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PubMed1999

A model of consumers' risk perceptions toward recombinant bovine growth hormone (rbGH): the impact of risk characteristics.

This study estimates the effect risk characteristics, described as outrage factors by Hadden, have on consumers' risk perceptions toward the food-related biotechnology, recombinant bovine growth hormone (rbGH). The outrage factors applicable to milk from rbGH treated herds are involuntary risk exposure, unfamiliarity with the product's production process, unnatural product characteristics, lack of trust in regulator's ability to protect consumers in the marketplace, and consumers' inability to distinguish milk from rbGH treated herds compared to milk from untreated herds. An empirical analysis of data from a national survey of household food shoppers reveals that outrage factors mediate risk perceptions. The results support the inclusion of outrage factors into the risk perception model for the rbGH product, as they add significantly to the explanatory power of the model and therefore reduce bias compared to a simpler model of attitudinal and demographic factors. The study indicates that outrage factors which have a significant impact on risk perceptions are the lack of trust in the FDA as a food-related information source, and perceiving no consumer benefits from farmers' use of rbGH. Communication strategies to reduce consumer risk perceptions therefore could utilize agencies perceived as more trustworthy and emphasize the benefits of rbGH use to consumers.

Animals↗

PubMed2002

Perception of aggression, personality disorders and psychiatric morbidity in nursing students.

OBJECTIVE: To determine the relationship between perception of aggression, personality disorders and psychiatric morbidity. METHOD: Ninety nursing students were interviewed. A two-stage transversal analysis was used, the first stage using the Spanish version of the general health questionnaire (GHQ-28), the true-false test of international personality disorders (IPDE) of Loranger, and the perception of aggression scale (POAS) of Jansen. For the second stage we used the Spanish version of the clinical interview schedule (CIS), and the full test of IPDE. RESULTS: Perception of aggression was mainly described as a violent reaction. There were no significant differences in the perception of aggression according to GHQ(+), CIS(+) and IPDE(+). There was a significant relationship between perception of aggression as violent reaction and gender. CONCLUSION: Aggression was perceived by our nursing students as a violent reaction. A significant relationship with gender was observed.

Adult↗

PubMed1976

Frequency perception of individual and group successes as a function of competition, coaction, and isolation.

The frequency perception of successful and unsuccessful outcomes obtained in serial tasks was investigated in two experiments. Subjects were assigned to serial tasks in which the outcome stimuli ("right" and "wrong") immediately followed subjects' responses to each task item. Subjects' perceptual judgment about the number of "rights and wrongs" obtained was requested at the end of the serial task (incidental event perception). In Experiment 1, subjects performing in groups of four were compared with individual performers both in competing and noncompeting (coacting) conditions. In Experiment 2, the influence of verbal communication and competition versus isolation was examined. Significant and predicted differences in frequeency perception were found (a) in group performers as compared with individual performers, (b) in groups with verbal communication as compared with groups without verbal communication, and (c) in competing groups as compared with noncompeting, especially isolated, groups. The frequency perception of success is discussed in the context of impression formation processes, and its impact on person perception and learning is mentioned. A tentative explanation in terms of affective and cognitive processes related to social interaction is submitted.

Communication↗

PubMed1990

Interpersonal perception in a social context.

Interpersonal perception among well-acquainted individuals in a social context was studied. High acquaintance was expected to provide perceivers with a large sample of target behaviors across situations. In turn, memory for acquaintances should be organized by social group and personality characteristics, as predicted by the social context-personality index theory. Differentiation of the target's traits in memory should produce a target effect on perception that is stronger than the perceiver effect. Furthermore, evidence for accuracy, meta-accuracy, independence of self- and other-perception, and reciprocity of affect were anticipated. A social relations analysis of data from a multiple-interaction, reciprocal design was used to study these phenomena. At the individual level, analyses indicated that perceptions of targets were determined primarily by target characteristics and secondarily by perceiver construction of the judgment. Also, perceivers judged targets as targets judged themselves, and targets knew in general how perceivers viewed them. Self- and other-perceptions were largely independent. Surprisingly, we did not observe dyadic meta-accuracy.

Adult↗

PubMed1993

Phonetic coherence in duplex perception: effects of acoustic differences and lexical status.

A modified version of duplex perception was used to investigate the nature of perceptual organization of speech. Ss were asked to identify stimuli in which a third-formant transition was presented to 1 ear and a full syllable (base) was presented to the other ear. Phonetic integration occurred even when the spectral composition or onset frequency of the isolated transition was varied relative to the base. However, when onset asynchronies were added to spectral differences, the isolated transition ceased to contribute to the syllable percept. Lexical status of the eventual phonetic percepts also influenced the phonetic integration of acoustic components into syllable percepts. These results suggest that combinations of low-level acoustic and phonetic differences between components and higher level lexical information interact to influence the grouping of acoustic components into phonetic percepts.

Adult↗

PubMed1980

Information in speech: observations on the perception of [s]-stop clusters.

A series of experiments is reported that investigated the pattern of acoustic information specifying place and manner of stop consonants in medial position after [s]. In both production and perception, information for stop place includes the spectrum of the fricative at offset, the duration of the silent closure interval, the spectral relationship between the frequency of the stop release burst and the following periodically excited formants, and the spectral and temporal characteristics of the first formant transition. Similarly, the information for stop manner includes the duration of silent closure, the frequency of the first formant at the release, the magnitude of the first formant transition, and the proximity of the second and third formants at release. A relationship was shown to exist in perception between the spectral characteristics of the first formant and the duration of the silent closure required to hear a stop. This appears to reciprocate the covariation of these parameters in production across different places of articulation and different vocalic contexts. The existence of perceptual sensitivity to a wide range of the acoustic consequences of production questions the efficacy of accounts of speech perception in terms of the fractionation of the signal into elemental acoustic cues, which are then integrated to yield a phonetic percept. It is argued that it is inappropriate to ascribe a psychological status to cues whose only reality is their operational role as physical parameters whose manipulation can change the phenotic interpretation of a signal. It is suggested that the metric of the information for phonetic perception cannot be that of the cues; rather, a metric should be sought in which acoustic and articulatory dynamics are isomorphic.

Humans↗

PubMed1985

Psychophysical evidence for a shared representational medium for mental images and percepts.

The intuition that imagery is similar to perception has led many psychologists to assume that imaging an object consists of activating some of the same representational structures that are activated during the perception of that object. This assumption was tested by measuring the effects of visual imagery on concurrent visual perception. The experimental task consisted of a two-interval forced-choice detection task (no stimulus identification required) during which the subject imaged a particular stimulus. In Experiment 1, a matching image led to better detection than a nonmatching image. Interactions between imagery and perception imply a common locus of activity, and the content-specific interactions obtained here imply that the common locus consists of representational structures. In Experiment 2, a matching image facilitated perception only when the image and the stimulus were in the same position. This was taken to imply that the shared representational structures occur at an analog level of perceptual representation.

Discrimination Learning↗

PubMed2000

Perceptions of safety at work: a framework for linking safety climate to safety performance, knowledge, and motivation.

Research in the areas of organizational climate and work performance was used to develop a framework for measuring perceptions of safety at work. The framework distinguished perceptions of the work environment from perceptions of performance related to safety. Two studies supported application of the framework to employee perceptions of safety in the workplace. Safety compliance and safety participation were distinguished as separate components of safety-related performance. Perceptions of knowledge about safety and motivation to perform safely influenced individual reports of safety performance and also mediated the link between safety climate and safety performance. Specific dimensions of safety climate were identified and constituted a higher order safety climate factor. The results support conceptualizing safety climate as an antecedent to safety performance in organizations.

Australia↗

PubMed2002

The convergent and discriminant validity of subjective fit perceptions.

This study examined whether employees develop perceptions about 3 different types of fit: person-organization fit, needs-supplies fit, and demands-abilities fit. Confirmatory factor analyses of data from 2 different samples strongly suggested that employees differentiate between these 3 types of fit. Furthermore, results from a longitudinal design of 187 managers supported both the convergent and discriminant validity of the different types of fit perceptions. Specifically, person-organization fit perceptions were related to organization-focused outcomes (e.g., organizational identification, citizenship behaviors, turnover decisions), whereas needs-supplies fit perceptions were related to job- and career-focused outcomes (e.g., job satisfaction, career satisfaction, occupational commitment). Although demands-abilities fit perceptions emerged as a distinct construct, they were not related to hypothesized outcomes (e.g., job performance, raises).

Cross-Sectional Studies↗

PubMed2005

The role of job security in understanding the relationship between employees' perceptions of temporary workers and employees' performance.

On the basis of psychological contract and social cognition theories, the authors explored the role of full-time employees' perceived job security in explaining their reactions to the use of temporary workers by using a sample of 149 full-time employees who worked with temporaries. As hypothesized, employees' perceived job security negatively related to their perceptions that temporaries pose a threat to their jobs, but it did not relate to their perceptions that temporaries are beneficial. Furthermore, employees' job security moderated the relationships between benefit and threat perceptions and supervisor ratings of job performance. For those with high job security, there was a positive relationship between benefit perceptions and performance. For those with low job security, there was a negative relationship between threat perceptions and performance.

Adult↗

PubMed2006

Faces are "spatial"--holistic face perception is supported by low spatial frequencies.

Faces are perceived holistically, a phenomenon best illustrated when the processing of a face feature is affected by the other features. Here, the authors tested the hypothesis that the holistic perception of a face mainly relies on its low spatial frequencies. Holistic face perception was tested in two classical paradigms: the whole-part advantage (Experiment 1) and the composite face effect (Experiments 2-4). Holistic effects were equally large or larger for low-pass filtered faces as compared to full-spectrum faces and significantly larger than for high-pass filtered faces. The disproportionate composite effect found for low-pass filtered faces was not observed when holistic perception was disrupted by inversion (Experiment 3). Experiment 4 showed that the composite face effect was enhanced only for low spatial frequencies, but not for intermediate spatial frequencies known be critical for face recognition. These findings indicate that holistic face perception is largely supported by low spatial frequencies. They also suggest that holistic processing precedes the analysis of local features during face perception.

Adolescent↗

PubMed1992

La langue et les Lèvres: cross-language influences on bimodal speech perception.

Previous research in speech perception has yielded two sets of findings which are brought together in the present study. First, it has been shown that normal hearing listeners use visible as well as acoustical information when processing speech. Second, it has been shown that there is an effect of specific language experience on speech perception such that adults often have difficulty identifying and discriminating non-native phones. The present investigation was designed to extend and combine these two sets of findings. Two studies were conducted using six consonant-vowel syllables (/ba/, /va/, /alpha a/, /da/, /3a/, and /ga/ five of which occur in French and English, and one (the interdental fricative /alpha a/) which occurs only in English. In Experiment 1, an effect of specific linguistic experience was evident for the auditory identification of the non-native interdental stimulus by French-speakers. In Experiment 2, it was shown that the effect of specific language experience extends to the perception of the visible information in speech. These findings are discussed in terms of their implications for our understanding of cross-language processes in speech perception and for our understanding of the development of bimodal speech perception.

Adult↗

PubMed2001

Lesions of the human amygdala impair enhanced perception of emotionally salient events.

Commensurate with the importance of rapidly and efficiently evaluating motivationally significant stimuli, humans are probably endowed with distinct faculties and maintain specialized neural structures to enhance their detection. Here we consider that a critical function of the human amygdala is to enhance the perception of stimuli that have emotional significance. Under conditions of limited attention for normal perceptual awareness-that is, the attentional blink-we show that healthy observers demonstrate robust benefits for the perception of verbal stimuli of aversive content compared with stimuli of neutral content. In contrast, a patient with bilateral amygdala damage has no enhanced perception for such aversive stimulus events. Examination of patients with either left or right amygdala resections shows that the enhanced perception of aversive words depends specifically on the left amygdala. All patients comprehend normally the affective meaning of the stimulus events, despite the lack of evidence for enhanced perceptual encoding of these events in patients with left amygdala lesions. Our results reveal a neural substrate for affective influences on perception, indicating that similar neural mechanisms may underlie the affective modulation of both recollective and perceptual experience.

Adult↗

PubMed1997

Responses of primary visual cortical neurons to binocular disparity without depth perception.

The identification of brain regions that are associated with the conscious perception of visual stimuli is a major goal in neuroscience. Here we present a test of whether the signals on neurons in cortical area V1 correspond directly to our conscious perception of binocular stereoscopic depth. Depth perception requires that image features on one retina are first matched with appropriate features on the other retina. The mechanisms that perform this matching can be examined by using random-dot stereograms, in which the left and right eyes view randomly positioned but binocularly correlated dots. We exploit the fact that anticorrelated random-dot stereograms (in which dots in one eye are matched geometrically to dots of the opposite contrast in the other eye) do not give rise to the perception of depth because the matching process does not find a consistent solution. Anti-correlated random-dot stereograms contain binocular features that could excite neurons that have not solved the correspondence problem. We demonstrate that disparity-selective neurons in V1 signal the disparity of anticorrelated random-dot stereograms, indicating that they do not unambiguously signal stereoscopic depth. Hence single V1 neurons cannot account for the conscious perception of stereopsis, although combining the outputs of many V1 neurons could solve the matching problem. The accompanying paper suggests an additional function for disparity signals from V1: they may be important for the rapid involuntary control of vergence eye movements (eye movements that bring the images on the two foveae into register).

Animals↗

PubMed2003

Environmentally mediated synergy between perception and behaviour in mobile robots.

The notion that behaviour influences perception seems self-evident, but the mechanism of their interaction is not known. Perception and behaviour are usually considered to be separate processes. In this view, perceptual learning constructs compact representations of sensory events, reflecting their statistical properties, independently of behavioural relevance. Behavioural learning, however, forms associations between perception and action, organized by reinforcement, without regard for the construction of perception. It is generally assumed that the interaction between these two processes is internal to the agent, and can be explained solely in terms of the neuronal substrate. Here we show, instead, that perception and behaviour can interact synergistically via the environment. Using simulated and real mobile robots, we demonstrate that perceptual learning directly supports behavioural learning and so promotes a progressive structuring of behaviour. This structuring leads to a systematic bias in input sampling, which directly affects the organization of the perceptual system. This external, environmentally mediated feedback matches the perceptual system to the emerging behavioural structure, so that the behaviour is stabilized.

Adaptation, Physiological↗

PubMed2006

Body mass, weight control behaviours, weight perception and emotional well being in a multiethnic sample of early adolescents.

OBJECTIVE: To investigate weight perception, dieting and emotional well being across the range of body mass index (BMI) in a population-based multiethnic sample of early adolescents. DESIGN: Cross-sectional population-based survey. SUBJECTS: In total, 2789 adolescents 11-14 years of age from three highly deprived regional authorities in East London, in 2001. MEASUREMENTS: Data were collected by student-completed questionnaire on weight perception, dieting history, mental and physical health, health behaviours, social capital and sociodemographic factors. Height and weight were measured by trained researchers. Overweight was defined as BMI > or =85th centile and obesity as BMI > or =98th centile. Underweight was defined as BMI< or =15th centile. RESULTS: In all, 73% were from ethnic groups other than white British. Valid BMI were available for 2522 subjects (90.4%) of whom 14% were obese. Only 20% of overweight boys and 51% of overweight girls assessed their weight accurately. Accuracy of weight perception did not vary between ethnic groups. In all, 42% of girls and 26% of boys reported current dieting to lose weight. Compared with white British teenagers, a history of dieting was more common among Bangladeshi, Indian and mixed ethnicity boys and less likely among Pakistani girls. Self-esteem was not associated with BMI in girls but was significantly lower in obese boys than those of normal weight (P=0.02). Within ethnic subgroups, self-esteem was significantly lower in overweight white British boys (P=0.03) and obese Bangladeshi boys (P=0.01) and Bangladeshi girls (P=0.04), but significantly higher in obese black African girls (P=0.01) than those of normal weight. Obese young people had a higher prevalence of psychological distress (P=0.04), except among Bangladeshi teenagers, where overweight and obese young people had less psychological distress than those of normal weight (P=0.02). Birth outside the UK was associated with reduced risk of obesity in girls (P=0.02) but not with history of dieting, weight perception or psychological factors in either gender. CONCLUSION: High levels of current dieting for weight control and inaccurate perception of body mass are common across all ethnic groups. However, dieting history and the associations of obesity with self-esteem and psychological distress vary between ethnic groups. Interventions to prevent or treat obesity in black or minority ethnicity groups must consider cultural differences in the relationship between body mass, self-esteem and psychological distress.

Adolescent↗

PubMed2001

Relationships among speech perception, production, language, hearing loss, and age in children with impaired hearing.

Eighty-seven primary-school children with impaired hearing were evaluated using speech perception, production, and language measures over a 3-year period. Forty-seven children with a mean unaided pure-tone-average hearing loss of 106 dB HL used a 22-electrode cochlear implant, and 40 with a mean unaided pure-tone-average hearing loss of 78 dB HL were fitted with hearing aids. All children were enrolled in oral/aural habilitation programs, and most attended integrated classes with normally hearing children for part of the time at school. Multiple linear regression was used to describe the relationships among the speech perception, production, and language measures, and the trends over time. Little difference in the level of performance and trends was found for the two groups of children, so the perceptual effect of the implant is equivalent, on average, to an improvement of about 28 dB in hearing thresholds. Scores on the Peabody Picture Vocabulary Test (PPVT) and the Clinical Evaluation of Language Fundamentals showed an upward trend at about 60% of the rate for normally hearing children. Rates of improvement for individual children were not correlated significantly with degree of hearing loss. The children showed a wide scatter about the average speech production score of 40% of words correctly produced in spontaneous conversations, with no significant upward trend with age. Scores on the open-set Consonant-Nucleus-Consonant (CNC) monosyllabic word test and the Bench-Kowal-Bamford (BKB) sentence test were strongly related to language level (as measured by an equivalent age on the PPVT) and speech production scores for both auditory-visual and auditory test conditions. After allowing for differences in language, speech perception scores in the auditory test condition showed a slight downward trend over time, which is consistent with the known biological effects of hearing loss on the auditory periphery and brainstem. Speech perception scores in the auditory condition also decreased significantly by about 5% for every 10 dB of hearing loss in the hearing aid group. The regression analysis model allows separation of the effects of language, speech production, and hearing levels on speech perception scores so that the effects of habilitation and training in these areas can be observed and/or predicted. The model suggests that most of the children in the study will reach a level of over 90% sentence recognition in the auditory-visual condition when their language becomes equivalent to that of a normally hearing 7-year-old, but they will enter secondary school at age 12 with an average language delay of about 4 or 5 years unless they receive concentrated and effective language training.

Age Factors↗

PubMed1983

Perception and production of approximant consonants by normal and articulation-delayed preschool children.

Disagreement exists concerning the relationship between the perception of phonetic contrasts and their production by both normal and articulation-delayed children. The perception of three approximant consonant contrasts (/w/-/r/, /w/-/l/, /r/-/l/) was examined in two groups of 3-year-old children: normal children who did and did not articulate /r/ and /l/ correctly and articulation-delayed children who misarticulated /r/ and /l/. Perception was assessed in a two-choice forced-choice identification task in which the subjects heard a word and pushed a button lighting a picture corresponding to the word. In general, normally developing children were highly accurate in their perception of all three contrasts, but there was more variability in /w/-/l/ perceptual performance among the children who neutralized the /w/-/l/ contrast. Articulation-delayed children displayed a wider range of production patterns and were more variable in their perceptual performance than normally developing children. Results suggest than normally developing children learn to perceive approximant contrasts prior to 3 years of age. However, some but not all articulation-delayed 3-year-old children may still make errors in the perception of approximants.

Articulation Disorders↗