more quickly. Six macaques showed the same performance advantage in the rule-based task. In humans, rule-based category learning is linked to explicit cognition, consciousness, and declarative reports about the contents of cognition. These results demonstrate an empirical continuity between human and nonhuman primate cognition, suggesting that nonhuman primates may have some structural components of humans’ capacity for explicit cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanisms of inferential order judgments in humans (Homo sapiens) and rhesus monkeys (Macaca mulatta).

If A > B, and B > C, it follows logically that A > C. The process of reaching that conclusion is called transitive inference (TI). Several mechanisms have been offered to explain transitive performance. Scanning models claim that the list is scanned from the ends of the list inward until a match is found. Positional discrimination models claim that positional uncertainty accounts for accuracy and reaction time patterns. In Experiment 1, we trained rhesus monkeys (Macaca mulatta) and humans (Homo sapiens) on adjacent pairs (e.g., AB, BC, CD, DE, EF) and tested them with previously untrained nonadjacent pairs (e.g., BD). In Experiment 2, we trained a second list and tested with nonadjacent pairs selected between lists (e.g., B from List 1, D from List 2). We then introduced associative competition between adjacent items in Experiment 3 by training 2 items per position (e.g., B?C?, B?C?) before testing with untrained nonadjacent items. In all 3 experiments, humans and monkeys showed distance effects in which accuracy increased, and reaction time decreased, as the distance between items in each pair increased (e.g., BD vs. BE). In Experiment 4, we trained adjacent pairs with separate 9- and 5-item lists. We then tested with nonadjacent pairs selected between lists to determine whether list items were chosen according to their absolute position (e.g., D, 5-item list > E, 9-item list), or their relative position (e.g., D, 5-item list     

The learning of exclusive-or categories by monkeys (Macaca mulatta) and humans (Homo sapiens).

A central question in categorization research concerns the categories that animals and humans learn naturally and well. Here, the authors examined monkeys' (Macaca mulatta) and humans' (Homo sapiens) learning of the important class of exclusive-or (XOR) categories. Both species exhibited—through a sustained level of ongoing errors—substantial difficulty learning XOR category tasks at 3 stimulus dimensionalities. Clearly, both species brought a linear-separability constraint to XOR category learning. This constraint illuminates the primate category-learning system from which that of humans arose, and it has theoretical implications concerning the evolution of cognitive systems for categorization. The present data also clarify the role of exemplar-specific processes in fully explaining XOR category learning, and suggest that humans sometimes overcome their linear-separability constraint through the use of language and verbalization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Seeing and knowing: Knowledge attribution versus stimulus control in adult humans (Homo sapiens).

Interest in cognition in nonhuman animals has inspired new approaches to discovering animals' ability to attribute knowledge to others (e.g., D. J. Povinelli, K. E. Nelson, & S. T. Boysen; see record 1991-00392-001). The assumptions of such experiments were tested in this study by training a group of humans (Homo sapiens) to use accurate information provided by a confederate who was watching as 1 container among 4 was baited; a 2nd group was similarly trained to use accurate information provided by a confederate whose back was turned during baiting. On a single reversal trial, the roles of the 2 confederates were switched. Subjects were able to learn their respective tasks but attended to different aspects of the confederates, as revealed by the reversal trial. Although attributional interpretations can be applied to such data, many of the choices in this experiment can be explained more readily with the basic principles of contingency-based learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Female condition influences preferences for sexual dimorphism in faces of male humans (Homo sapiens).

In some species, female condition correlates positively with preferences for male secondary sexual traits. Women's preferences for sexually dimorphic characteristics in male faces (facial masculinity) have recently been reported to covary with self-reported attractiveness. As women's attractiveness has been proposed to signal reproductive condition, the findings in human (Homo sapiens) and other species may reflect similar processes. The current study investigated whether the covariation between condition and preferences for masculinity would generalize to 2 further measures of female attractiveness: other-rated facial attractiveness and waist-to-hip ratio (WHR). Women with high (unattractive) WHR and/or relatively low other-rated facial attractiveness preferred more "feminine" male faces when choosing faces for a long-term relationship than when choosing for a short-term relationship, possibly reflecting diverse tactics in female mate choice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Determinants of recognition of gestural signs in an artificial language by Atlantic bottle-nosed dolphins (Tursiops truncatus) and humans (Homo sapiens).

Responses of Atlantic bottle-nosed dolphins (Tursiops truncatus) and of humans were collected and analyzed in order to determine the features required for recognition and discrimination of signs (hand signals) in an artificial gestural communication system. Subjects responded to systematically modified signs in which sign components were contrasted for competitive feature salience. One dolphin, with 6 yrs of training in the language, was shown these modified signs intermixed with normal signs in a linguistic, sentence-comprehension context. A second dolphin, familiar with action signs only and with no sentence-comprehension training, served as a nonlingual control. Human subjects were tested in two parallel tasks. The dolphin with sign-language experience attended to (in order of importance) location, completed temporal pattern, gross motor motion, and direction of motion, as salient features. Fine motor motion, hand shape, and hand orientation were less salient. The non-sign-language dolphin attended to all sign features equally and was unaffected by temporal pattern changes. Humans tested in a linguistic context attended to (in order) gross motor motion, location, and an interaction of fine motor motion, hand shape, and hand orientation. Direction of motion and temporal pattern were not salient. Nonlinguistic-context humans attended to all sign features equally and were unaffected by temporal pattern changes. Results indicate that language experience and/or testing context affect feature salience for sign recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The comparative psychology of same-different judgments by humans (Homo sapiens) and monkeys (Macaca mulatta).

The authors compared the performance of humans and monkeys in a Same-Different task. They evaluated the hypothesis that for humans the Same-Different concept is qualitative, categorical, and rule-based, so that humans distinguish 0-disparity pairs (i.e., same) from pairs with any discernible disparity (i.e., different); whereas for monkeys the Same-Different concept is quantitative, continuous, and similarity-based, so that monkeys distinguish small-disparity pairs (i.e., similar) from pairs with a large disparity (i.e., dissimilar). The results supported the hypothesis. Monkeys, more than humans, showed a gradual transition from same to different categories and an inclusive criterion for responding Same. The results have implications for comparing Same-Different performances across species--different species may not always construe or perform even identical tasks in the same way. In particular, humans may especially apply qualitative, rule-based frameworks to cognitive tasks like Same-Different. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Frequency-dependent performance and handedness in professional baseball players (Homo sapiens).

I used data on handedness and pitching and hitting performance in annual cohorts of professional baseball players (1957-2005) to test the hypothesis that handedness among pitchers was subject to negative frequency-dependent selection. As predicted by this hypothesis, right-handed pitchers were more successful (i.e., opposing batters hit more poorly against them) when they were relatively rare in the population. Contrary to the predictions of this hypothesis, however, left-handed pitchers were more successful when they were relatively common. Both right- and left-handed batters performed better in years dominated by right-handed pitchers, despite the fact that right-handed batters perform relatively poorly against right-handed pitchers. I suggest that batters form cognitive representations based on pitcher handedness, and that these representations are strengthened by repeated exposure or priming. When the pitcher handedness polymorphism is more balanced (e.g., 67% right-handed, 33% left-handed), these cognitive representations are less effective, which leads to decreased batting averages and improved performance by all pitchers. Furthermore, these cognitive representations are likely to be more critical to the success of right-handed hitters, who have reduced visuomotor skills relative to left-handed hitters. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Olfactory discrimination of mouse strains (Mus musculus) and major histocompatibility types by humans (Homo sapiens).

Examined, in 5 experiments, whether the olfactory differences apparent to mice are also accessible to humans, using a total of 63 human Ss. In Exp I, Ss were asked to distinguish between the whole-body odors of live mice differing genetically only at the major histocompatibility gene complex (H-2). In Exps II and III, the odor source was mouse fecal pellets, and in Exps IV and V, the odor source was mouse urine. Results reveal that humans can use olfaction to discriminate closely related strains of mice. The possibility that excreted metabolites with characteristic odors may have predated the evolution of an adaptive function for these odors in social communication is suggested. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perception of cliff swallow calls by birds (Hirundo pyrrhonota and Sturnus vulgaris) and humans (Homo sapiens).

Tested for species differences in the perception of the cliff swallow chick begging call. One cliff swallow, 3 European starling, and 3 human Ss were trained on go–no-go or repeating background tasks to discriminate between all possible stimulus pairs, measured by percentage of correct response and latency. Multidimensional scaling was used to convert the similarity measures into a 2-dimensional map for each S. Most of the maps were significantly correlated in Dimension 1 but not in Dimension 2. A cluster analysis separated bird and human maps. To identify the most important acoustic cues for each S, the coordinates of each dimension were regressed on acoustic variables measured from the stimuli. For all Ss, center frequency was Dimension 1. Different acoustic cues were associated with Dimension 2, with agreement only on bandwidth, by the cliff swallow and 1 starling. (PsycINFO Database Record (c) 2010 APA, all rights reserved)