Human listeners provide insights into echo features used by dolphins (Tursiops truncatus) to discriminate among objects.

Echolocating bottlenose dolphins (Tursiops truncatus) discriminate between objects on the basis of the echoes reflected by the objects. However, it is not clear which echo features are important for object discrimination. To gain insight into the salient features, the authors had a dolphin perform a match-to-sample task and then presented human listeners with echoes from the same objects used in the dolphin's task. In 2 experiments, human listeners performed as well or better than the dolphin at discriminating objects, and they reported the salient acoustic cues. The error patterns of the humans and the dolphin were compared to determine which acoustic features were likely to have been used by the dolphin. The results indicate that the dolphin did not appear to use overall echo amplitude, but that it attended to the pattern of changes in the echoes across different object orientations. Human listeners can quickly identify salient combinations of echo features that permit object discrimination, which can be used to generate hypotheses that can be tested using dolphins as subjects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Matching-to-sample by an echolocating dolphin (Tursiops truncatus).

An adult male dolphin was trained to perform a three-alternative delayed matching-to-sample task while wearing eyecups to occlude its vision. Sample and comparison stimuli consisted of a small and a large plastic tube, a water-filled stainless steel sphere, and a solid aluminum cone. Stimuli were presented under water and the dolphin was allowed to identify the stimuli through echolocation. The echolocation clicks emitted by the dolphin to each sample and each comparison stimulus were recorded and analyzed. Over 48 sessions of testing, choice accuracy averaged 94.5% correct. This high level of accuracy was apparently achieved by varying the number of echolocation clicks emitted to various stimuli. Performance appeared to reflect a pre-experimental stereotyped search pattern that dictated the order in which comparison items were examined and a complex sequential-sampling decision process. A model for the dolphin's decision-making processes is described. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interference from irrelevant features on visual discrimination by macaques (Macaca fuscata): A behavioral analogue of the human Stroop effect.

To study the operation of selective attention in a conflict situation with automatic processes, we trained 4 Japanese macaques; (Macaca fuscata) extensively on a manual go/no-go task. The monkey had to discriminate either the color, shape, motion direction, or location of a visual stimulus. In each trial, the behavioral meaning of the relevant feature (go or no-go) could either be congruent or incongruent with irrelevant features of the same stimulus. Reaction times were slowed, and error rates increased when irrelevant stimulus features were incongruent with the required response. The effects were obtained when the monkey attended to the color, shape, or motion direction, but not when it attended to the location of the stimulus. The effects were cumulative so that the interference from 1 incongruent feature was smaller than that from 2 incongruent features. We propose that the present paradigm provides a behavioral analogue of the human Stroop effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recent use of signs by chimpanzees (Pan troglodytes) in interactions with humans.

In light of the controversy about the linguistic properties of chimpanzee signing behavior, the recent sign use of 5 chimpanzees (Pan troglodytes) with long histories of sign use was analyzed while they interacted with longtime human companions. Four corpora from 1992 to 1999 consisting of 3,448 sign utterances were examined. The chimpanzees predominantly used object and action signs. There was no evidence for semantic or syntactic structure in combinations of signs. Longer combinations showed repetition and stringing of object and action signs. The chimpanzees mostly signed with an acquisitive motivation. Requests for objects and actions were the predominant communicative intentions of the sign utterances, though naming and answering also occurred. This recent sign use shows multiple differences with (early) human language. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feature distribution and biased estimation of visual displays.

Perceptual equivalents of confirmation biases and framing effects are observed in Ss' estimates of feature numerosity. Ss are asked to estimate the percentage of display items that have a particular feature. Features either are randomly distributed or are spatially clustered such that features of the same type tend to be close. Ss systematically overestimate the prevalence of features in clustered displays. The pattern of results is best explained by a regional salience bias: Features tend to be more salient if they belong to regions that have a high concentration of instruction-mentioned features. The regional salience bias is contrasted with a feature salience bias: Features tend to be more salient if they are mentioned in the instructions. The relations among the observed perceptual bias and traditional confirmation biases, numeric estimation, and attention are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of perceptual salience on reflective-impulse performance differences.

Examined the relationship between perceptual salience and cognitive style in 31 1st graders, 37 3rd graders, and 37 5th graders who had been classified as impulsive or reflective based on scores on the Matching Familiar Figures Test. After determining salience hierarchy scores, Ss were given a modified matching test. This test consisted of 3 trial types on which the S's most salient, least salient, or both most and least salient dimensions were necessary for making a correct match. Impulsives made more errors than reflectives only on trials requiring the use of the least salient dimension. These performance differences decreased with age. Cognitive style did not affect latencies on the modified matching task. It is concluded that (a) perceptual features of the stimulus situation can markedly influence impulsives' performance, (b) cognitive style effects were not attributable to differences in the salience hierarchies of reflective-impulsive Ss, (c) cognitive style differences can occur in the absence of latency differences, and (d) sensitization to perceptual features may be an effective means of improving impulsives' performance. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavioral preferences in response to social injustice: The effects of group permeability and social identity salience.

Examined features of an intergroup context that can affect people's preferred responses to a situation of social injustice. 90 undergraduates were randomly assigned to 1 of 3 conditions of group permeability (open, token, or closed) and 1 of 2 conditions of social identity salience (not salient or salient). It was predicted on the basis of social identity theory that individualistic responses would be preferred to a collective response when group boundaries were more open but not when they were closed. It was also expected that under conditions of group impermeability, collective behavior would be preferred to a greater extent by individuals for whom social identity was salient than by individuals for whom it was not salient. The results, which generally supported these hypotheses, are discussed in terms of social psychological theories of intergroup relations and also with regard to their potential practical implications. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chimpanzee (Pan troglodytes) handedness: Variability across multiple measures of hand use.

This study examined intertask consistency in handedness across multiple measures of hand use in a sample of 187 chimpanzees (Pan troglodytes). Hand preferences for 2 to 6 measures were collected from the sample, and hand preference scores were derived on the basis of the individual hand preferences for each measure. Seven of 15 possible intratask correlations were significant, with some degree of clustering depending on the motor demands of the tasks. Two overall measures of handedness revealed population-level right-handedness in the chimpanzees, although the degree of bias was reduced for chimpanzees tested on more than 3 measures of hand use. The results are interpreted in the context of several recent studies that proposed theoretical models of handedness in nonhuman primates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Note on hand use in the manipulation of joysticks by rhesus monkeys (Macaca mulatta) and chimpanzees (Pan troglodytes).

In a recent article MacNeilage, Studdert-Kennedy, and Lindblom (1987) proposed that nonhuman primate handedness may be contingent on the specific task requirements with visual–spatial tasks yielding left-hand preferences and fine motor tasks producing right-hand preferences. This study reports hand preferences in the manipulation of joysticks by 2 rhesus monkeys (Macaca mulatta) and 3 chimpanzees (Pan troglodytes). Reach data were collected on these same subjects and served as a basis for comparison with preference data for manipulation of the joystick. The data indicated that all 5 subjects demonstrated significant right-hand preferences in manipulating the joystick. In contrast, no significant hand preferences were found for the reach data. Reaction time (RT) data also indicated that the right could perform a perceptual–motor task better than the left hand in all 5 subjects. Overall, the data indicate that reach tasks may not be sensitive enough measures to produce reliable hand preferences, whereas tasks that assess fine motor control produce significant hand preferences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of context salience on heart rate orienting and habituation in preweanling and periadolescent rats.

Previous research indicates that target learning is facilitated in the presence of strong extraneous sensory cues (e.g., salient contextual cues) in infant, but not adult, rats (McKinzie & Spear, 1995). The present study assessed whether such facilitation of conditioning is due to age-related differences in the effect of a salient context on processing of the conditioned stimulus (tone in this case). Preweanling and periadolescent rats were presented with a tone in either the presence (salient context) or absence (plain context) of a potent odorant. Magnitude of the heart rate orienting response to the target stimulus and its subsequent rate of habituation served as dependent variables. The results revealed that preweanling, but not periadolescent, rats showed greater cardiac orienting to the auditory stimulus in the salient than in the plain context. The results suggest that a salient context may influence stimulus processing by increasing the perceived salience and, perhaps in terms of perceived intensity, of the target stimulus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pitch and time, tonality and meter: How do musical dimensions combine?

The authors examined how the structural attributes of tonality and meter influence musical pitch–time relations. Listeners heard a musical context followed by probe events that varied in pitch class and temporal position. Tonal and metric hierarchies contributed additively to the goodness-of-fit of probes, with pitch class exerting a stronger influence than temporal position (Experiment 1), even when listeners attempted to ignore pitch (Experiment 2). Speeded classification tasks confirmed this asymmetry. Temporal classification was biased by tonal stability (Experiment 3), but pitch classification was unaffected by temporal position (Experiment 4). Experiments 5 and 6 ruled out explanations based on the presence of pitch classes and temporal positions in the context, unequal stimulus quantity, and discriminability. The authors discuss how typical Western music biases attention toward pitch and distinguish between dimensional discriminability and salience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Factors influencing imitation of manipulatory actions in chimpanzees (Pan troglodytes).

The purpose of the study was to investigate what kind of factors determine the degree of difficulty for chimpanzees (Pan troglodytes) when they imitate actions. Five adult chimpanzees were instructed to perform 48 arbitrary manipulatory actions consisting of different bodily motor patterns and object directionality. Results showed that actions in which an object is directed toward another external location (another object and one's own body) were easier to perform than those that involved manipulating a single object alone. Actions involving unfamiliar motor patterns were more difficult to perform than those involving familiar motor patterns that were already present in the subject's repertoire. Error responses were characterized as perseverative repetition of previously instructed actions. These findings suggest that chimpanzees find the directionality of manipulated objects a more salient cue than details of the demonstrator's body movements performing the manipulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

N-methyl-D-aspartate-mediated bulbospinal respiratory drive is pH/P(CO2)-insensitive in turtle brainstem-spinal cord

Twenty-four autopsied cases of lethal closed head trauma occurring sufficiently rapidly for the salient pathologic features to remain unobscured by medical intervention, and selected to exclude the possibility of exsanguination by other means, were analyzed for the presence or absence of exsanguination from basal skull fracture. The purpose of this study was to test the validity of the "Empty Heart" sign in head injuries, attributed by Hirsch and Zumwalt [C.S., Hirsch, R.E., Zumwalt, The "Empty Heart" sign. The American Journal of Forensic Medicine and Pathology 7 (2) (1986) 112-114] to a hypothetical neurologic reflex causing occult intra-corporeal sequestration of blood. The study revealed that the twelve cases with more severe injuries showed clear cut exsanguination (with "empty" hearts) due to basal skull fractures, while the twelve milder injury cases showed no signs of exsanguination, including the empty heart sign. No cases of cryptogenic empty heart were found. These findings demonstrate that the "empty heart" sign is merely an indication of exsanguination due to basilar skull fracture. The mechanism of exsanguination in these cases is discussed. The author's method for the determination of depleted blood volume at autopsy is described. The routine estimation of blood volume at autopsy and the inclusion of investigative data in forensic case assessment are recommended.     

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perception and generalization of frequency contours by a bottlenose dolphin (Tursiops truncatus).

A single adult female bottlenose dolphin was tested in a series of perceptual studies. On each trial, 4 sine-wave tones were presented that contained a falling frequency contour or some other contour. There were several frequency-transposed exemplars of each contour type in each experiment. The dolphin discriminated contours at a level significantly greater than chance in all experiments. In the 1st 2 experiments, the dolphin demonstrated only modest transfer to novel stimuli and a sensitivity to the absolute frequency of stimuli. In the 3rd experiment, there was no effect of the absolute frequency of stimuli; in the 4th experiment, the dolphin successfully transferred the discrimination to novel stimuli drawn from the octave above the previously heard range. These results demonstrate dolphins' capability to perceive frequency contours, which may underlie the recognition of conspecific whistles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The uncertain response in the bottlenosed dolphin (Tursiops truncatus).

Humans respond adaptively to uncertainty by escaping or seeking additional information. To foster a comparative study of uncertainty processes, we asked whether humans and a bottlenosed dolphin (Tursiops truncatus) would use similarly a psychophysical uncertain response. Human observers and the dolphin were given 2 primary discrimination responses and a way to escape chosen trials into easier ones. Humans escaped sparingly from the most difficult trials near threshold that left them demonstrably uncertain of the stimulus. The dolphin performed nearly identically. The behavior of both species is considered from the perspectives of signal detection theory and optimality theory, and its appropriate interpretation is discussed. Human and dolphin uncertain responses seem to be interesting cognitive analogs and may depend on cognitive or controlled decisional mechanisms. The capacity to monitor ongoing cognition, and use uncertainty appropriately, would be a valuable adaptation for animal minds. This recommends uncertainty processes as an important but neglected area for future comparative research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hearing status and language fluency as predictors of automatic word and sign recognition

In previous studies, evidence concerning the extent of automatic word recognition in deaf children and the influence of language fluency on word and sign recognition (as indexed by the Stroop task) has been contradictory. This study examined the effects of English and sign language fluency in the automatic word and sign recognition of deaf and hearing adults. Results indicated that responding in sign took longer and created more Stroop interference than responding orally. Two groups of certified interpreters revealed this finding to be independent of hearing status. Most important, deaf subjects showed greater automaticity in recognizing signs than words, whereas hearing subjects showed greater automaticity in recognizing words than signs. This pattern was unaffected by language fluency. The findings clarify the results of previous studies both theoretically and methodologically.     

A vocabulary test for chimpanzees (Pan troglodytes).

Presented a vocabulary test to 4 cross-fostered chimpanzees (4–6 years old) who had learned some American Sign Language (ASL) in the laboratory. 35 mm color slides were projected on a screen that could be seen by the chimpanzee Ss but not by the human observers. There were 2 observers: 01 was the questioner in the testing room with the Ss; 02 was in a different room. Neither observer could see the other, or the responses of the other observer. 01 and 02 agreed in their readings of both correct and incorrect signs, and most of the signs were the correct ASL names of the slides. To show that the chimpanzees were naming natural language categories—that the sign DOG could refer to any dog, FLOWER to any flower, SHOE to any shoe—each test trial was a 1st trial, in that test slides were presented only once. Analysis of errors showed that 2 aspects of the signs, gestural form and conceptual category, governed the distribution of errors. (64 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impact of salient vocal qualities on causal attribution for a speaker's behavior.

Two determinants of auditory salience were manipulated—the intensity and sex of a speaker's voice. 98 college students served as listeners. As predicted, Ss attended more to a 75-db than to a 70-db voice on a binaural listening test, and Ss attributed more causality to an actor in a 2-person conversation when his voice was 75 db in intensity than when it was 70 db. Contrary to expectation, Ss listened more to the actor with the male voice. Consistent with this tendency for the male voice to be more salient, Ss attributed more causality to an actor when the voice was male than when it had been electronically converted to a female voice of the same intensity and intonation. Vocal salience also influenced Ss' impressions of the actors, but it had no impact on recall of the actors' verbalizations. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)