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PubMed1991

Does primate motion perception depend on the magnocellular pathway?

This study examined the importance of the primate magnocellular retinocortical pathway in the perception of moving stimuli. A portion of the magnocellular pathway was permanently and selectively interrupted by ibotenic acid injections in the LGN of macaque monkeys. We then tested contrast sensitivity for detecting moving stimuli, as well as two indices of motion perception, contrast sensitivity for opposite direction discrimination and speed difference thresholds, in the affected portion of the visual field. Magnocellular lesions greatly reduced detection contrast sensitivity at high temporal and low spatial frequencies and had a similar effect on contrast sensitivity for opposite direction discrimination under these same stimulus conditions. Consequently, opposite direction discriminations could be made at contrast threshold, suggesting that magnocellular lesions reduced the visibility of stimuli used to test direction perception, but did not act directly on direction perception. Magnocellular lesions also elevated speed difference thresholds under some stimulus conditions. However, this deficit was reduced or eliminated by raising the contrast of the test stimulus. Together, these findings suggest that magnocellular lesions reduce the visibility of stimuli used to test motion perception but that they do not appear to alter motion perception otherwise.

Animals↗

PubMed1990

Muscle activities in the hand and arm during tooth brushing and the regulation of brushing movements by oral sensory perception.

Investigations were made of the forces during brushing of the teeth, the patterns of brushing movements, and muscle activities, with and without blockage of sensory perception in the oral cavity, while each subject brushed by the rolling method, scrubbing method, and by his own individual habitual brushing method. We learned from electromyograms that the scrubbing method primarily used the muscles of the palm of the hand and the forearm, while the rolling method cleaned principally by action of the muscles of the upper arm and shoulder. With the rolling method, the rhythmic pattern of the brushing movement and muscle activity were lost when sensory perception in the oral cavity was blocked and, in those subjects who had a low periodontal membrane tactile threshold, the brushing force was greater than when sensory perception was not blocked. However, no effect was observed with blockage of the sensory perception in the oral cavity when the scrubbing method was used. Since brushing movements with the scrubbing method resemble the movements of writing, we also carried out investigations on the relationship between the forces during writing and brushing. As a result we found that with the scrubbing method, the brushing forces were strong for the subjects who had strong writing forces, while they were weak for those with weak writing forces. It was clear from the above results that the force of brushing with the rolling method was affected more by factors relating to oral sensory perception than muscle activity, while with the scrubbing method it was affected more by factors relating to muscle activity of the palm of the hand and forearm than by oral sensory perception. There was a clear difference in the brushing forces, pattern of brushing movements, and muscle activity between experienced and inexperienced subjects with both the scrubbing and rolling methods. Thus we learned that the effect of brushing instructions could be evaluated not only by the efficiency of plaque removal, brushing force or skill of brushing movements, but also by muscle activity. The phenomena observed with the scrubbing and rolling methods were not seen with the subjects' individual habitual brushing method.

Adult↗

PubMedDate not supplied

Perception of parents' behavior and children's general fearfulness.

A study was conducted to investigate the relationship between perception of parents' support, punishment, control, and encouragement of autonomy and general fearfulness in ten- to eleven-year-old girls. Subjects included 68 girls in the fifth and sixth grades. The Cornell Parent Behavior Description Questionnaire was used as a measure of the girls' perception of their parents' support, punishment, control, and autonomy-granting. Geer's Fear Survey Schedule II-Modified was used as a measure of the girls' general fearfulness. A low significant positive correlation (r = 0.215) between the girls' perception of their parents' punishment and the girls' general fearfulness was observed. Also observed were: a low significant negative correlation (r = -0.201) between the girls' perception of their parents' encouragement of autonomy and the girls' general fearfulness and, contrary to expectation, a slight negative correlation (r = 0.173) between the girls' perception of their parents' support and the girl's general fearfulness. A slight negative correlation (r = -0.109) appeared between the girls' perception of their parents' control and the girls' general fearfulness. An auxiliary finding was that the girls perceived their mothers as more supportive, punitive, and controlling than their fathers. Upper middle-class parents were viewed by their daughters as less punitive and more autonomy-granting than lower middle-class parents.

Anxiety↗

PubMed1980

The family perceptions of delinquents, high school students, and freshman college students.

The family perceptions of 46 delinquents, 52 high school students, and 46 freshman college students were measured through the use of a shortened version of the Family Concept Test. Each subject's perceptions of his or her level of rebelliousness toward parents, parental marital relations, and parental discipline were also measured. Results showed that the delinquents had more negative family perceptions as compared to the high school and college students. However, subjects in all three groups who perceived themselves as rebellious had similar negative family perceptions. Delinquents and college students, but not high school students, had similar negative family perceptions when they viewed their parents' marriage as unhappy. These data show that delinquents and nondelinquents tend to have similar negative family perceptions when they perceive themselves as rebellious and their parents as unhappy.

Adaptation, Psychological↗

PubMed1996

[Time perception, maternal tasks, and maternal role behavior among pregnant Japanese women].

The relationship of time perception, maternal tasks, and maternal role behavior was examined in 140 pregnant Japanese women with a short-term longitudinal design. A model developed by Rubin provided the conceptual framework for this research. The Time Perception Scale. Time Production Method, and the Prefatory Maternal Response measured the study variables. Study results revealed significant differences in duration of time, time production, maternal-fetal attachment, and maternal role behavior before and after quickening(fetal movement)occurred. Medium to strong positive relationships among time orientation, maternal-fetal attachment, gratification, and maternal role behavior were found before and after movement. After quickening, a weak relationship between time orientation and duration was found. After controlling maternal-fetal attachment and gratification in pregnancy and maternal role, orientation in time perception accounted for significant amounts of variance in maternal role behavior before and after fetal movement. Results show that the process of becoming a mother, which started before quickening, increased in magnitude after fetal movement. The function of fetal movement is important in developing motherhood. In the process of becoming a mother, cognitive, emotional, and behavioral aspects in becoming a mother are inseparable from each other. Future orientation of time perception contributes to development of maternal role behavior. Having a future orientation during pregnancy may indicate hope or positive expectation. Based on these findings, several recommendations were proposed: (a)to study further the general process of becoming a mother and the role of time perception in developing motherhood, (b)to disseminate information to the general public about the process in development of motherhood, (c)to construct theory to explain the process of becoming a mother, and(d)to conduct future research to clarify the construct of time perception and attachment.

Adult↗

PubMed1997

Pharmacological modulation of rectal tone alters perception of distention in humans.

OBJECTIVE: Drugs can alter perception of balloon distention of the GI tract. It has been proposed that the mechanism by which this occurs is through effects on visceral afferent pathways. Our hypothesis was that modulation of rectal tone will also influence the perception of rectal balloon distention. METHODS: Fasting and postprandial rectal tone, compliance, and perception of rectal distention were measured in 25 healthy subjects, using a five-armed, parallel, single-blinded study design. Each subject received either glucagon, nitroglycerin, clonidine, yohimbine, or saline. RESULTS: Rectal tone, but not compliance, influenced perception as measured by balloon distention of the rectum (r = 0.6, p = 0.002). Glucagon, nitroglycerin, and clonidine reduced and yohimbine increased fasting tone compared with saline. Compliance and postprandial tone were similar in all groups. Yohimbine increased rectal perception of distention. CONCLUSIONS: Tone is one of the factors that influences the sensory perception of balloon distention in the human rectum. Alpha2-adrenergic agents, a nitric oxide donor, and glucagon altered fasting rectal tone, but postprandial tone was similar after administration of each agent.

Adult↗

PubMed2006

Electrical brain imaging reveals spatio-temporal dynamics of timbre perception in humans.

Timbre is a major attribute of sound perception and a key feature for the identification of sound quality. Here, we present event-related brain potentials (ERPs) obtained from sixteen healthy individuals while they discriminated complex instrumental tones (piano, trumpet, and violin) or simple sine wave tones that lack the principal features of timbre. Data analysis yielded enhanced N1 and P2 responses to instrumental tones relative to sine wave tones. Furthermore, we applied an electrical brain imaging approach using low-resolution electromagnetic tomography (LORETA) to estimate the neural sources of N1/P2 responses. Separate significance tests of instrumental vs. sine wave tones for N1 and P2 revealed distinct regions as principally governing timbre perception. In an initial stage (N1), timbre perception recruits left and right (peri-)auditory fields with an activity maximum over the right posterior Sylvian fissure (SF) and the posterior cingulate (PCC) territory. In the subsequent stage (P2), we uncovered enhanced activity in the vicinity of the entire cingulate gyrus. The involvement of extra-auditory areas in timbre perception may imply the presence of a highly associative processing level which might be generally related to musical sensations and integrates widespread medial areas of the human cortex. In summary, our results demonstrate spatio-temporally distinct stages in timbre perception which not only involve bilateral parts of the peri-auditory cortex but also medially situated regions of the human brain associated with emotional and auditory imagery functions.

Acoustic Stimulation↗

PubMed2005

Laminar cortical dynamics of 3D surface perception: stratification, transparency, and neon color spreading.

The 3D LAMINART neural model is developed to explain how the visual cortex gives rise to 3D percepts of stratification, transparency, and neon color spreading in response to 2D pictures and 3D scenes. Such percepts are sensitive to whether contiguous image regions have the same contrast polarity and ocularity. The model predicts how like-polarity competition at V1 simple cells in layer 4 may cause these percepts when it interacts with other boundary and surface processes in V1, V2, and V4. The model also explains how: the Metelli Rules cause transparent percepts, bistable transparency percepts arise, and attention influences transparency reversal.

Color Perception↗

PubMed1997

The perception of motion and structure in structure-from-motion: comparisons of affine and Euclidean formulations.

I investigated the discrimination of rigid from nonrigid structure and the perception of affine stretches along the line of sight [Norman & Todd (1993). Perception and Psychophysics, 53, pp. 279-291]. Investigations of performance at discriminating rigid from nonrigid structure showed that performance improved when number of views and amount of simulated three-dimensional nonrigidity increased. Investigations of rotations about the vertical which include affine stretches along the line of sight compared Euclidean interpretations of affine-stretching stimuli to human perception. These Euclidean interpretations were obtained from a simple algorithm which recovered structure and motion from this limited class of stimuli under the assumption that distances to the axis of rotation did not change. The algorithm predicted that stretches along the line of sight would be perceived as nearly rigid and have variable angular velocity. These predictions were supported by subjects' reports of occurrences of nonrigidity and minima of angular velocity. The Euclidean algorithm also provided measures of nonrigidity and motion coherence, and experimental results were consistent with a prediction of when perception of nonrigidity would be independent of perception of coherence. The results are discussed relative to the advantages and shortcomings of both the affine and Euclidean approaches to structure-from-motion.

Algorithms↗

PubMed1979

Auditory-visual perception of speech with reduced optical clarity.

Optical cues for visual and auditory-visual (A-V) perception of speech were varied by placing a sheet of rough-surfaced Plexiglas between talker and lipreader and systematically changing the distance between Plexiglas and talker. This distorts the optical environment in a way that is analogous to masking or filtering in the acoustic domain. In studies with normal-hearing adults and with hearing-impaired children, speech (words, sentences) was presented live under different degrees of optical distortion, and observers attempted to identify the stimuli. Visual-along (lipreading) scores dropped abruptly to the chance level as Plexiglas distance (blurring) was increased. A-V scores were relatively high for clear conditions but diminished gradually as Plexiglas distance (blurring) was increased. Under extremely poor optical conditions, A-V scores reached a plateau. This represents essentially auditory perception without meaningful optical cues for speech. Results parallel those of previous acoustic studies that compared auditory with A-V perception of speech as a function of S/N ratio or sensation level, demonstrating a reciprocal aspect of optical and acoustic cues for speech perception. Optical distortion seems to have potential as an auditory training technique to shift attention of hearing-impaired observers to non-dominant acoustic cues during A-V perception of speech.

Adolescent↗

PubMed2006

The influence of biological motion perception on structure-from-motion interpretations at different speeds.

Nonrigid point-light representations of biological motion are ideal to test higher level influences on structure-from-motion (SFM) perception. Here, we investigated the influence of biological motion perception on 3D SFM interpretations at different speeds. We presented nonrigid biological motion and rigid structures rotating around the vertical axis. The familiarity of the stimuli was changed by presenting three walker types: normal, inverted, and phase scrambled. Subjects had to discriminate rotation in depth and rigidity. We found that at lower-than-natural gait speeds, subjects perceived nonrigid biological motion to be rotating in depth, especially when the walker type was less familiar. In contrast, the percept of rigidity was correct at all speeds. A second experiment, in which a constant fraction of the gait cycle was presented, confirmed the influence of speed and additionally showed that brief displays of a familiar form at a high speed facilitate biological motion interpretations. The more veridical percept of rotation toward higher speeds fits the idea of biological motion channels tuned to higher-more natural walking-speeds that overrule a default assumption to perceive trajectories in depth. We also speculate that the rotation-in-depth percept at lower speeds points toward the existence of low-speed-tuned object motion channels.

Depth Perception↗

PubMed2004

Music perception with cochlear implants: a review.

The acceptance of cochlear implantation as an effective and safe treatment for deafness has increased steadily over the past quarter century. The earliest devices were the first implanted prostheses found to be successful in compensating partially for lost sensory function by direct electrical stimulation of nerves. Initially, the main intention was to provide limited auditory sensations to people with profound or total sensorineural hearing impairment in both ears. Although the first cochlear implants aimed to provide patients with little more than awareness of environmental sounds and some cues to assist visual speech-reading, the technology has advanced rapidly. Currently, most people with modern cochlear implant systems can understand speech using the device alone, at least in favorable listening conditions. In recent years, an increasing research effort has been directed towards implant users' perception of nonspeech sounds, especially music. This paper reviews that research, discusses the published experimental results in terms of both psychophysical observations and device function, and concludes with some practical suggestions about how perception of music might be enhanced for implant recipients in the future. The most significant findings of past research are: (1) On average, implant users perceive rhythm about as well as listeners with normal hearing; (2) Even with technically sophisticated multiple-channel sound processors, recognition of melodies, especially without rhythmic or verbal cues, is poor, with performance at little better than chance levels for many implant users; (3) Perception of timbre, which is usually evaluated by experimental procedures that require subjects to identify musical instrument sounds, is generally unsatisfactory; (4) Implant users tend to rate the quality of musical sounds as less pleasant than listeners with normal hearing; (5) Auditory training programs that have been devised specifically to provide implant users with structured musical listening experience may improve the subjective acceptability of music that is heard through a prosthesis; (6) Pitch perception might be improved by designing innovative sound processors that use both temporal and spatial patterns of electric stimulation more effectively and precisely to overcome the inherent limitations of signal coding in existing implant systems; (7) For the growing population of implant recipients who have usable acoustic hearing, at least for low-frequency sounds, perception of music is likely to be much better with combined acoustic and electric stimulation than is typical for deaf people who rely solely on the hearing provided by their prostheses.

Audiometry↗

PubMed2002

Neural correlates of structure-from-motion perception in macaque V1 and MT.

Structure-from-motion (SFM) is the perception of three-dimensional shape from motion cues. We used a bistable SFM stimulus, which can be perceived in one of two different ways, to study how neural activity in cortical areas V1 and MT is related to SFM perception. Monkeys performed a depth-order task, where they indicated in which direction the front surface of a rotating SFM cylinder display was moving. To prevent contamination of the neural data because of eye position effects, all experiments with significant effects of radius, vergence, and velocity were excluded. As expected, the activity of approximately 50% of neurons in V1 and approximately 80% of neurons in MT is affected by the stimulus. Furthermore, the activity of 20% of neurons in area V1 is modulated with the percept. This proportion is higher in MT, where the activity of >60% of neurons is modulated with the percept. In both areas, this perceptual modulation occurs only in neurons with activity that is also affected by the stimulus. The perceptual modulation is not correlated with neural tuning properties in area V1, but it is in area MT. Together, these results suggest that V1 is not directly involved in the generation of the SFM percept, whereas MT is. The perceptual modulation in V1 may be attributable to top-down feedback from MT.

Action Potentials↗

PubMed2006

Subjective visual horizontal in the upright posture and asymmetry in roll-tilt perception: independent measures of vestibular function.

The subjective visual horizontal (SVH) was measured in the upright position and at 10, 20, and 30 degrees of head and body tilt to the right and left. Normal subjects (n=25) were tested on two separate occasions with an interval of 1-14 days. Test variables considered were the SVH in the upright position, the perception of tilt to the right and left, calculated on the basis of the SVH in the upright and tilted positions, and the asymmetry in tilt perception. There was no correlation between the perception of tilt to the right and to the left r=0.10). Neither was there any correlation between the SVH in the upright position, representing a resting asymmetry, and the asymmetry in tilt perception, i.e. the response asymmetry (r=0.17). However, for each variable, there was a high correspondence between data obtained at test and retest (r ranged from 0.68 to 0.89, p<0.001), suggesting that the independence between variables is not due to noise. Findings are discussed taking into consideration the possible roles of otoliths and semicircular canals in the formation of the SVH. In an attempt to explain the independence between the two measures of asymmetry it is hypothesized that while the otoliths must be essential for the perception of static lateral tilt, the SVH in the upright position to a considerable degree reflects semicircular canal function.

Adult↗

PubMedDate not supplied

Racial and ethnic disparities in perceptions of physician style and trust.

CONTEXT: While pervasive racial and ethnic inequalities in access to care and health status have been documented, potential underlying causes, such as patients' perceptions of their physicians, have not been explored as thoroughly. OBJECTIVE: To assess whether a person's race or ethnicity is associated with low trust in the physician. DESIGN, SETTING, AND PARTICIPANTS: Data were obtained from the 1996 through 1997 Community Tracking Survey, a nationally representative sample. Adults who identified a physician as their regular provider and had at least 1 physician visit in the preceding 12 months were included (N = 32,929). MAIN OUTCOME MEASURE: Patients' ratings of their satisfaction with the style of their physician and their trust in physicians. The Satisfaction With Physician Style Scale measured respondents' perceptions of their physicians' listening skills, explanations, and thoroughness. The Trust in Physician Scale measured respondents' perceptions that their physicians placed the patients' needs above other considerations, referred the patient when needed, performed unnecessary tests or procedures, and were influenced by insurance rules. RESULTS: After adjustment for socioeconomic and other factors, minority group members reported less positive perceptions of physicians than whites on these 2 conceptually distinct scales. Minority group members who lacked physician continuity on repeat clinic visits reported even less positive perceptions of their physicians on these 2 scales than whites. CONCLUSIONS: Patients from racial and ethnic minority groups have less positive perceptions of their physicians on at least 2 important dimensions. The reasons for these differences should be explored and addressed. Arch Fam Med. 2000;9:1156-1163

Adolescent↗

PubMed1998

Correlates of hospitalized patients' perceptions of service quality.

The purpose of this study was to examine hospital patients' perceptions of service quality in relation to four independent variables: (a) nurses' perceptions of human resource practices, (b) nurses' perceptions of autonomy in practice, (c) patient satisfaction with nursing care, and (d) patients' perceptions of organizational climate for service. The sample consisted of 102 nurse-patient dyads in an acute care hospital. Patients responded to the Modified Health Care Service Performance Instrument, the revised LaMonica-Oberst Patient Satisfaction Scale, and the Organizational Climate for Service Semantic Differential. Nurses responded to the Employee Turnover Diagnostic and the Dempster Practice Behaviors Scale. Two of the four correlational hypotheses were supported. Patient satisfaction with nursing care and patients' perceptions of organizational climate for service were each positively related to patients' perceptions of service quality. A multivariate regression hypothesis was not supported. Failure to support two theoretically based correlational hypotheses may be related to methodological problems experienced with dyadic research.

Adult↗

PubMed2000

Volume perception in parkinsonian speech.

This study contrasted the volume level of speech production with perceived volume. Fifteen idiopathic patients with Parkinson's disease who have hypophonic dysarthria and 15 healthy age- and sex-matched control subjects participated in this study. Testing took place in a sound-proof room. Ability to regulate volume was tested at three instructional levels of loudness: participants were given no instructions regarding volume (to elicit normal default volume) or were asked to read loudly or quietly. Two types of volume-perception judgments were made. First, an estimate of one's own volume, immediately after speaking (that is, immediate perception), and secondly, an estimation of reading volume after hearing one's own voice played back (that is, playback perception). These perceptual ratings were compared with actual speech volume produced in reading and conversation tasks. It was found that there was less of a difference between patients' production and perception of speech volume compared with that of the control subjects. While patients spoke more quietly than control subjects, they nevertheless perceived (immediate and playback perception) their own speech to be louder than did the control subjects. Patients overestimated the volume of their speech during both reading and conversation. The findings raise the question as to whether impaired speech production is driven by a basic perceptual fault or whether perception is abnormal as a consequence of impaired mechanisms involved in the generation of quiet speech.

Aged↗

PubMed2004

Interactive on-line continuing medical education: physicians' perceptions and experiences.

INTRODUCTION: Although research in continuing medical education (CME) demonstrates positive outcomes of on-line CME programs, the effectiveness of and learners' satisfaction with interpersonal interaction in on-line CME are lower Defined as faculty-learner or learner-learner interpersonal interaction, this study explores physicians' perceptions of and experiences in interactive on-line CME and factors influencing these. METHODS: Focus groups and interviews were undertaken by three Canadian universities. Using purposive sampling, we recruited physicians based on their experiences with interactive on-line CME. Content analysis was applied first, followed by a comparative analysis to confirm themes and findings. RESULTS: Physicians based their perceptions of interactive on-line CME by comparing it with what they know best, face-to-face CME. Although perceptions about access and technical competency remained important, two other themes emerged. The first was the capacity of on-line CME to meet individual learning preferences, which, in turn, was influenced by the quality of the program, the degree of self-pacing or self-direction, opportunity for reflection, and educational design. The second was the quality and quantity of interpersonal interaction, which was shaped by perceptions of social comfort, the educational value of interactions, and the role of the facilitator. Prior experience with on-line CME moderated perceptions. DISCUSSION: The extent that on-line CME programs reflected characteristics of high-quality CME and individual learning preferences appeared to shape perceptions about it. It is important to incorporate the characteristics of effective CME into the design and implementation of interactive on-line programs, considering diverse learning preferences, providing faculty development for on-line facilitators, and grounding this work in learning theory.

Attitude of Health Personnel↗