The psychological representation of speech sounds

If one listens to a meaningless syllable that is repeated over and over, he will hear it undergo a variety of changes. These changes are extremely systematic in character and can be described phonetically in terms of reorganizations of the phones constituting the syllable and changes in a restricted set of distinctive features. When a new syllable is presented to a subject after he has listened to a particular syllable that was repeated, he will misreport the new (test) syllable. His misperception of the test syllable is related to the changes occurring in the representation of the original repeated syllable just prior to the presentation of the test syllable.     

Adaptation to visual rearrangement: Role of sensory discordance

The relative contributions of proprioceptive and efferent information in eliciting adaptation to visual rearrangement were studied under two conditions of visual stimulation. Subjects permitted sight of their forearm under normal room illumination showed significant adaptation when the forearm was (a) moved up and down under the action of tonic vibration reflexes, (b) voluntarily moved through the same trajectory at the same pace, (c) viewed while still, and (d) viewed while the margins of the elbow were vibrated. The reflex movement condition elicited significantly greater adaptation than the other conditions. Subjects allowed only sight of a point source of light attached to their hand showed significant adaptation when the forearm was (a) reflexly moved, (b) voluntarily moved through the same trajectory at the same rate, (c) passively moved, (d) still, and (e) vibrated while still. Less adaptation occurred as the amount of proprioceptive information about limb position was decreased. The adaptation elicited by voluntary movements of the forearm and by reflex movements did not differ significantly. It is concluded that corollary-discharge signals may not be crucial in adaptation to visual rearrangement; a more important factor appears to be discordance between proprioceptive and visual information.     

Adaptation to visual and proprioceptive rearrangement: Origin of the differential effectiveness of active and passive movements

In Experiment 1, subjects exposed to a discordance between the visual and ”proprioceptive” locations of external targets were found to exhibit aftereffects when later pointing without sight of their hands at visual targets. Aftereffects occur both when the discordance is introduced in the traditional fashion by displacing the visual locations of targets and when the proprioceptive locations of targets are displaced. These observations indicate that there is nothing unique about the visual rearrangement paradigm—the crucial factor determining whether adaptation will be elicited is the presence of a discordance in the positional information being conveyed over two different sensory modalities. In a second experiment, the effectiveness of active and passive movements in eliciting adaptation was studied using an experimental paradigm in which subjects were exposed to a systematic discordance between the visual and proprioceptive locations of external targets without ever being permitted sight of their hands; a superiority of active movements was observed, just as is usually found in visual rearrangement experiments in which sight of the hand is permitted. Evidence is presented that the failure of passive movements to elicit adaptation is related to a deterioration in accuracy of position sense information during passive limb movement.     

Who's calling the shots? Intentional content and feelings of control

Based on Pacherie’s dynamic theory of intentions, this study investigated how the way an intention is formed and sustained affects action performance and the experience of control during acting. In Experiment 1, task-irrelevant verbal commands were given while participants responded to stimuli in a two-choice reaction time (RT) task. The commands referred to an action goal congruent or incongruent with the actor’s current intention, or ordered the initiation or abortion of the action. In Experiment 2, the same commands were given as participants freely chose between two actions. The distractors affected performance in the reactive task only. In both experiments, feelings of control were based on movement parameters as well as perceived (mis)matches between distractors and intended actions. These findings suggest that the way an intention is implemented affects how well it can be shielded against external perturbations and how much one feels in control.     

Pain catastrophizing mediates the relationship between worry and pain suffering in patients with irritable bowel syndrome

Although separate lines of behaviorally oriented pain research have drawn attention to the importance of pain catastrophizing and trait worry, little is known about how they work together to influence aspects of chronic pain. Integrating pain research with the broader anxiety, cognitive science, and learning literature, we hypothesized that the process (vs. content) of worry influences pain through catastrophizing. One hundred and eighty-six consecutive patients diagnosed (Rome II) with irritable bowel syndrome completed measures of three dimensions of pain (sensory pain, affective pain, long-term suffering), pain intensity, trait anxiety, worry, catastrophizing, and somatization during baseline assessment of an NIH-funded clinical trial of two psychological treatments. Worry was most strongly associated with the emotionally unpleasant aspects of pain, particularly suffering. Multivariate mediational analyses showed that catastrophizing mediated the link between worry and suffering. Worry, catastrophizing and control variables accounted for 46% of the variance in suffering. Chronic pain patients who worry excessively engage in more catastrophic thinking and through this cognitive process experience more intensely the suffering component of pain. Data are consistent with the notion that worry functions as an "experiential avoidance" strategy for aversive features of pain. Findings are discussed with respect to their relevance to behavioral models for understanding and treating anxiety-related chronic pain disorders.     

Spatial orientation in weightless environments.

Illusions of body inversion and of vehicle inversion can be evoked by exposure to weightlessness in the microgravity conditions of orbital and parabolic flight. Such illusions can involve all possible combinations of self-inversion and vehicle inversion. In the absence of any patterns of external stimulation, individuals may lose all sense of body orientation to their surroundings while retaining a sense of their overall body configuration and cognitive awareness of their actual position. Touch and pressure cues provide a perceptual 'down' in the absence of visual input. When vision is allowed, apparent orientation is influenced by a variety of factors including the direction of gaze, the architectural layout of the vehicle, and sight of the body. The relative importance of the various factors affecting orientation changes with repeated exposure. The virtual absence of sensations of falling during exposure to free-fall emphasizes the role of cognitive factors in experienced orientation.