Conspecific recognition in the chimpanzee (Pan troglodytes): cardiac responses to significant others

The ability of a chimpanzee (Pan troglodytes) to recognize photographs of conspecifics was evaluated with heart-rate measures. Heart rate was recorded before, during, and after viewing photographs of an aggressive chimpanzee, a friendly companion animal, and an unfamiliar chimpanzee. The subject displayed a differential pattern of heart-rate response to the stimulus animals, without prior experience with the photographs. Responses to the aggressive animal were acceleratory, which suggests a defensive response. Respiratory sinus arrhythmia suggested that this response was associated with sympathetic activation. In contrast, responses to the familiar animal were minimal, whereas cardiac deceleration was observed in response to the strange chimp, which likely reflects an orienting response. Results suggest the chimpanzee is able to recognize photographs of individual conspecifics and that heart-rate change can reflect the nature of established social relationships between chimpanzees.     

The use of photographs as occupational stimuli

The purpose of this study was to examine the potential of photographic stimuli portraying well-known occupational activities in order to elicit vocationally relevant responses. Color photographs of persons performing occupational tasks or activities were the stimuli used to determine if aspects of the photographs would elicit discriminating responses. Eighty special education high school students were asked individually to respond to 15 color photographs. Out of a maximum of 1200 possible picture identifications, 35 responses were scored incorrect or unknown as to content. These results indicated 97.1% effectiveness in identifying the stimulus content by this population. Therefore, photographs consisting of occupational content can discriminate as stimuli by eliciting content-appropriate responses. Implications for further research and application of this finding are discussed.     

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.     

Why are faces hard to recognize in photographic negative?

Faces may be difficult to recognize in photographic negative simply because they contain a large range of grays, while printed words and geometric shapes, which contain no grays, are easy to recognize in negative. This explanation was partly tested in an experiment where Ss had to recognize positive and negative pictures of well-known people, both using normal monochrome photographs and using lith photographs in which all areas of gray were removed. Lith photographs were harder to recognize than normal photographs, but the difference between positive and negative was the same for lith pictures as for normal ones. This does not rule out an explanation in terms of grays, but it does put a major constraint on it.     

What the face and body reveal: in-group emotion effects and stereotyping of emotion in African American and European American children

This study examined whether 3- to 7-year-old African American and European American children’s assessment of emotion in face-only, face + body, and body-only photographic stimuli was affected by in-group emotion recognition effects and racial or gender stereotyping of emotion. Evidence for racial in-group effects was found, with European American children being more accurate when assessing emotion in European American photographs than African American photographs for some emotions. African American children were either equally proficient in recognizing emotion in African American and European American photographs or were more accurate with European American photographs for some emotions. Stereotyping of emotion was also found, with boys being more often labeled with “masculine” emotions (e.g., mad) and at least some girls being more often labeled with “feminine” emotions (e.g., happy). However, stereotyping effects were found only when the face was present in the stimuli and were not found with body-only stimuli. In-group effects, however, were not affected by type of photograph (face-only, body-only, or face + body), with children being unable to recognize at least some emotions from just the body postures alone (mad). These results have important implications for how future studies assess emotion recognition in children, particularly in terms of how emotion stimuli are constructed, the diversity of the stimuli, and who judges the stimuli.     

Recognition of Line-Drawing Representations by a Chimpanzee (Pan troglodytes)

The ability of a chimpanzee to recognize individuals portrayed in line drawings was evaluated. A 12-year-old female chimpanzee with extensive prior experience in the use of visual symbols matched the line drawings of chimpanzees, humans, and an orangutan with a specific letter of the alphabet. When a line drawing of a familiar individual was presented on the computer screen, the chimpanzee responded by punching a key with the letter of the alphabet that corresponded to the individual's name. Results indicate that the chimpanzee is able to categorize individuals from novel line-drawing representations.     

Development of face recognition in infant chimpanzees (Pan troglodytes)

In this paper, we assessed the developmental changes in face recognition by three infant chimpanzees aged 1–18 weeks, using preferential-looking procedures that measured the infants’ eye- and head-tracking of moving stimuli. In Experiment 1, we prepared photographs of the mother of each infant and an “average” chimpanzee face using computer-graphics technology. Prior to 4 weeks of age, the infants showed few tracking responses and no differential responses. Between 4 and 8 weeks of age, they paid greater attention to their mother's face. From 8 weeks onward, they again showed no differences, but exhibited frequent tracking responses. Experiment 2 investigated the infants’ tracking responses between a familiar human's and an “average” human face. The infants did not show any evidence of recognizing the human faces. We discuss the development of face recognition in relation to the effects of other species’ faces and postnatal visual experience.     

De novo conditioning in trauma-exposed individuals with and without posttraumatic stress disorder

Differential conditioning was assessed in 15 medication-free individuals meeting Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) criteria for chronic posttraumatic stress disorder (PTSD) and 18 trauma-exposed individuals who never developed PTSD (non-PTSD). Conditioned stimuli (CSs) were colored circles, and the unconditioned stimulus was a "highly annoying" electrical stimulus. Individuals with PTSD had higher resting heart rate (HR) and skin conductance (SC) levels and produced larger SC orienting responses. During conditioning, the PTSD group showed larger differential SC, HR, and electromyogram responses to the reinforced vs. nonreinforced stimuli (CS+ vs. CS-) compared with the non-PTSD group. Only PTSD participants continued to show differential SC responses to CS+ vs. CS- during extinction trials. Results suggest that individuals with PTSD have higher sympathetic nervous system arousal at the time of conditioning and are more conditionable than trauma-exposed individuals without PTSD.     

Treatment of escape-maintained aberrant behavior with escape extinction and predictable routines

We evaluated the effects of two daily activity schedules on 2 participants' rates of aberrant behavior and their compliance. Functional analysis identified the operant function of the participants' aberrant behaviors to be escape from tasks. Participants were taught to use stimuli contained in daily schedules, and were tested based on a modified stimulus-equivalence model that consisted of flash cards and activity schedules comprised of words or photographs that corresponded to the participants' daily activities. On pretests, the participants demonstrated simple and conditional discriminations with the photographs but not with the printed stimuli. A time-delay procedure was used to teach the participants to name the flash cards. Following training, the printed activity schedules corresponded to lower rates of problem behavior and higher rates of compliance than the photographic activity schedules. Performance on posttests indicated the establishment of functional classes of stimuli involving the flash cards and activity schedules even though this type of correspondence was not directly trained.     

Effects of presenting incidental information in consequent events on future learning

The effects of presenting future target stimuli in the consequent event following correct responses to current target stimuli were examined in two experiments teaching eight students with moderate handicaps to name photographs. In Experiment I, progressive time delay was used to teach two sets of photographs. During instruction, correct responses to one set of stimuli resulted in praise and presentation of the printed word for the person in the photograph (future condition). In the second set, a correct response was followed by praise alone (non-future condition). After establishing criterion level performance on both sets of photographs, students were taught to read the printed word from each of the two sets. Experiment II was a systematic replication of Experiment I. Four students from a different classroom also were taught to name two sets of photographs. An adapted alternating treatments design was used in each experiment. The results indicated that (a) all students learned to name the photographs; (b) presentation of future target stimuli (words) in consequent events resulted in seven of the eight students learning to read some of the words; and (c) the total number of sessions, trials, errors, and percentage of errors     

A Stroop-like effect in color-naming of color-word lexigrams by a chimpanzee (Pan troglodyte)

The Stroop effect (J. R. Stroop, 1935) reflects the difficulty in ignoring irrelevant, but automatically processed, semantic information that is inherent in certain stimuli. With humans, researchers have found this effect when they asked participants to name the color of the letters that make up a word that is incongruent with that color. The authors tested a chimpanzee that had learned to associate geometric symbols called lexigrams with specific colors. When the chimpanzee had to make different responses that depended on the color of stimuli presented to her, she showed a Stroop-like effect when researchers presented to her the previously learned symbols for colors in incongruent font colors. Her accuracy performance was significantly poorer with these stimuli than with congruent color-referent lexigrams, noncolor-referent lexigrams, and nonlexigram stimuli, although there were not any significant differences in response latency. The authors' results demonstrated color-word interference in a Stroop task with a nonhuman animal.     

Pictures in mind: initial encoding of object properties varies with the realism of the scene stimulus

A fundamental question in perception is how we visually encode and retain information about a complex scene in order to allow effective operation within it. Interestingly, the stimuli used to investigate scene perception have varied greatly between studies, ranging from line drawings to coloured drawings, computer-generated scenes, photographs, and real scenes. Are findings from these different types of scene stimulus equally ecologically valid? Two experiments are reported that address this issue. In the first we compared photographic and non-photographic scenes and found that observers perform better in questions testing object memory when viewing photographs, suggesting an initial benefit for encoding information from photographs. In the second we found that whether or not non-photographic scenes obeyed realistic scene-organising properties influenced object-memory formation. Effects varied for the different question types, but again were most prominent early in viewing. We conclude that in the search for an understanding of everyday scene perception we must be very careful in our choice of scene stimuli and in our interpretation of findings from the laboratory.     

Startle modulation in non-incarcerated men and women with psychopathic traits

Past research has demonstrated that individuals with psychopathic characteristics are under-responsive to aversive stimuli, however, much of this work has failed to include non-incarcerated samples, or to examine gender differences in this relationship. Additionally, few studies have examined the role of specific personality characteristics, as they relate to both psychopathic behavior and emotional responsiveness. The current study assessed emotional modulation of the startle response in a community sample of 108 men and women (99 with usable startle data) during perception of emotion-laden photographs. Consistent with previous work, men reporting high levels of psychopathy failed to show the typical increase in the startle response when exposed to aversive photographs, but only when responses were elicited relatively early in picture viewing (i.e., 2.0 s as compared to 4.5 s post-photograph onset). Additionally, both genders showed a significant effect of harm avoidance and anxiety on modulation of the startle response, such that individuals reporting low levels of each trait failed to show significant responses to aversive photographs. These results suggest that while deficits in emotional processing extend to non-incarcerated samples, the relationship may be influenced by additional factors including gender, personality, and attributes related to incarceration.     

Recognition of positive and negative bandpass-filtered images

A study is reported in which the significance for vision of low- and high-spatial-frequency components of photographic positive and negative images was investigated by measuring recognition of bandpass-filtered photographs of faces. The results show that a 1.5 octave bandpass-filtered image contains sufficient visual information for good recognition performance, provided the filter is centred close to 20 cycles facewidth-1. At low spatial frequencies negatives are more difficult to recognize than positives, but at high spatial frequencies there is no difference in recognition, implying that it is the low-frequency components of negatives which present difficulties for the visual system.     

Manipulation of colour and shape information and its consequence upon recognition and best-likeness judgments

Previous forays into the study of recognition have revealed an advantage for line-drawn and photographic shape caricatures of faces in reaction-time paradigms. When a presentation-time technique was used, photographs with enhanced colour intensity and saturation were also found to provide superior recognition accuracy to veridical images. This has provided strong evidence that distinctive information can produce a recognition advantage for famous faces in both colour and shape domains. Such a presentation-time paradigm allows the display of stimuli over a range of brief display periods. Using this paradigm, subjects recognised photorealistic target faces caricatured in shape with greater accuracy than veridical images, consistent with previous findings when reaction time was used as a measure. Subjects were also asked to identify the best likeness for individuals using photorealistic stimuli and an interactive paradigm with shape caricature, colour caricature, and contrast control varied by the user in real-time. The best likeness with shape manipulation was a slight anticaricature, while with colour-caricature and contrast-control images a mildly exaggerated image was selected as the best likeness. Thus, although images caricatured substantially in colour or shape (+40%) induce superior recognition compared to veridical images, such substantial exaggerations are not necessarily seen as best likenesses under prolonged exposure.     

Anxiety in recovery from severe burn injury: an experimental comparison

Adjustment to burn injury is a slow process that often results in high distress and anxiety. This study aimed to investigate the impact on anxiety of viewing various types of photographic stimuli (including burn injuries), comparing a burn-injured and control sample. An experimental design was used comparing those recovering from a burn injury with age- and gender-matched controls. Thirty participants from a burns support group and their matched controls were asked to complete a trait anxiety measure (STAI Y-2). Participants then completed the state anxiety measure (STAI Y-1) after viewing different types of photographic stimuli (burn injuries, uninjured body parts, neutral) under controlled experimental conditions. Results demonstrated significant differences in anxiety levels between groups with respect to trait anxiety and state anxiety after each experimental condition. Age of injury was also found to be a significant influence over trait anxiety. A significant effect of experimental condition was found, as was a significant interaction between group and condition. Those with burn injuries were more anxious than controls - a difference that was further exaggerated when participants viewed photographs of burned or uninjured body parts in an experimental setting.     

Effect of surface characteristics and style of production on naming and verification of pictorial stimuli.

Theories of object recognition that are based purely on part decomposition do not take into account the role of textural, shading, and color information, nor do they differentiate between stylistic factors in the preparation of line-drawn pictorial stimuli. To investigate these factors, naming and verification experiments were performed using line drawings, monochrome photographs, and color photographs of common objects. For line drawings, it was shown that line width, exposure, and contrast affected naming latency, which increased for lines of narrow width and extremes of exposure. Naming latencies were compared for objects drawn by a professional artist, with varying degrees of surface detail, and objects produced by a computer-aided design (CAD) system, with no surface detail. The mean naming latencies for the artist set were faster than for the CAD set, though not significantly, with a significant degree of object correlation being observed. However, in certain cases there were significant differences between objects. These were investigated in a further experiment in which subsets with common properties of present or absent surface detail were selected from the artist-drawn stimuli. It was found that the presence of surface features resulted in lower response latencies even for those objects that intuitively could be recognized by parts alone. The time to name photographic and line-drawn stimuli was compared, and a progressive decrease in naming latency from line to monochrome to color stimuli was observed. In a verification task, no significant advantage for color or monochrome photographs over line drawings was found, either when comparing stimuli of equivalent or of different mode. However, there was a tendency for the comparison of different modes to take longer than the comparison of same modes. The results are discussed in terms of theories of human visual processing and cognitive and computational models of object recognition.     

User-controlled photographic animations, photograph-based questions, and questionnaires: Three Internet-based instruments for measuring drivers’ risk-taking behavior

The Internet has been exploited successfully in the past as a medium for behavioral research. This paper presents a series of studies designed to assess Internet-based measures of drivers’ risk-taking behavior. First, we compared responses from an Internet sample with a traditional pencil-and-paper sample using established questionnaire measures of risk taking. No significant differences were found. Second, we assessed the validity of new Internet-based instruments, involving photographs and photographic animations, that measured speed, gap acceptance, and passing. Responses were found to reflect known demographic patterns of actual behavior to some degree. Also, a roadside survey of speeds was carried out at the locations depicted in the photographic measure of speeding and, with certain exceptions, differences between the two appeared to be constant. Third, a between-subject experimental manipulation involving the photographic animation measure of gap acceptance was used to demonstrate one application of these techniques.