Detection theory analysis of scaling and discrimination tasks: responses to noxious thermal stimuli

This study's main purpose was to examine the sensitivity estimates obtained from scaling and discrimination approaches for nociception assessment in healthy individuals. This investigation may inform future applications in diagnostic procedures for painful conditions. Models of psychophysical judgment based on those of Durlach and Braida (1969), Laming (1984), and Irwin and Whitehead (1991) were used as the common analytical framework. Noxious thermal contact stimuli were used. The results show that the scaling approach produced lower detection theory sensitivity estimates than did the discrimination approach. The additional judgment variance in scaling tasks could explain this lowered sensitivity. The relative judgmental variance value of 2.18 obtained in this study is lower than variance values found i n previous investigations. This discrepancy i s probably due to the relatively smaller stimulus range employed in this study. The authors propose that the theoretical framework used in this study may be used in future studies to investigate the different dimensions of pain perception.     

Neural computations that underlie decisions about sensory stimuli

Decision-making behavior has been studied extensively, but the neurophysiological mechanisms responsible for this remarkable cognitive ability are just beginning to be understood. Here we propose neural computations that can account for the formation of categorical decisions about sensory stimuli by accumulating information over time into a single quantity: the logarithm of the likelihood ratio favoring one alternative over another. We also review electrophysio-logical studies that have identified brain structures that may be involved in computing this sort of decision variable. The ideas presented constitute a framework for understanding how and where perceptual decisions are formed in the brain.     

Affective ratings of sound stimuli

This article present the Spanish assessments of the 111 sounds included in the International Affective Digitized Sounds (IADS; Bradley &; Lang, 1999b). The sounds were evaluated by 159 participants in the dimensions of valence, arousal, and dominance, using a computer version of the Self-Assessment Manikin (Bradley &; Lang, 1994). Results are compared with those obtained in the American version of the IADS, as well as in the Spanish adaptations of the International Affective Picture System (P. J. Lang, Bradley, &; Cuthbert, 1999; Moltó et al., 1999) and the Affective Norms for English Words (Bradley &; Lang, 1999a; Redondo, Fraga, Padrón, &; Comesaña, 2007).     

Schedules using noxious stimuli. II: low intensity electric shock as a discriminative stimulus

The presence or absence of pulses of low intensity electric shock was used as a discriminative stimulus to control responding under fixed ratio reinforcement in the squirrel monkey. Initially brief periods of nonreinforcement were lengthened only when discriminative control was evident. Discriminative control was studied by (1) varying the duration of nonreinforcement periods; (2) reversing the stimulus conditions correlated with reinforcement and nonreinforcement periods; and (3) determining the minimum shock intensity necessary to maintain discriminative control. Stimulus control was not reliably affected by d-amphetamine, chlorpromazine, or morphine. The discriminative control by pulses of low intensity electric shock was similar to that by other discriminative stimuli, except that the control developed slowly and was better when the pulsing shock was correlated with reinforcement than when correlated with nonreinforcement.     

Culture and sensory response to visual stimuli

This study investigated the influence of culture on people's sensory responses, such as smell, taste, sound and touch to visual stimuli. The sensory feelings of university students from four countries (Japan, South Korea, Britain and France) to six images were evaluated. The images combined real and abstract objects and were presented on a notebook computer. Overall, 280 participants (144 men and 136 women; n = 70/country) were included in the statistical analysis. The chi‐square independence analysis showed differences and similarities in the sensory responses across countries. Most differences were detected in smell and taste, whereas few variations were observed for sound responses. Large variations in the response were observed for the abstract coral and butterfly images, but few differences were detected in response to the real leaf image. These variations in response were mostly found in the British and Japanese participants.     

Effects of rank ordering stimuli on magnitude ratings of these and other stimuli

Five experiments investigated the effects of rank ordering stimuli on subsequent magnitude ratings of these and other stimuli. In Experiments 1 and 2, subjects first rank ordered environmental issues in terms of their importance. Ranking stimuli from “most” to “least” led to more extreme ratings than ranking them from “least” to “most,” regardless of whether the rating criterion was the same as or diametrically opposite to the ranking criterion. (For example, subjects who had previously ranked them beginning with the most important issue subsequently rated these issues not only as more important, but also as more trivial, than did subjects who had ranked them beginning with the least important.) These effects generalized to stimuli other than those that had previously been ranked, and generalized over stimulus domains. (For example, ratings of environmental issues were also affected by ranking the importance of attributes of a marriage partner.) Other experiments in the series circumscribed the conditions in which these effects occur. Results suggested that rank ordering stimuli leads subjects to adopt comparative standards, the use of which generalizes to subsequent magnitude rating tasks and produces an anchoring bias similar to that identified by A. Tversky and D. Kahneman (1974, Science (Washington, D.C.), 185, 1124–1131). Implications of these results for the cognitive processes that underlie social judgment are discussed.     

Behavior simultaneously maintained by both presentation and termination of noxious stimuli

Lever pressing by two squirrel monkeys was maintained under a 3-minute variable-interval schedule of response-produced electric-shock presentation. At the same time, responding on a second lever was maintained under a 3-minute fixed-interval schedule of termination of the shock-presentation schedule and shock-correlated stimuli. Under the termination schedule, the first response after a 3-minute period produced a 1-minute timeout, during which no events occurred and responding had no scheduled consequence. Relatively high and constant rates of responding were maintained on the lever where responding produced shock. Lower rates and positively accelerated patterns of responding occurred on the lever where responding terminated the shock schedule. Thus, responding was simultaneously maintained by presentation of an event and by termination of a stimulus associated with that event. Rates and patterns of responding on each lever were reversed when the schedules arranged on each lever were reversed on two occasions. When shock intensity was increased from 0 to 10 mA, responding maintained both by presentation of shock and by termination of the shock schedule increased, but responding maintained by shock presentation increased to a greater extent. Positive and negative reinforcement, usually regarded as separate behavioral processes involving different events, can coexist when behavior is controlled by different contingencies involving the same event.     

Similarity ratings and confusability of lipread consonants compared with similarity ratings of auditory and orthographic stimuli.

Similarity ratings of pairs of lipread consonants were obtained using a 5-point scale. Matrices were constructed showing mean similarity ratings and confusions among stimuli. Both the similarity and the confusion data provide normative data useful for researchers in many areas. Lipread data collected here are compared with similarity ratings of orthographically and auditorily presented consonants collected by Manning (1977). These comparisons provide information about how stimulus similarity both within and between presentation formats may affect information processing of the three types of stimuli. These data are of special interest to researchers studying the visual processing of speech and the effect of format of presentation on recall.     

False autonomic feedback: Effects of attention to feedback on ratings of erotic stimuli

This study examines the roles played by sound track type, attention to sound track, and meaning of sound track in mediating the effects of false autonomic feedback on attractiveness ratings of erotic stimuli. Male subjects were instructed either to ignore or to pay attention to a pulsed or continuous sound track that was described either as heart-rate feedback or as a neutral auditory stimulus while slides of nude females were shown. Slides associated with a change in either the pulsed sound track or the continuous-tone sound track (increase slides) were subsequently rated as significantly more attractive than those associated with steady sound (stable slides). This effect was contingent on the meaning given to the auditory stimuli, with subjects in the heart-rate condition showing a stronger tendency to rate increase slides more positively than stable slides, by comparison with subjects in the neutral sounds condition. Within the heart-rate condition, subjects told to pay attention to the feedback showed greater rating differences between these two types of slide than those told to ignore it. This pattern of findings contrasts with those of an earlier experiment (Parkinson & Manstead, 1981), where differential unpleasantness ratings of slides of skin diseases depended on the attention paid to the sound track but not on its meaning. It is concluded that the effects of false autonomic feedback are contingent upon the kind of emotional stimuli that are presented.This article is based on research supported by the Economic and Social Research Council (UK). We gratefully acknowledge the assistance of Andrew Gregory, who was responsible for the computer program used in generating the sound track, and we would like to thank the anonymous reviewers for their comments on a previous version of this paper.     

Difference threshold for intensity of tactile stimuli

The difference threshold (DL) for brief tactile stimuli (taps) and vibrotactile stimuli was determined using a 2IFC procedure. The measurements were made at several intensities both in quiet and in the presence of a background vibration. The results show that in the absence of background vibration the DLs for higher intensity stimuli are similar for both taps and vibration, whereas at lower intensities the DL is larger for taps. In the presence of background vibration the DL for vibratory stimuli is elevated to a much greater extent than it is for tap stimuli. The DL is affected by both the intensity of the signal and the intensity of the background vibration.     

False autonomic feedback: Effects of attention to feedback on ratings of pleasant and unpleasant target stimuli

This study investigates the potential interactions among some of the key variables in Valins's (1966) false autonomic feedback paradigm. Subjects were shown mildly pleasant or mildly unpleasant slides of animals while they either paid attention to or ignored a continuous-tone soundtrack that increased in pitch in conjunction with half of the pictures. This soundtrack was described either as feedback of skin conductance level or as a neutral auditory stimulus. Slides associated with increased pitch were generally rated as more affectively potent (in either the positive or negative direction, depending on their initial affective valence). For pleasant slides, this effect was contingent on attention to the soundtrack, such that subjectsignoring the sounds showed a stronger differential rating effect regardless of the meaning ascribed to the sound. For both pleasant and unpleasant slide conditions, the only subject groups showing significant rating effects were those ignoring neutrally described sound. It is argued that this pattern of results poses severe problems for a conventional attributional analysis of the Valins effect.This article is based on research funded by the Economic and Social Research Council (UK) under its Postdoctoral Research Fellowship Scheme. Its contents are the responsibility of the authors and do not necessarily reflect the views of the Economic and Social Research Council.We are grateful to Andrew Gregory for producing the computer program used in generating the soundtrack, and to Tony Manstead for his useful advice about an earlier version of this article.     

The validity of using prior ratings of perceive exertion to regulate resistance exercise intensity

This investigation examined the validity of using ratings of perceived exertion (RPE) to regulate intensity during resistance exercise. 19 male (M age = 22.2 yr., SD = 2.7) and 19 female (M age = 21.4 yr., SD = 2.3) participants estimated exertion when performing the knee extension at 40% to 90% of one-repetition maximum. One week later, participants were asked to produce weights for the knee extension that elicited the feelings of exertion associated with 9, 13, and 17 on the Borg RPE scale. The weight produced at 9, 13, and 17 during the production session was compared to the weight lifted at each RPE during the estimation session. The effect sizes associated with the differences in weight lifted across sessions at each RPE were generally small in magnitude, especially at the higher intensities (ES = .40, -.09, .15, respectively). The results of this investigation support the use of RPE as a method of prescribing the intensity of resistance exercise.     

Acute cortisol elevations cause heightened arousal ratings of objectively nonarousing stimuli

To test the effects of cortisol on affective experience, the authors orally administered a placebo, 20 mg cortisol, or 40 mg cortisol to 85 men. Participants' affective responses to negative and neutral stimuli were measured. Self-reported affective state was also assessed. Participants in the 40-mg group (showing extreme cortisol elevations within the physiological range) rated neutral stimuli as more highly arousing than did participants in the placebo and 20-mg groups. Furthermore, within the 20-mg group, individuals with higher cortisol elevations made higher arousal ratings of neutral stimuli. However, cortisol was unrelated to self-reported affective state. Thus, findings indicate that acute cortisol elevations cause heightened arousal in response to objectively nonarousing stimuli, in the absence of effects on mood.