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At least 235 records · Page 13Linked to original sources
PubMed1989

More on volitional experiences and breaching posthypnotic amnesia.

3 experimental conditions using a mock lie detector were employed to investigate further the type of manipulations that lead posthynotically amnesic Ss to breach their amnesia before the reversibility cue is given. 1 condition told Ss they were telling the truth, another that they were lying, and another only that the physiological apparatus could tell whether they were telling the truth. Ss in the "lie" condition breached more than Ss in the other 2 conditions, which did not differ. Ss who rated their recall as in their control (voluntary) were more likely to report more material after breaching manipulations than Ss who reported their recall as not in their control (involuntary). The results are discussed as they relate to breaching conditions and the voluntary/involuntary dimension.

Adult↗
PubMed2003

The effect of volition on the stability of bimanual coordination.

The authors investigated how the intention to passively perform a behavior and the intention to persist with a behavior impact upon the spatial and temporal properties of bimanual coordination. Participants (N = 30) were asked to perform a bimanual coordination task that demanded the continuous rhythmic extension-flexion of the wrists. The frequency of movement was scaled by an auditory metronome beat from 1.5 Hz, increasing to 3.25 Hz in.25-Hz increments. The task was further defined by the requirement that the movements be performed initially in a prescribed pattern of coordination (in-phase or antiphase) while the participants assumed one of two different intentional states: stay with the prescribed pattern should it become unstable or do not intervene should the pattern begin to change. Transitions away from the initially prescribed pattern were observed only in trials conducted in the antiphase mode of coordination. The time at which the antiphase pattern of coordination became unstable was not found to be influenced by the intentional state. In addition, the do-not-intervene set led to a switch to an in-phase pattern of coordination whereas the stay set led to phase wandering. Those findings are discussed within the framework of a dynamic account of bimanual coordination.

Adult↗
PubMed2001

Loss of volition and pain response during induction of anaesthesia with propofol or sevoflurane.

We compared the time to reach two anaesthetic end-points during induction of anaesthesia with a potent inhalation agent (sevoflurane) and an i.v. agent (propofol). We used a method to ensure steady breathing during inhalation induction, and measured loss of tone in the outstretched arm and loss of response to a painful stimulus. Thirty-eight female patients (age 39 (9) yr, weight 65 (11) kg, and height 165 (8) cm) (mean (SD)) were randomly allocated to receive either propofol or sevoflurane. The predicted induction dose of propofol, estimated from age and weight for each patient, was given at a rate of 1% of the induction dose per second, to a possible maximum of 2.5 times the predicted induction dose. Sevoflurane was given with an inhaled concentration of 8%, which was anticipated to cause loss of arm tone within 90-120 s. After loss of consciousness, we applied a painful electrical stimulus to a finger at 15-s intervals and measured the time to loss of motor response. The median times and interquartile values for loss of arm tone were 105 (88-121) s for sevoflurane and 65 (58-80) s for propofol. This was equivalent to 0.65 of the ED(50) of propofol. The time to loss of response to pain was 226 (169-300) s for sevoflurane. The variances of these three measurements were not significantly different, indicating that these dose-response relationships were similar. In contrast, only 11 of the patients given propofol lost the response to pain after 2.5xED(50) had been given. These results support previous evidence of substantial differences between anaesthetic end-points, and show that this evidence can be obtained using a simple and rapid method.

Adolescent↗
PubMed2003

Self-efficacy in sleep apnea: instrument development and patient perceptions of obstructive sleep apnea risk, treatment benefit, and volition to use continuous positive airway pressure.

STUDY OBJECTIVES: The purpose of this study was to evaluate the Self-Efficacy Measure for Sleep Apnea (SEMSA) designed to assess adherence-related cognitions. DESIGN: Subjects completed the questionnaire prior to the initiation of continuous positive airway pressure (CPAP) treatment. Test-retest reliability of the instrument was evaluated by having a subset of subjects complete the SEMSA a second time at home, 1 week later, returning the questionnaire by mail. PATIENTS: 213 subjects with newly diagnosed obstructive sleep apnea were recruited from the clinic populations of 2 sleep disorders centers. MEASUREMENTS AND RESULTS: Content validity was confirmed by a panel of expert judges. Confirmatory factor analysis validated the 3 a priori sub-scales: risk perception, outcome expectancies, and treatment self-efficacy. The internal consistency of the total instrument was 0.92. Test-retest reliability coefficients (N = 20) were estimated to be 0.68, P = 0.001, for Perceived Risk; 0.77, P more more than 0.0001, for Outcome Expectancies; and 0.71, P = 0.0005, for the Treatment Self-Efficacy subscale. Subject responses indicated that approximately half of the subjects did not perceive problems with concentration, sexual performance, sleepy driving, or an accident as related to sleep apnea. More than 60% of the subjects acknowledged most of the benefits of CPAP presented to them, but only 53% associated CPAP use with enhanced sexual performance. Frequently identified barriers to treatment use were nasal stuffiness, claustrophobia, and disturbing bed partner sleep. CONCLUSION: These findings indicate that the SEMSA has strong psychometric properties and has the potential for identifying patient perceptions that may indicate those most likely to not adhere to treatment.

Adult↗
PubMed1987

Maintenance of constant arm position or force: reflex and volitional components in man.

1. Normal subjects, with closed eyes, attempted to keep constant either the force exerted at the wrist or the position of the wrist against an elastic load. The load was attached to the wrist 275 mm from the axis of rotation of the elbow joint. During recording, the far end of the elastic load was displaced slowly enough that it was not immediately perceived but far enough for perception to occur before its completion. 2. The over-all relation between wrist force and position for the two conditions was approximately linear and could be described in terms of effective stiffness. The effective stiffness for the constant-position task averaged 2.8 N/mm (210 N m/rad), while for the constant-force task the mean effective stiffness was -0.028 N/mm (-2.1 N m/rad), indicative of slight over-compensation. 3. Averaging the performance at the onset of the imposed disturbance indicated that the subjects' behaviour consisted of two parts: an initial, small-range response followed by a second phase over the remainder of the displacement. The transition corresponded to the subjects' threshold for detection of the disturbance. 4. The stiffness measured for the response prior to perception was taken as a measure which included the tonic stretch reflex. The stiffness was altered appropriately for the two tasks, being lower when the subjects tried to maintain the force exerted constant (average 1.1 N/mm, 83 N m/rad) than when they attempted to keep the position constant (average 2.3 N/mm, 170 N m/rad). A small degree of co-contraction occurred but could be dissociated from the stiffness changes. 5. Scaling the results allowed comparison of the initial stiffness with values for the decerebrate cat. When analysed in this way, the values recorded in man during the constant-position task were similar to those reported for short-range stiffness in the decerebrate cat. 6. The thresholds for detection of the disturbance were much lower than those reported for subjects with relaxed muscles. 7. The stretch reflex in man has a direct role in compensating for small disturbances during motor tasks. It may also function to improve detection of applied disturbances by magnifying the corresponding force change. Once the stimulus is perceived and voluntary intervention is possible, a greater contrast is seen between the subjects' performance of the two tasks.

Arm↗
PubMed1988

Abolition of methacholine induced bronchoconstriction by the hyperventilation of exercise or volition.

Total pulmonary resistance was measured from continuous records of flow and oesophageal pressure in five normal subjects on three separate days before and after inhalation of methacholine. The dose of methacholine produced, on average, a fivefold increase in airway resistance. Immediately after methacholine inhalation the subjects underwent a progressive exercise test on a cycle ergometer (day 1) or voluntary hyperventilation (day 2) or remained resting (day 3). On the first day during exercise pulmonary resistance fell rapidly to baseline levels within two to three minutes and remained there for the 10 minute duration of the exercise. On day 2 voluntary reproduction of the same level and pattern of ventilation as during exercise resulted in a similar fall of resistance. On the third day, when the subjects remained at rest, pulmonary resistance remained raised for 10 minutes. It is concluded that the bronchodilator effects of exercise can be explained by the increased ventilation rather than the exercise itself, but with much smaller tidal volumes than have previously been thought necessary to reduce drug induced bronchoconstriction.

Adult↗