Biases in the perceived timing of perisaccadic perceptual and motor events

Subjects typically experience the temporal interval immediately following a saccade as longer than a comparable control interval. One explanation of this effect is that the brain antedates the perceptual onset of a saccade target to around the time of saccade initiation. This could explain the apparent continuity of visual perception across eye movements. This antedating account was tested in three experiments in which subjects made saccades of differing extents and then judged either the duration or the temporal order of key events. Postsaccadic stimuli underwent subjective temporal lengthening and had early perceived onsets. A temporally advanced awareness of saccade completion was also found, independently of antedating effects. These results provide convergent evidence supporting antedating and differentiating it from other temporal biases.     

The control of saccade trajectories: direction of curvature depends on prior knowledge of target location and saccade latency

Recent reports have shown that saccades can deviate either toward or away from distractors. However, the specific conditions responsible for the change in initial saccade direction are not known. One possibility, examined here, is that the direction of curvature (toward or away from distractors) reflects preparatory tuning of the oculomotor system when the location of the target and distractor are known in advance. This was investigated by examining saccade trajectories under predictable and unpredictable target conditions. In Experiment 1, the targets and the distractors appeared unpredictably, whereas in Experiment 2 an arrow cue presented at fixation indicated the location of the forthcoming target prior to stimulus onset. Saccades were made to targets on the horizontal, vertical, and principal oblique axis, and distractors appeared simultaneously at an adjacent location (a separation of +/- 45 degrees of visual angle). On average, saccade trajectories curved toward distractors when target locations were unpredictable and curved away from distractors when target locations were known in advance. There was no overall difference in mean saccade latencies between the two experiments. The magnitude of the distractor modulation of saccade trajectory (either toward or away from) was comparable across the different saccade directions (horizontal, vertical, and oblique). These results are interpreted in terms of the time course of competitive interactions operating in the neural structures involved in the suppression of distractors and the selection of a saccade target. A relatively slow mechanism that inhibits movements to distractors produces curvature away from the distractor. This mechanism has more time to operate when target location is predictable, increasing the likelihood that the saccade trajectory will deviate away from the distractor.     

Determinants of lexical access in speech production: Role of word frequency and age of acquisition

The main determinants of lexical access in speech are considered to be a word's age of acquisition (AoA) and its frequency of occurrence in a speaker's experience. It is unclear whether and how these variables interact, although they are commonly observed to be correlated, for the few studies that address the issue have reported inconsistent findings. An influential view of AoA in lexical processing (Ellis and Lambon Ralph, 2000) predicts stronger frequency effects for items acquired later in life than for those acquired at an early age. Five experiments were designed to investigate the possible interaction of AoA and frequency effects in speech. We found that the interaction between word frequency and AoA was not robust and that, contrary to expectation, the effect of word frequency was greater for words acquired earlier in life than for those acquired later. The implications of our findings are discussed.     

Personality prototypes in eating disorders based on the Big Five model

A three factor model of personality pathology was investigated in a clinical sample of 335 female eating disordered patients. Cluster analysis of the Big Five NEO-FFI scales (Costa & McCrae, 1992) yielded three distinct personality profiles, which were consistent with previous studies: (1) a resilient/high functioning cluster with no clinical elevations on the NEO-FFI scales; (2) an undercontrolled/emotionally dysregulated cluster with elevated scores on the Neuroticism scale and low scores on Conscientiousness and Agreeableness; (3) an overcontrolled/constricted cluster showing high scores on Neuroticism and Conscientiousness and low scores on Openness to Experience. Comparing the three personality prototypes with respect to Axis I and Axis II disorders,resilients reported systematically less clinical and personality problems than both undercontrollers and overcontrollers. Compared to the latter, undercontrollers showed more impulsive personality features and behaviors. Finally, cluster membership was not clearly associated with eating disorder subtypes, suggesting that there is considerable variance in personality features and/or pathology within the various eating disorder categories.     

The timing of brain events: authors' response to Libet's 'reply'

A commentary in response to B. Libet: 'The timing of brain events: Reply to the "Special Section" in this journal of September 2004, edited by Susan Pockett' ().     

Retrieval of names in face and object naming in an interference study

Two experiments using the interference paradigm are reported. In the first experiment, the participants spoke aloud the names of celebrities and the names of objects when presented with pictures while hearing distractors. In the case of proper names, we replicated the data obtained by Izaute and Bonin (2001) using the interference paradigm with a proper name written naming task. In the case of common names, the results replicated those obtained by Shriefers, Meyer, and Levelt (1990). In the second experiment, the participants produced the names of celebrities when presented with their faces while hearing distractors that were either proper names associated with the celebrities (associate condition), that belonged to a different professional category (different condition), or that corresponded to the proper names of the celebrities (identical condition). For negative SOAs, "associate" distractors were found to increase latencies compared to the "different category" condition. The implications of the findings for proper name retrieval are briefly discussed.     

Disgust vulnerability and symptoms of contamination-based OCD: descriptive tests of incremental specificity

The present investigation examines the incremental association between disgust propensity and sensitivity and contamination-based obsessive-compulsive disorder (OCD) symptoms. Structural equation modeling in Study 1 indicated that general disgust was related to contamination fear even when controlling for negative affect in a nonclinical sample. Evidence was also found for a model in which the effect of negative affect on contamination fear is mediated by general disgust. Study 1 also showed that both disgust sensitivity and disgust propensity uniquely predicted contamination fear when controlling for negative affect. Growth curve analyses in Study 2 indicated that higher baseline contamination fear is associated with less reduction in contamination fear over a 6-week period as disgust sensitivity increases even when controlling for negative affect. Lastly, disgust propensity was associated with concurrent levels of excessive washing symptoms among patients with OCD in Study 3 when controlling for depression. Implications of these findings from nonclinical, analogue, and clinical samples for future research on the specificity of disgust-related vulnerabilities in the etiology of contamination concerns in OCD are discussed.     

Attempted suppression of social threat thoughts: Differential effects for social phobia and healthy controls?

Thought suppression research in the area of social phobia provides conflicting evidence regarding whether individuals demonstrate a general deficit or successful suppression. This paper reports the outcome of two studies using an online thought suppression paradigm measuring activation of target thoughts. Study 1 examined the effects of suppressing social threat stimuli with a healthy control group. Surprisingly, the results showed that participants demonstrated non-suppression of this stimuli class. Study 2 compared individuals with social phobia to a control group using the same stimuli as Study 1. Results revealed that following instructions to suppress social threat stimuli, individuals with social phobia demonstrated successful suppression, whilst the control group, as in Study 1, did not. The lack of suppression of social threat information by the control group may reflect functional impression-management of social threat stimuli. Whereas, successful suppression of these stimuli by individuals with social phobia, may contribute to diminished habituation to such information.