Stimulus control of predatory behavior by the Iberian wall lizard (Podarcis hispanica, Sauria, Lacertidae): Effects of familiarity with prey.

The authors examine the relative roles of vision and chemoreception and the influence of previous experience with prey on the predatory behavior of Iberian wall lizards (Podarcis hispanica). Experiment 1 compared the responses to visual, chemical, and a combination of visual and chemical cues of a familiar prey by 2 groups of lizards that had been kept in captivity for either 3 months or 21 days. Experiment 2 assessed the responses of lizards kept in the laboratory for more than 3 months to a novel prey species. The results reveal that feeding on a prey species affects the lizards' responses to chemical stimuli from that prey. The response to chemical cues of a novel prey requires a 1st-feeding experience with that prey. Lizards that have been fed the same prey species for several months cease responding to the chemical stimuli of that particular prey. (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)     

Discrimination of video images by zebra finches (Taeniopygia guttata): Direct evidence from song performance.

Adult male zebra finches (Taeniopygia guttata) were found to work for the reward of viewing silent video images. In addition, birds that were exposed either passively or contingently upon key pecking to an array of moving images randomly displayed on a video monitor responded with song, depending on the content of the images. In both Experiment 1 (with full-screen images) and Experiment 2 (with sections of images), the subjects clearly discriminated between bird and nonbird pictures. Stimulus movement was found to affect the response only when bird pictures were presented, thus ruling out the evidence for species recognition. The methodology offers a new behavioral assay for investigating categorical perception of pictorial stimuli by songbirds. It has also the potential to provide further insights into the role of visual cues in song learning and social interactions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual mediational instruction: Reducing interference within visual and aural multiple-discrimination tasks.

In two investigations, involving 50 male and 50 female college undergraduate subjects 18–24 years old, we compared differences in the learning of a highly interfering paired-associate discrimination task with and without the use of visual mediational cues. In computerized training, subjects were taught to discriminate between various International Morse Code symbols, given visually and/or aurally, and to respond with the appropriate paired letter of the alphabet. When presented with visual stimuli during a test situation, those subjects taught to use visual mediators significantly increased correct discriminations immediately, as well as 7 and 90 days after training. In addition, when given only aural stimuli during a test situation, those subjects previously trained with visual mediators recalled significantly more correct responses than those receiving training involving only aural or visual stimuli. Visual mediational instruction was shown to significantly reduce interference between the highly similar Morse Code symbols and to facilitate their association with the proper alphabet letter. Further research and applications of mediational instruction are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of vaginal secretion in hamster sexual behavior: Males' responses to normal and vaginectomized females and their odors.

Two experiments (with 60 adult male hamsters and 4 sexually naive male hamsters) examined the importance of vaginal secretion relative to other feminine odors for attraction of males and elicitation of copulatory behavior by comparing the behavior of males toward normal females with that toward vaginectomized Ss. Males were more attracted to intact females than to vaginectomized Ss when odors were the only cues available and also when auditory, visual, and odor cues were available but contact was prevented. There were no differences in the attractiveness of estrous and diestrous Ss whether intact or vaginectomized. When males and females were allowed to interact, there were no differences in any measures of male sexual behavior toward normal vs vaginectomized females, which indicates that the presence of vaginal secretion is not necessary for male sexual behavior. The significance for conceptions of pheromone action in mammals is discussed. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparative analysis of the categorization of multidimensional stimuli: II. Strategic information search in humans (Homo sapiens) but not in pigeons (Columba livia).

Pigeons and undergraduates learned conditional discriminations involving multiple spatially separated stimulus dimensions. Under some conditions, the dimensions were made available sequentially. In 3 experiments, the dimensions were all perfectly valid predictors of the response that would be reinforced and mutually redundant; in 2 others, they varied in validity. In tests with stimuli in which 1 of the 3 dimensions took an anomalous value, most but not all individuals of both species categorized them in terms of single dimensions. When information was delivered as a function of the passage of time, some students, but no pigeons, waited for the most useful information, especially when the cues differed in objective validity. When the subjects could control information delivery, both species obtained information selectively. When cue validities varied, almost all students tended to choose the most valid cues, and when all cues were valid, some chose the cues by which they classified test stimuli. Only a few pigeons chose the most useful information in either situation. Despite their tendency to unidimensional categorization, the pigeons showed no evidence of rule-governed behavior, but students followed a simple “take-the-best” rule. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feature modulation search: A novel memory search model that extends the perceptual interference effect to musical stimuli.

Although most research in the perceptual interference literature has used visual stimuli, recent experiments have replicated this effect using musical stimuli. Two experiments investigated whether musical and visual demonstrations of the effect are produced by a common mechanism by examining whether the provision of incorrect cues would impair melodic object identification in the perceptual interference paradigm. Whereas incorrect cues typically do not affect visual object identification, they reduced melody identification both when the subjects generated the cues and when the experimenter provided them. A novel model (feature modulation search) is presented to account for perceptual interference in musical stimuli. The model has potential applications for the larger perceptual interference literature and for related phenomena in which target-related information impairs cognition. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Decoding discrepant nonverbal cues.

Developed a videotaped test of accuracy in decoding discrepant auditory and visual nonverbal cues (the Nonverbal Discrepancy Test). In three-quarters of the test items, the affect communicated in the audio modality is incongruent with the affect communicated in the video modality. In Study 1, with 41 college students, some Ss saw only the video portion of the test, some heard only the audio portion, and others judged both the audio and the video cues. Intergroup comparisons showed that Ss were more influenced by video cues than by audio cues (video primacy effect). In Study 2, 73 junior high school Ss, 150 high school Ss, and 95 college Ss took the full discrepancy test. In all 3 samples, Ss' judgments of the affects communicated in the discrepancy test were again more influenced by video cues than by audio cues. There was more video primacy for females than for males, for discrepancies involving the face than for discrepancies involving the body, and for discrepancies concerning degree of positivity than for discrepancies concerning degree of dominance. In decoding very discrepant messages, as compared to slightly discrepant ones, Ss adopted a strategy characteristic of judges of deception: They attended relatively more to the audio cues than to the video cues. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The disassociation of visual and acoustic conspecific cues decreases discrimination by female zebra finches (Taeniopygia guttata).

Female zebra finches (Taeniopygia guttata) use visual and acoustic traits for accurate recognition of male conspecifics. Evidence from video playbacks confirms that both sensory modalities are important for conspecific and species discrimination, but experimental evidence of the individual roles of these cue types affecting live conspecific recognition is limited. In a spatial paradigm to test discrimination, the authors used live male zebra finch stimuli of 2 color morphs, wild-type (conspecific) and white with a painted black beak (foreign), producing 1 of 2 vocalization types: songs and calls learned from zebra finch parents (conspecific) or cross-fostered songs and calls learned from Bengalese finch (Lonchura striata vars. domestica) foster parents (foreign). The authors found that female zebra finches consistently preferred males with conspecific visual and acoustic cues over males with foreign cues, but did not discriminate when the conspecific and foreign visual and acoustic cues were mismatched. These results indicate the importance of both visual and acoustic features for female zebra finches when discriminating between live conspecific males. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning in rats with caudate-putamen lesions: Unimpaired classical conditioning and beneficial effects of redundant stimulus cues on instrumental and spatial learning deficits.

The effects of caudate-putamen lesions in the rat on conditioning were investigated in 3 experiments. In Exp I, rats with lesions were impaired on a spatial task that required learning to make the correct position response, but no deficit was obtained when the alternatives were differentiated by salient visual cues. Performance remained good even when the visual cues were removed. A classical conditioned suppression paradigm was used in Exp II, and caudate-putamen lesions were found not to impair acquisition of suppression or overshadowing. In Exp III poor instrumental learning in subjects with lesions as retarded acquisition of lever-press responding and depressed variable interval response rates were found. When a light stimulus was present together with reinforced responses, response rates were depressed in the control group (which suggested an overshadowing phenomenon) but were potentiated in the group with lesions. Results show that caudate-putamen lesions did not produce a general deficit in association formation. There was disruption of learning about responses but not stimuli and, moreover, it was found that redundant stimulus cues aided response learning. It appears that for normal subjects, the salience or associability of the response cues may largely-determine the influence of stimuli presented during instrumental conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The perceived rigidity of rotating eight-vertex geometric forms: extracting nonrigid structure from rigid motion

In four experiments, subjects examined four categories of rotating eight-vertex geometric forms in parallel projection. Some of the figures appeared to deform, even though rigid three-dimensional interpretations were possible mathematically. Our results from several deformation-rating tasks indicated that most of the configurations maintained a rigid appearance throughout their rotations, although one category of stimuli appeared to deform more frequently than the others. Configurations from the category that contained a high proportion of stimuli that appeared to deform were also shown to be more difficult to discriminate from stimuli that had no rigid three-dimensional interpretation (measured using a signal detection task). To account for these findings, a theory was formulated based on the use of monocular depth cues in the perception of shape. Static monocular depth cues we define as those which are present in non-moving stimuli and Dynamic monocular depth cues are those that are only present in moving stimuli. We conclude that static cues dominate the perception of shape when humans respond to parallel (and, most likely, polar) projections of rotating objects with rigid three-dimensional interpretations. Further, subjects cannot respond to the motion or acceleration profile of part of such a stimulus without responding to the figure as a whole.     

Selective responding by autistic children to multiple sensory input.

Reinforced 6 autistic, 5 retarded, and 5 normal children for responding to a complex stimulus involving the simultaneous presentation of auditory, visual, and tactile cues. After discrimination was established, elements of the complex were presented separately to assess which aspects of the complex stimulus had acquired control over the S's behavior. It was found that (a) the autistics responded primarily to only 1 of the cues, normals to all 3 cues, and retardates to 2 cues; and (b) conditions could be arranged such that a cue which had remained nonfunctional when presented in association with other cues could be established as functional when trained separately. Data fail to support theories that any 1 sense modality is impaired in autistic children. When presented with a stimulus complex, autistic Ss' attention was overselective. Findings are related to the literature on selective attention. Since much learning involves contiguous or near-contiguous pairing of 2 or more stimuli, failure to respond to 1 of the stimuli may be an important factor in the development of autism. (27 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of inter- and intramodal selective attention to non-spatial visual stimuli: an event-related potential analysis

Event-related potentials (ERPs) were recorded to trains of rapidly presented auditory and visual stimuli. ERPs in conditions in which subjects attended to different features of visual stimuli were compared with ERPs to the same type of stimuli when subjects attended to different features of auditory stimuli. This design permitted us to study effects of variations in both intramodal and intermodal visual attention on the timing and topography of ERP components in the same experiment. There were no indications that exogenous N110, P140 and N180 components to line gratings of high and low spatial frequencies were modulated by either intra- or intermodal forms of attention. Furthermore, intramodal and intermodal attention effects on ERPs showed similar topographical distributions. These combined findings suggest that the same neural generators in extrastriate occipital areas are involved in both forms of attention. Visual ERPs elicited in the condition in which subjects were engaged in auditory selective attention showed a large positive displacement at the occipital scalp sites relative to ERPs to attended and unattended stimuli in the visual condition. The early onset of this positivity might be associated with a highly confident and early rejection of the irrelevant visual stimuli, when these stimuli are presented among auditory stimuli. In addition, the later onset of selection potentials in the intramodal condition suggests that a more precise stimulus selection is needed when features of visual stimuli are rejected among other features of the same stimulus pattern, than when visual stimuli are rejected among stimuli of another modality.     

The visual control of reaching and grasping: Binocular disparity and motion parallax.

The primary visual sources of depth and size information are binocular cues and motion parallax. Here, the authors determine the efficacy of these cues to control prehension by presenting them in isolation from other visual cues. When only binocular cues were available, reaches showed normal scaling of the transport and grasp components with object distance and size. However, when only motion parallax was available, only the transpont component scaled reliably. No additional increase in scaling was found when both cues were available simultaneously. Therefore, although equivalent information is available from binocular and motion parallax information, the latter may be of relatively limited use for the control of the grasp. Binocular disparity appears selectively important for the control of the grasp. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The forked tongue and edge detection in snakes (Crotalus oreganus): An experimental test.

Many stimulus-detection systems are lateralized to allow for simultaneous comparison of paired stimuli. It has been hypothesized that the deeply forked tongue of snakes and some derived lizards functions as a chemical edge detector where cues gathered by each tine are kept separate to provide two points of lateral odor assessment by the central nervous system via vomeronasal input. While following a chemical trail, one time can be on the trail, the other off, and such differential information prompts the snake to turn back to the trail. The authors tested this hypothesis in rattlesnakes within a predatory context by unilaterally severing the vomeronasal nerves. If edge detection is used by snakes during prey trailing, then unilateral denervation should disrupt trailing ability. The authors found no change in the seven separate trailing parameters measured. Therefore, they found no support for the edge detection hypothesis as it applies to prey trailing behavior. Instead, the deeply forked tongue may represent a chemosensory specialization to increase odor-sampling area, with snakes and derived lizards detecting only the concentration of chemical trails. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Treatment of lymphoid malignancies in patients with ataxia-telangiectasia

The present study tested the idea that if subjects rely more on scene-based pictorial cues when binocular cues are not available, then both their perceptual judgements and their grasp might be influenced by pictorial illusions such as the Ebbinghaus (Titchener) Circles Illusion under monocular viewing conditions. Under binocular viewing conditions, subjects were always able to scale their grip accurately to the true size of the target disc and were unaffected by the illusion. Under monocular viewing, however, subjects appeared to be influenced by the illusion. Thus, when confronted with physically different target discs displayed on backgrounds that made them appear equivalent in size, subjects treated the two discs as equivalent--even when picking them up. These results, combined with earlier work from our laboratory suggests that binocular information plays a critical role in normal human prehension but when this information is not available the visuomotor system is able to "fall back" on the remaining monocular cues, which can cause the visuomotor system to be more susceptible to pictorial illusions.     

Stimulus generalization as a function of stimulus novelty and familiarity in rats.

Three experiments used rats as subjects to investigate the generalization of conditioned responding between stimuli as a function of the subjects' exposure to these cues prior to conditioning. Experiment 1 used a between-subjects design, food as the reinforcer, and measured the tendency of subjects to approach the site of food delivery during the stimuli. Generalization of this response was more marked when the training and test stimuli were equated in terms of their novelty (i.e., when both were novel or both were familiar) than when the stimuli differed in this respect (i.e., when one was novel and the other was familiar). Experiments 2a and 2b used within-subjects designs to confirm the reliability of the results of Experiment 1. Implications of these results for current theories of stimulus representation are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory enhances visual perception: Evidence from signal detection analysis.

We show that perceptual sensitivity to visual stimuli can be modulated by matches between the contents of working memory (WM) and stimuli in the visual field. Observers were presented with an object cue (to hold in WM or to merely attend) and subsequently had to identify a brief target presented within a colored shape. The cue could be re-presented in the display, where it surrounded either the target (on valid trials) or a distractor (on invalid trials). Perceptual identification of the target, as indexed by A′, was enhanced on valid relative to invalid trials but only when the cue was kept in WM. There was minimal effect of the cue when it was merely attended and not kept in WM. Verbal cues were as effective as visual cues at modulating perceptual identification, and the effects were independent of the effects of target saliency. Matches to the contents of WM influenced perceptual sensitivity even under conditions that minimized competition for selecting the target. WM cues were also effective when targets were less likely to fall in a repeated WM stimulus than in other stimuli in the search display. There were no effects of WM on decisional criteria, in contrast to sensitivity. The findings suggest that reentrant feedback from WM can affect early stages of perceptual processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characteristics of perceptual grouping in rats

Parametric analysis was made of the characteristics by which proximity and alignment serve as cues for perceptual grouping in rats. Rats were initially conditioned to discriminate a series of horizontal lines from vertical lines. Following training, rats were presented with test stimuli that consisted of bistable arrays of disjunct dots. A grouping cue (greater proximity, greater alignment, or both) was randomly assigned to either the horizontal or vertical orientation. The effectiveness of the cues was based on behavioral responses to the cued orientation. Results indicated that proximity served as a cue for perceptual grouping. The effectiveness of the proximity cue was less for rats than found previously in humans and, unlike humans, diminished with increased stimulus scale. Rats did not respond to alignment cues when used in isolation, although alignment facilitated grouping when used in conjunction with proximity cues. Diminished effectiveness of grouping cues likely reduces object recognition abilities, particularly for complex visual stimuli.