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PubMed2003

Deluding the motor system.

How do we know that our own actions belong to us? How are we able to distinguish self-generated sensory events from those that arise externally? In this paper, I will briefly discuss experiments that were designed to investigate these questions. In particular, I will review psychophysical and neuroimaging studies that have investigated how we recognise the consequences of our own actions, and why patients with delusions of control confuse self-produced and externally produced actions and sensations. Studies investigating the failure of this 'self-monitoring' mechanism in patients with delusions of control will be discussed in the context of the hypothesis that overactivity in the parietal cortex and the cerebellum contribute to the misattribution of an action to an external source.

Awareness↗
PubMed2004

Action, arousal, and subjective time.

Saccadic chronostasis refers to the subjective temporal lengthening of the first visual stimulus perceived after an eye movement. It has been quantified using a duration discrimination task. Most models of human duration discrimination hypothesise an internal clock. These models could explain chronostasis as a transient increase in internal clock speed due to arousal following a saccade, leading to temporal overestimation. Two experiments are described which addressed this hypothesis by parametrically varying the duration of the stimuli that are being judged. Changes in internal clock speed predict chronostasis effects proportional to stimulus duration. No evidence for proportionality was found. Two further experiments assessed the appropriateness of the control conditions employed. Results indicated that the chronostasis effect is constant across a wide range of stimulus durations and does not reflect the pattern of visual stimulation experienced during a saccade, suggesting that arousal is not critical. Instead, alternative processes, such as one affecting the onset of timing (i.e., the time of internal clock switch closure) are implicated. Further research is required to select between these alternatives.

Adult↗
PubMed2006

The effects of eye movements, age, and expertise on inattentional blindness.

Based on various stimuli, the findings for the inattentional blindness paradigm suggest that many observers do not perceive an unexpected object in a dynamic setting. In a first experiment, inattentional blindness was combined with eye tracking data from children. Observers who did not notice the unexpected object in the basketball game test by spent on average as much time (about one second) looking at the unexpected object as those subjects who did perceive it. As such, individual differences that are responsible for the recognition of unexpected objects have to be found as further indicators. In a second experiment, the expert-novice paradigm was used to show that the probability of seeing an unexpected object can be increased with specific previous experience. The results in the same task indicate significant differences between basketball experts and basketball novices. The ages of the subjects in both experiments are discussed in connection with the inattentional blindness paradigm.

Adolescent↗
PubMed2004

An integrated cognitive model of panic disorder: the role of positive and negative cognitions.

One reason for the neglect of the role of positive factors in cognitive-behavioural therapy (CBT) may relate to a failure to develop cognitive models that integrate positive and negative cognitions. Bandura [Psychol. Rev. 84 (1977) 191; Anxiety Res. 1 (1988) 77] proposed that self-efficacy beliefs mediate a range of emotional and behavioural outcomes. However, in panic disorder, cognitively based research to date has largely focused on catastrophic misinterpretation of bodily sensations. Although a number of studies support each of the predictions associated with the account of panic disorder that is based on the role of negative cognitions, a review of the literature indicated that a cognitively based explanation of the disorder may be considerably strengthened by inclusion of positive cognitions that emphasize control or coping. Evidence to support an Integrated Cognitive Model (ICM) of panic disorder was examined and the theoretical implications of this model were discussed in terms of both schema change and compensatory skills accounts of change processes in CBT.

Adaptation, Psychological↗
PubMed2006

Cognitive and perceptual variables in hypochondriasis and health anxiety: a systematic review.

This review examined (a) whether hypochondriacal/health-anxious individuals hold distinct assumptions about health and illness, (b) if triggering these assumptions leads to increased hypochondriacal concerns, and (c) whether these individuals perceive their bodily sensations differently from others (i.e., experience greater somatosensory amplification). There was clear evidence that health anxiety is related dysfunctional health-related beliefs. Few studies have examined how hypochondriacal concerns are triggered, and inconsistent results emerged from those that have. Health anxiety is also associated with self-reported higher levels of somatosensory amplification. However, there was little evidence that individuals high in health anxiety are actually more accurate perceivers of the their own autonomic processes. Although the results generally supported the central tenets of the cognitive-behavioral model of hypochondriasis and health anxiety, further research will be necessary to determine whether these beliefs are specific to hypochondriasis and to identify any cognitive processes that may be unique to hypochondriasis.

Anxiety↗
PubMed2004

Inversion leads to quantitative, not qualitative, changes in face processing.

Humans are remarkably adept at recognizing objects across a wide range of views. A notable exception to this general rule is that turning a face upside down makes it particularly difficult to recognize. This striking effect has prompted speculation that inversion qualitatively changes the way faces are processed. Researchers commonly assume that configural cues strongly influence the recognition of upright, but not inverted, faces. Indeed, the assumption is so well accepted that the inversion effect itself has been taken as a hallmark of qualitative processing differences. Here, we took a novel approach to understand the inversion effect. We used response classification to obtain a direct view of the perceptual strategies underlying face discrimination and to determine whether orientation effects can be explained by differential contributions of nonlinear processes. Inversion significantly impaired performance in our face discrimination task. However, surprisingly, observers utilized similar, local regions of faces for discrimination in both upright and inverted face conditions, and the relative contributions of nonlinear mechanisms to performance were similar across orientations. Our results suggest that upright and inverted face processing differ quantitatively, not qualitatively; information is extracted more efficiently from upright faces, perhaps as a by-product of orientation-dependent expertise.

Adult↗
PubMed2004

Spatial coding of the predicted impact location of a looming object.

Avoiding or intercepting looming objects implies a precise estimate of both time until contact and impact location. In natural situations, extrapolating a movement trajectory relative to some egocentric landmark requires taking into account variations in retinal input associated with moment-to-moment changes in body posture. Here, human observers predicted the impact location on their face of an approaching stimulus mounted on a robotic arm, while we systematically manipulated the relation between eye, head, and trunk orientation. The projected impact point on the observer's face was estimated most accurately when the target originated from a location aligned with both the head and eye axes. Eccentric targets with respect to either axis resulted in a systematic perceptual bias ipsilateral to the trajectory's origin. We conclude that (1) predicting the impact point of a looming target requires combining retinal information with eye position information, (2) that this computation is accomplished accurately for some, but not all, possible combinations of these cues, (3) that the representation of looming trajectories is not formed in a single, canonical reference frame, and (4) that the observed perceptual biases could reflect an automatic adaptation for interceptive/defensive actions within near peripersonal space.

Adult↗
PubMed2004

Orientation-contingent face aftereffects and implications for face-coding mechanisms.

Humans have an impressive ability to discriminate between faces despite their similarity as visual patterns. This expertise relies on configural coding of spatial relations between face features and/or holistic coding of overall facial structure. These expert face-coding mechanisms appear to be engaged most effectively by upright faces, with inverted faces engaging primarily feature-coding mechanisms. We show that opposite figural aftereffects can be induced simultaneously for upright and inverted faces, demonstrating that distinct neural populations code upright and inverted faces. This result also suggests that expert (upright) face-coding mechanisms can be selectively adapted. These aftereffects occur for judgments of face normality and face gender and are robust to changes in face size, ruling out adaptation of low-level, retinotopically organized coding mechanisms. Our results suggest a resolution of a paradox in the face recognition literature. Neuroimaging studies have found surprisingly little orientation selectivity in the fusiform face area (FFA) despite evidence that this region plays a role in expert face coding and that expert face-coding mechanisms are selectively engaged by upright faces. Our results, demonstrating orientation-contingent adaptation of face-coding mechanisms, suggest that the FFA's apparent lack of orientation selectivity may be an artifact of averaging across distinct populations within the FFA that respond to upright and inverted faces.

Adult↗
PubMed2003

Psychological stress and cortisol secretion in anhedonic alcoholic men.

We investigated plasma cortisol in a psychological stress paradigm in seven weaned anhedonic alcoholics in comparison with seven age-matched healthy controls. Alcoholics had significantly higher mean plasma cortisol at baseline and no increase following a psychological stress paradigm. Anhedonic alcoholics judged the experimental situation less agreeable than controls. Anhedonic alcoholics may have blunted cortisol response to psychological stress.

Adult↗
PubMed2004

Temporary DPOAE level shifts, ABR threshold shifts and histopathological damage following below-critical-level noise exposures.

DPOAE temporary level shift (TLS) at 2f(1)-f(2) and f(2)-f(1), ABR temporary threshold shift (TTS), and detailed histopathological findings were compared in three groups of chinchillas that were exposed for 24 h to an octave band of noise (OBN) centered at 4 kHz with a sound pressure level (SPL) of 80, 86 or 92 dB (n=3,4,6). DPOAE levels at 39 frequencies from f(1)=0.3 to 16 kHz (f(2)/f(1)=1.23; L(2) and L(1)=55, 65 and 75 dB, equal and differing by 10 dB) and ABR thresholds at 13 frequencies from 0.5 to 20 kHz were collected pre- and immediately post-exposure. The functional data were converted to pre- minus post-exposure shift and overlaid upon the cytocochleogram of cochlear damage using the frequency-place map for the chinchilla. The magnitude and frequency place of components in the 2f(1)-f(2) TLS patterns were determined and group averages for each OBN SPL and L(1), L(2) combination were calculated. The f(2)-f(1) TLS was also examined in ears with focal lesions equal to or greater than 0.4 mm. The 2f(1)-f(2) TLS (plotted at f(1)) and TTS aligned with the extent and location of damaged supporting cells. The TLS patterns over frequency had two features which were unexpected: (1) a peak at about a half octave above the center of the OBN with a valley just above and below it and (2) a peak (often showing enhancement) at the apical boundary of the supporting-cell damage. The magnitudes of the TLS and TTS generally increased with increasing SPL of the exposure. The peaks of the TLS and TTS, as well as the peaks and valleys of the TLS pattern moved apically as the SPL of the OBN was increased. However, there was little consistency in the pattern relations with differing L(1), L(2) combinations. In addition, neither the 2f(1)-f(2) nor f(2)-f(1) TLS for any L(1), L(2) combination reliably detected focal lesions (100% OHC loss) from 0.4 to 1.2 mm in size. Often, the TLS went in the opposite direction from what would be expected at focal lesions. Recovery from TLS and TTS was also examined in seven animals. Both TLS and TTS recovered partially or completely, the magnitude depending upon exposure SPL.

Animals↗
PubMed2006

Does erythropoietin augment noise induced hearing loss?

Noise-induced hearing loss may result from excessive release of glutamate, nitrogen oxide and reactive oxygen species. The effects of these factors on the inner ear may potentially be prevented or reduced by erythropoietin (EPO), as indicated by previously demonstrated neuro-protective effects of EPO upon damage to the central nervous system and the retina. This paper reports three separate trials, conducted to investigate the hypothesis that noise-induced hearing loss is prevented or reduced by erythropoietin. The trials employed three different modes of drug application, different administration time windows and different rodent species. In trial 1, guinea pigs were exposed to 110dB SPL, 4-20kHz wide band noise (WBN) for 8h. EPO was administered to the round window membrane 24h after noise exposure, either sustained by pump for a week or by single dose middle ear instillation. In trial 2, rats were exposed to 105dB SPL, 4-20kHz WBN for 8h. EPO was administered by single dose middle ear instillation 1 or 14h after noise exposure. In trial 3, rats were exposed to 105dB SPL, 4-20kHz WBN for 8 or 3x8h. EPO was injected intraperitoneally 1h before noise exposure. Oto-acoustic emissions and auditory brainstem responses (at 16kHz) were recorded before and after noise exposure in all trials. The noise exposure induced a hearing loss in all animals. In trial 1, no recovery and no improvement of hearing occurred in any treatment group. In trial 2 and 3, a partial hearing recovery was seen. However, the hearing loss of the EPO treated animals was significantly worse than controls in trial 2. In trial 3, the hearing of the EPO treated animals exposed for 3x8h was significantly worse than controls. Thus, surprisingly, the results from 2 of the 3 present trials indicate that erythropoietin may in fact augment noise-induced hearing loss. This is contradictory to the beneficial effect of EPO reported by the vast majority of studies on stressed neural tissues. EPO administration may alter the blood flow dynamics of the cochlear vascular bed during or after noise exposure, by a potential induction of vasoconstriction. This may be the cause of the surprising findings.

Animals↗
PubMed2006

Factor structure and internal consistency of the Young Schema Questionnaire (Short Form) in Korean and Australian samples.

We investigated cross-cultural differences in the factor structure and psychometric properties of the 75-item Young Schema Questionnaire-Short Form (YSQ-SF). Participants were 833 South Korean and 271 Australian undergraduate students. The South Korean sample was randomly divided into two sub-samples. Sample A was used for Exploratory Factor Analysis (EFA) and sample B was used for Confirmatory Factor Analysis (CFA). EFA for the South Korean sample revealed a 13-factor solution to be the best fit for the data, and CFA on the data from sample B confirmed this result. CFA on the data from the Australian sample also revealed a 13-factor solution. The overall scale of the YSQ-SF demonstrated a high level of internal consistency in the South Korean and Australian groups. Furthermore, adequate internal consistencies for all subscales in the South Korean and Australian samples were demonstrated. In conclusion, the results showed that YSQ-SF with 13 factors has good psychometric properties and reliability for South Korean and Australian University students. Korean samples had significantly higher YSD scores on most of the 13 subscales than the Australian sample. However, limitations of the current study preclude the generalisability of the findings to beyond undergraduate student populations.

Adolescent↗
PubMed2006

The specificity of cognitive vulnerabilities to emotional disorders: anxiety sensitivity, looming vulnerability and explanatory style.

Mood and anxiety disorders share considerable phenomenological and diagnostic overlap. Several models have advanced the understanding of the phenomenological overlap of anxiety and depression; however, identification of disorder-specific etiological mechanisms remains elusive. Recently, research has advanced several cognitive vulnerability-stress models proposing that one's characteristic way of attending to, interpreting, and remembering negative events contributes vulnerability to psychopathology. These cognitive vulnerabilities may elucidate specific etiological mechanisms that distinguish mood and anxiety pathology. The present study examines the specificity of three cognitive vulnerability constructs, the looming cognitive style, anxiety sensitivity, and explanatory style, in the prediction of latent anxiety disorder symptoms and latent depression symptoms. Structural equation modeling analyses indicated that the looming cognitive style demonstrated specificity predicting only anxiety disorder symptoms whereas anxiety sensitivity and a pessimistic explanatory style predicted both anxiety disorder and mood disorder symptoms. Implications for future research are discussed.

Adolescent↗
PubMed2006

Manipulating perceptions of spider characteristics and predicted spider fear: evidence for the cognitive vulnerability model of the etiology of fear.

The present study reports on an attempt to experimentally manipulate perceptions of uncontrollability, unpredictability and dangerousness related to an imaginal encounter with a spider in order to determine whether there is an effect on self-rated predicted spider fear. Experimental manipulations involved differing information in relation to both the spider and the imaginal task. The control, predictability and dangerousness manipulations all had significant main effects on task-related spider fear (TRSF). Measures of the perception of the spiders as uncontrollable, unpredictable and dangerous were also significantly associated with TRSF and accounted for 42% of the variance in predicted fear beyond that accounted for by the experimental manipulations. Results are discussed in terms of their implications for better understanding the etiology and maintenance of fear. The overall findings are consistent with the cognitive vulnerability model, with cognitive perceptions of an object or situation seen as causal determinants of the fear associated with the stimulus.

Adolescent↗
PubMed2005

Stability and discriminative power of the Young Schema-Questionnaire in a Dutch clinical versus non-clinical population.

In this study the temporal stability and general discriminative and classifying ability of the Young Schema-Questionnaire (YSQ) was examined in a clinical and non-clinical sample. To be able to cross-validate on the variables, two parallel subtests, drawn from the YSQ item pool, were utilized. Results suggest adequate rank order stability. However, mean scores tended to drop systematically over time, most likely caused by transient error. Therefore, to assess progress in therapy, the alternate utilization of the parallel parts is advised. Findings from discriminant analysis suggest high sensitivity of the YSQ and its subscales in predicting the presence or absence of psychopathology.

Adolescent↗
PubMed2006

Re-examining sustained attention deficits as vulnerability indicators for schizophrenia: stability in the long term course.

This study examined the longitudinal patterns in the sustained attention deficits detected by the Continuous Performance Test (CPT) and the factors influencing such changes in consecutively admitted schizophrenia patients (n=224) followed up for 4-7 year. Exploratory growth mixture modeling analyses of subjects' CPT performances over successive follow-ups revealed that three major (accounting for 92.8%) plus one minor subgroups could be delineated. Subgrouping was then performed on a subsample of 104 subjects who had at least 3 times of CPT data. Based on subjects' adjusted z score of the test sensitivity index d' derived from comparing with a community sample, patients were divided into three subgroups: no impairment (-1), moderate impairment (-2.5 to -1), and severe impairment (< -2.5). The trajectory taken by individual patient was analyzed according to the initial subgroup status and subsequent changes, controlling for relevant basic and clinical characteristics. Both growth mixture modeling and subgroup status analyses found that around one third of those with severe impairment at baseline showed persistent severe impairment. Those with no impairment were stable and exhibited least tendency for further performance deterioration. Those with moderate impairment tended to fluctuate markedly, mainly towards the better rather than the worse. Previous subgrouping status and concurrent task-taking strategy predicted the performance subgroup status at follow-ups, while clinical symptoms and disease course factors did not. We concluded that there is substantial heterogeneity in schizophrenia patients' long term pattern in sustained attention deficits and those with severe impairment might represent a subgroup with stable vulnerability to schizophrenia.

Adult↗
PubMed2005

Applications of prism adaptation: a tutorial in theory and method.

Data and theory from prism adaptation are reviewed for the purpose of identifying control methods in applications of the procedure. Prism exposure evokes three kinds of adaptive or compensatory processes: postural adjustments (visual capture and muscle potentiation), strategic control (including recalibration of target position), and spatial realignment of various sensory-motor reference frames. Muscle potentiation, recalibration, and realignment can all produce prism exposure aftereffects and can all contribute to adaptive performance during prism exposure. Control over these adaptive responses can be achieved by manipulating the locus of asymmetric exercise during exposure (muscle potentiation), the similarity between exposure and post-exposure tasks (calibration), and the timing of visual feedback availability during exposure (realignment).

Adaptation, Physiological↗