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In 21 restrained and 20 unrestrained eaters body size perception was measured sing the video distortion technique (VDT), the image making procedure (IMP) and the kinesthetic size estimating apparatus (KSEA). Body satisfaction was assessed by questionnaires (Body Shape Questionnaire, Dieting scale of the Eating Attitudes Test). Restrained eaters showed no systematic over- or underestimation of the body size but less perceptual accuracy (in VDT and KSEA). Furthermore, they were clearly more dissatisfied with their bodies than unrestrained eaters. Both findings were unrelated to each other. In both groups depressive mood or thoughts seemed to be associated with body dissatisfaction but not with body size misperception. Objective body measures (body mass index, body fat content) were not related to either body size perception or body satisfaction. The findings suggest that a perceptual uncertainty in regard to body size (either for visual or for somatosensory aspects) has already developed in restrained eaters, which may constitute a predisposition for more overt forms of body size misperception as found in eating disorder patients.

19 patients between 23 and 65 yr. of age whose chronic back pain was caused by lumbosacral disk disease and 19 healthy volunteers matched for age and sex were studied. Pain thresholds under phasic and tonic heat stimulation and thermal thresholds for warmth and cold were measured on the right hand. The patients rated any current back pain on a visual analog scale. There was a signigicant negative correlation between current back pain and the threshold for tonic pain, but there was no correlation between current back pain and experimental tonic pain or temperature sensitivity. Hence, current back pain and experimental tonic pain seem to have an additive effect on pain perception because perceptual qualities are similar. Reduced somatosensory perception of chronic back pain patients could be demonstrated for temperature sensitivity and to a lesser degree for phasic pain, but as a consequence of the 'opposing' effect of current back pain, not for tonic pain perception.

To assess temporal variations in the perception of 'phasic' heat pain stimuli a psychophysical tracking procedure was developed that enables repeated assessment of the pain threshold at short intervals. This 'double-tracking' procedure produces two tracking curves simultaneously, one that approaches the pain threshold gradually from above, the other from below. The threshold for phasic heat pain was measured in 80 tracking trials with stimuli at temperatures near the pain threshold. Concurrently, the threshold for 'tonic' heat pain was determined after every 20 tracking trials with a stimulus adjustment procedure. Eleven healthy subjects (age: 24.4 yr. [+ or -] 6.0) participated in 2 sessions each. Phasic stimulation near the pain threshold did not produce any trends in either of the two threshold measures. Hence there was no long-term adaptation or sensitization. However, there were random variations (random walks) in the tracking curves, which we interpret as resulting from a stochastic relationship between stimulus and sensation. In agreement with other reports, discrimination seemed to be better at painful than at nonpainful temperatures.

In a signal-detection experiment, the effects of repeated pain stimulation and the induction of fear on pain thresholds and SDT parameters were studied. 'Signal' and 'no-signal' were not defined physically, but by means of an independent criterion as the primary sensations 'pain' and 'no-pain.' First, the relationship between sensation levels for 'phasic' (short stimulus, used in the SDT procedure) and 'tonic' (longer stimulus, used in the criterion measurement) heat stimuli was determined in 14 subjects. It was quadratic (polynomial regression) and sufficient to define the distinction between 'signal/pain' and 'no-signal/no-pain.' In the signal-detection experiment, change in the SDT parameters (discrimination ability and response bias) was found. Manipulation of anxiety by instructions caused unsystematic changes in discrimination ability. The procedure employed determines both the absolute strength of pain sensation and the ability to discriminate pain from no pain. These variables proved to be independent.