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At least 811 records · Page 45Linked to original sources

PubMed1985

Influence of safety belt usage on perception of the risk of an accident.

Does the use of a safety belt increase or decrease the perception of the risk of an accident? Young and older male drivers were asked to drive an urban route and rate their perceptions of the risk of an accident. On the first driving trip all subjects were unbelted, while on the second driving trip half of the subjects wore a safety belt while half did not. Results indicated that young male drivers decrease their perception of the risk of an accident as they become familiar with a driving route if they are NOT wearing a safety belt. Young male drivers asked to wear a safety belt sustained their perception of the risk of an accident as they became familiar with the test route. Older drivers' perception of the risk of an accident was not affected by familiarity or safety belt usage.

Accidents, Traffic↗

PubMed1994

Somatic stimulation reduces perception of gut distention in humans.

BACKGROUND/AIMS: Perception of gut symptoms may depend on visceral sensory modulation, but the mechanisms are poorly understood. Based on somatosensory data, we hypothesized that somatic stimulation modulates perception of gut stimuli. METHODS: Perception and gut reflexes were measured in 8 healthy subjects in response to increasing gastric and duodenal distentions (stimulus-response trials) performed alone or with simultaneous application on the hand of either low (just perceivable) or high (nonpainful) transcutaneous electrical nerve stimulation (100 Hz, 100 microseconds). Fixed pressure distentions were performed in stepwise increments by gastric and duodenal barostats to determine the respective thresholds for discomfort. Perception was measured by a questionnaire, and gut reflex responses were measured as isobaric volume changes by the barostats. Individual stimuli of 2 minutes' duration were randomly applied at 10-minute intervals. RESULTS: Somatic stimuli increased the tolerance to gut distention, and this effect was more pronounced with high stimuli. The gastric threshold for discomfort was 7.3 +/- 0.5 mm Hg with high stimuli vs. 5.5 +/- 0.2 mm Hg without stimuli, and the duodenal discomfort threshold was 15.5 +/- 1.5 mm Hg with high stimuli vs. 13.5 +/- 1.4 mm Hg without stimuli; P < 0.05 for both. Somatic stimuli modified neither basal gut tone nor the relaxatory duodenogastric reflex induced by duodenal distention (gastric expansion by 203 +/- 48 mL with high stimuli and 208 +/- 73 mL without stimuli). CONCLUSIONS: Somatic stimulation reduces perception of gut distention without interfering with local and reflex gut responses.

Adult↗

PubMed1986

Developmental changes in visual and auditory contributions to speech perception.

Previous research has demonstrated that listeners make use of both auditory and visual information in bimodal speech perception. Preschool children appear to evaluate and integrate the two sources of information in the same manner as adults, but the children are less influenced by the visual source. The current experiments test a possible explanation of this difference and extend the question to younger children. It is possible that children are poorer lip-readers than adults and thus have less complete information about the visual source. Children and adults were tested with both auditory and visual sources and were also required to identify speech events on the basis of only the visual source. In addition to replicating the previous findings in the bimodal situation, the current experiments found that children are poorer lip-readers than adults. Furthermore, a positive correlation was observed between lip-reading ability and the size of the visual contribution to bimodal speech perception. A fuzzy logical model of speech perception provided a good quantitative description of the results even with the assumption that the visual information was equivalent in both the bimodal and lip-reading conditions. The results also contradict the categorical perception of speech events and any nonindependence in the evaluation of auditory and visual information in speech perception.

Adolescent↗

PubMed1983

To perceive is to doubt: the relativity of perception.

The uncertainty or entropy theory of perception is founded on the premise that for perception to occur, there must first of all be uncertainty. That is, perception or awareness is relative to the expectation of the perceiver. This view of perception leads to a seeming-paradox. How can there be uncertainty unless the alternatives have previously been perceived? But, by the premise of the theory, how can the alternatives have been perceived unless there was prior uncertainty? It is shown that this paradox may result physiologically in the concurrence of sensory and motor (or "active") events during the process of perceiving. It is shown, further, that a close analogy exists between systems of formal logic and systems which perceive through uncertainty. This, in turn, suggests a basis for a calculus of perception.

Humans↗

PubMed1983

Three-dimensional perception of radiographic images among dental students and dentists.

Six radiographs exhibiting problems of three-dimensional perception were shown to seventy-six inexperienced dental students and to seventy-six experienced dentists. They were asked (1) from which viewing direction they perceived the image, (2) if they were able to reverse the image, and if not (3) if they denied the possibility of reversibility. In most cases a vast majority (83 to 93 percent) agreed in one perception. Twelve to 62 percent were unable to reverse the images. High percentages of the observers denied perceptions other than their own. No statistically significant differences were observed between the answers of the students and the dentists. The decisions of the observers and their restricted ability for ambiguous perception are discussed. Rules governing the choices of perception are suggested. The importance of training at undergraduate as well as postgraduate levels in perceiving radiographic images ambiguously and three-dimensionally is stressed.

Dentists↗

PubMedDate not supplied

Heart rate perception and the voluntary control of heart rate.

Heart rate perception was assessed in two sets of trials by having subjects set an intermittent visual pulse to match their heart rates. Just prior to matching subjects were required to either hyperventilate, hypoventilate or breathe normally to encourage a range of cardiac levels. Preceding each set of perception trials, bidirectional heart rate control was attempted. While one group of subjects received no exteroceptive feedback throughout, the other received continuous visual heart rate feedback on the second occasion. The data provided evidence of heart rate perception (as indexed by the correlation between interbeat and interpulse intervals) in a substantial number of instances. Further, perception was reliably associated with initial externally unaided cardiac control, although only in the increase direction. However, while the introduction of feedback tended to enhance cardiac control albeit only acceleratory control, no parallel effect was observed for perception. Analysis of interbeat and interpulse intervals in the different conditions of the matching task suggested that a real discrimination was probed by the procedure employed, but implied that respiratory cues afforded the basis for discrimination.

Adolescent↗

PubMed1996

Visceral perception, anhedonia, and emotion.

Few investigators have attempted to examine empirically the relationship between perception of autonomic arousal and emotional state. According to Jamesian theory, individuals who are more aware of their visceral activity should demonstrate greater affective response to emotion-laden stimuli than individuals who are not viscerally perceptive. Therefore, certain groups of 'unemotional' subjects, such as anhedonics, may report fewer or less intense emotional experiences due to an attenuation or lack of autonomic feedback. Results from studies by Katkin (Psychophysiology, 22, (1985) 125-137) suggest that there is a relationship between induced sympathetic arousal, the perception of that arousal, and the self-report of emotional experience. The present study sought to expand upon these findings by comparing visceral perception (i.e. heartbeat detection) performance and a multi-component assessment of emotion in normal and anhedonic subjects. No correlation was found between anhedonia and visceral perception; however, anhedonics were significantly different from normals across several measures of heart rate, self-report, and facial expressions in response to emotion-eliciting slides, with anhedonics consistently showing emotional hypo-responsiveness. Additionally, subjects who were able to perceive their own heartbeats were found to be more facially expressive than poor perceivers.

Adolescent↗

PubMed1987

Diffuse noxious inhibitory controls (DNICs): psychophysical evidence in man for intersegmental suppression of noxious heat perception by cold pressor pain.

Counterirritation, the phenomenon of one painful stimulus reducing pain caused by a second noxious stimulus, has been recognized clinically for decades. Recently a physiological mechanism to explain counterirritation was described and termed diffuse noxious inhibitory controls (DNICs). Nevertheless, few psychophysical studies have examined systematically the effects of a noxious conditioning stimulus on pain perception. The present study examined the perception of painful heat stimuli on the face before, during and after the subject submerged a hand in painfully cold water (5 degrees C) for 5 min (cold pressor pain). We found that the subjects' ratings of the heat stimuli were significantly, although not completely, reduced during the cold pressor pain; this attenuation of pain perception continued after the noxious conditioning stimulus was withdrawn. Similarly, the pain threshold was significantly increased from 45.7 degrees C to 47.3 degrees C while the hand was in cold water and this threshold remained elevated after the cold water was terminated. Since DNICs have been found to completely and selectively inhibit the activity of only one type of pain transmission neuron (wide dynamic range), our data suggest that these neurons are involved in the perception of pain intensity. However, the persistence of residual pain perception in the presence of noxious conditioning stimuli indicates the importance of other nociceptive pathways.

Adult↗

PubMed1993

Ethnocultural influences on variation in chronic pain perception.

In multiple studies cultural affiliation has been found to have an important influence on perception of and response to experimental and acute pain. Despite that evidence little work has been directed to understanding the cultural dimensions of the chronic pain experience. We present the results of a quantitative study of reported chronic pain perception in 372 chronic pain patients in six ethnic groups, who were under treatment at a multidisciplinary pain-management center. The role of ethnic and cultural experiences in the complex array of physical, cultural, psychological and social factors which influence the chronic pain experience is identified. Ethnocultural affiliation is important to chronic pain perception and response variation. In this study population the best predictors of pain intensity variation are ethnic group affiliation and locus of control (LOC) style (ethnic group identity is also a predictor of LOC style). It appears that pain intensity variation may be affected by differences in attitudes, beliefs and emotional and psychological states associated with the different ethnic groups. This study suggests a biocultural model may be useful in conceptualizing the complex interaction of biological, cultural and psychosocial factors in the process of human pain perception. Although it is likely that intense pain affects attitudes and emotions, it is also very likely that attitudes and emotions influence reported perceptions of pain intensity. Pain intensity variation in this study population is not significantly associated with diagnosis, present medication types, or types of past treatments or surgeries for pain.

Adult↗

PubMed1994

Effects of experimental and clinical noxious counterirritants on pain perception.

It is commonly accepted that application of a sustained noxious stimulus frequently suppresses the perception of pain. In this investigation, we have determined whether painful forearm ischemia suppresses tooth pain resulting from an acute irreversible pulpitis. We have also determined whether the physiological responses to toothache alter the perception of pain evoked by experimental procedures. Ten male subjects experiencing a painful toothache (group TA) and 7 age-matched pain-free male subjects (group PF) participated in these studies. During session 1, heat pain threshold and tolerance values were determined for both groups. The times to ischemic pain onset and ischemic pain tolerance were determined for both groups using the submaximal effort tourniquet procedure. The effect of the tourniquet procedure on the intensity, unpleasantness, and spatial distribution of toothache was also assessed. Session 2 was conducted on 7 TA and 7 PF subjects 1 week later and was conducted like session 1 with the exception that group TA was not experiencing tooth pain during this session. Measures of thermal pain perception and forearm ischemic pain perception were not altered by the occurrence of toothache. In contrast, sustained noxious forearm ischemia produced a marked reduction in the intensity, unpleasantness and spatial distribution of pulpal pain. These effects on pulpal pain remained for at least 5 min after removal of the tourniquet while the arm was pain free. These findings suggest that a noxious conditioning stimulus does not universally inhibit pain perception but instead depends on unidentified interactions between the noxious test and conditioning stimuli.

Acute Disease↗

PubMed1982

Drug counselors' perceptions of clients: demographic, personality and psychopathology correlates.

Counselors' interpersonal perceptions of their clients in outpatient drug treatment were studied. Factor analysis produced three general factors, interpreted as perceptions of manageability, treatment readiness, and suitability for group treatment. Counselor perception of client interpersonal attractiveness did not emerge as a separate factor, but appeared equally significantly related to each of the first two factors. Correlates of counselor perceptions were sought among measures of client program performance, demographic and drug use history, psychopathology, and counselor background and personality. With one exception, measures of clients' actual program performance were the best predictors of counselors' perceptions of clients. Clinical implications are discussed.

Adult↗

PubMed1991

Auditory image perception and analysis: the basis for hearing.

The premise of this paper is that the auditory system's primary function is its ability to determine the sources of sound. Auditory image perception and analysis are defined as the basis for sound source determination. Few studies in the literature have focused on understanding these abilities and the paper argues that more attention should be paid to auditory image perception and analysis. Four questions are posed for understanding auditory image formation and seven physical variables are described which might be used for auditory image perception. The paper relates auditory image perception and analysis to a number of other topics in the hearing sciences in order to reinforce the argument that auditory image perception and analysis are the basis of hearing.

Acoustic Stimulation↗

PubMed2005

A comparative assessment of the perception of Chinese facial profile esthetics.

INTRODUCTION: The aim of this study was to compare the perception of male and female Chinese facial profile esthetics between dental professionals, dental students, and laypersons. MATERIAL: The sample comprised 31 dental professionals (20 orthodontists, 11 oral surgeons), 92 dental students, and 152 laypersons in an Asian community. The facial profile photographs and lateral cephalometric radiographs of a Chinese man and a woman, each with a normal profile, a Class I incisor relationship, and a Class I skeletal pattern, were digitized. The digital images were modified to obtain 7 facial profiles for each sex. The images were constructed by altering cephalometric skeletal and dental hard tissue Chinese normative values by 2 standard deviations in the anteroposterior plane only. The 7 profiles were (1) bimaxillary protrusion, (2) protrusive mandible, (3) retrusive mandible, (4) normal profile (Class I incisor with Class I skeletal pattern), (5) retrusive maxilla, (6) protrusive maxilla, and (7) bimaxillary retrusion. RESULTS: Normal and bimaxillary retrusion Chinese male and female profiles were perceived to be highly attractive by all 3 groups. Profiles with a protrusive mandible were perceived to be the least attractive. Dental professionals, dental students, and laypersons were highly correlated for the perception of male (r > 0.67) and female (r > 0.93) profile esthetics. All correlation coefficients were found to be significant for the perception of female profiles, but, for male profiles, only the correlation coefficient between dental students and laypersons was significant. CONCLUSIONS: Chinese male and female profiles that were normal or had bimaxillary retrusion were perceived to be highly attractive by dental professionals, dental students, and laypersons, and profiles with a protrusive mandible were perceived to be the least attractive. Dental students and laypersons were more tolerant of a male profile with a retrusive mandible than were dental professionals, and all groups were more tolerant of bimaxillary protrusion in women than in men. Dental professionals, dental students, and laypersons had a similar trend in male and female esthetic preferences. The perception of female profiles by all 3 groups was highly and significantly correlated. Only the perception of male esthetics by dental students and laypersons was not significantly correlated with dental professionals.

Adult↗

PubMed2005

A comparison of providers' and consumers' perceptions of facial-profile attractiveness.

INTRODUCTION: The purpose of this study was to evaluate the perception of facial attractiveness in profile digital photographs that were incrementally altered to produce different combinations of mandibular anteroposterior positions and lower anterior facial heights. The specific aims were to determine whether there is concordance between providers and consumers in their perceptions of facial attractiveness, and to evaluate whether interactions of the anteroposterior and vertical dimensions and the magnitude of these interactions influence perception of facial attractiveness. METHODS: Profile digital photographs and cephalograms of 3 men and 3 women were used. The position of the jaw was altered incrementally with Dolphin imaging equipment (Dolphin Imaging and Management, Chatsworth, Calif), and booklets were created. One hundred raters (50 laypersons, 25 oral surgeons, 25 orthodontists) scored the profiles on a visual analog scale. All images were duplicated to test intrarater reliability. Factorial ANOVA with repeated measures and the Tukey-Kramer post-hoc test for multiple comparisons were used to test for differences in facial attractiveness. The level of significance was set at .05 (P = .05) for all analyses. RESULTS: Intrarater reliability was good (ICC = 0.71), and general concordance was found between providers and consumers in their perceptions of facial attractiveness. Interactions of the anteroposterior and vertical dimensions and the magnitude of change in each dimension influence the perception of facial attractiveness. CONCLUSIONS: The results suggest that preferences of facial attractiveness by laypersons, orthodontists, and oral surgeons in central Ohio are generally in agreement. This information might assist clinicians in treatment planning and making recommendations.

Adolescent↗

PubMed2006

Speech perception in preschoolers at family risk for dyslexia: relations with low-level auditory processing and phonological ability.

We tested categorical perception and speech-in-noise perception in a group of five-year-old preschool children genetically at risk for dyslexia, compared to a group of well-matched control children and a group of adults. Both groups of children differed significantly from the adults on all speech measures. Comparing both child groups, the risk group presented a slight but significant deficit in speech-in-noise perception, particularly in the most difficult listening condition. For categorical perception a marginally significant deficit was observed on the discrimination task but not on the identification task. Speech parameters were significantly related to phonological awareness and low-level auditory measures. Results are discussed within the framework of a causal model where low-level auditory problems are hypothesized to result in subtle speech perception problems that might interfere with the development of phonology and reading and spelling ability.

Adult↗

PubMed2006

Role of the calcarine cortex (V1) in perception of visual cues for saccades.

OBJECTIVE: To determine the initial level at which the pathways for cue perception, saccades and antisaccades diverge. METHODS: Two procedures: single pulse transcranial magnetic stimulation (sTMS) over posterior occiput and backward masking were used. A visual cue directed saccades to the left or right, either a pro-saccade (to the side of the cue but beyond it) or an antisaccade, i.e., contraversive saccade. No visual target was presented. RESULTS: Latencies of the two types of saccades did not differ. Focal sTMS applied unilaterally over V1 suppressed both perception of a cue flashed 80-90ms earlier contralaterally (but not ipsilaterally) and the appropriate saccade. Masking at a delay of 100ms abolished the appropriate saccade and cue perception. CONCLUSIONS: V1 is essential for the perception of a flashed cue and for executing appropriate pro- and contraversive saccades. Masking may occur beyond V1, where the pathways for perception and for saccades at least to the next visual processing level start separating. SIGNIFICANCE: VI is needed for rapid, accurate perceptual and motor responses to the crudest (left versus right) cues. It is unlikely that the "where" system can have a major direct input bypassing V1.

Attention↗

PubMed2005

The nature of learned categorical perception effects: a psychophysical approach.

Categorical perception is often cited as a striking example of cognitive influences on perception. However, some evidence suggests the term is a misnomer, with effects based on cognitive not perceptual processing. Here, using a psychophysical approach, we provide evidence consistent with a learned categorical perception effect that is dependent on analysis within the visual processing stream. An improvement in participants' discrimination between grating patterns that they had learned to place in different categories was 'tuned' around the orientation of the patterns experienced during category learning. Thus, here, categorical perception may result from attentionally modulated perceptual learning about diagnostic category features, based upon orientation-selective stages of analysis. This argues strongly that category learning can alter our perception of the world.

Adult↗

PubMed2005

Strength of visual percept generated by famous faces perceived without awareness: effects of affective valence, response latency, and visual field.

Participants who were unable to detect familiarity from masked 17 ms faces (Stone and Valentine, 2004 and Stone and Valentine, in press-b) did report a vague, partial visual percept. Two experiments investigated the relative strength of the visual percept generated by famous and unfamiliar faces, using masked 17 ms exposure. Each trial presented simultaneously a famous and an unfamiliar face, one face in LVF and the other in RVF. In one task, participants responded according to which of the faces generated the stronger visual percept, and in the other task, they attempted an explicit familiarity decision. The relative strength of the visual percept of the famous face compared to the unfamiliar face was moderated by response latency and participants' attitude towards the famous person. There was also an interaction of visual field with response latency, suggesting that the right hemisphere can generate a visual percept differentiating famous from unfamiliar faces more rapidly than the left hemisphere. Participants were at chance in the explicit familiarity decision, confirming the absence of awareness of facial familiarity.

Adult↗