Children's judgments of body size and distortion

Body size estimates of 69 children aged 5–13 years were obtained using a TV video methodology. Tasks included an adjustment procedure where children manipulated the width of their body image on a TV, and a discrete task, where they judged the accuracy of their TV image which was presented as either normal or distorted, that is, too wide or too thin. On the continuous task, judgments were more accurate on ascending trials where children had to increase the width of the image. On the discrete task, a signal detection analysis revealed older children were better in detecting size distortion in their images and that the differences were due to differences in the biological sensory system and not due to a bias to report that they were too fat or too thin. However, there were response bias differences between genders. Females were more likely to report size distortion with increasing age while males were less likely.     

Residual sensory capacities of the deaf: a signal detection analysis of a visual discrimination task.

This experiment compared the visual sensory sensitivity of deaf and hearing subjects in a signal detection paradigm. Subjects (ns = 6) were required to give forced-choice responses to a brightness discrimination task under three stimulus probability conditions (0.25, 0.50, and 0.75). A total of 1,800 trials were given to each subject and utilized to construct isosensitivity functions and d' and Beta, indices for sensory sensitivity and response bias, respectively. The results showed that no enhanced sensory sensitivity is present for these deaf children and questions the classical sensory compensation hypothesis. Furthermore, the deaf subjects responded in a relatively bias-free manner to variations in stimulus probability.     

Pragmatics of measuring recognition memory: applications to dementia and amnesia

This article has two purposes. The first is to describe four theoretical models of yes-no recognition memory and present their associated measures of discrimination and response bias. These models are then applied to a set of data from normal subjects to determine which pairs of discrimination and bias indices show independence between discrimination and bias. The following models demonstrated independence: a two-high-threshold model, a signal detection model with normal distributions using d' and C (rather than beta), and a signal detection model with logistic distributions and a bias measure analogous to C. C is defined as the distance of criterion from the intersection of the two underlying distributions. The second purpose is to use the indices from the acceptable models to characterize recognition memory deficits in dementia and amnesia. Young normal subjects, Alzheimer's disease patients, and parkinsonian dementia patients were tested with picture recognition tasks with repeated study-test trials. Huntington's disease patients, mixed etiology amnesics, and age-matched normals were tested by Butters, Wolfe, Martone, Granholm, and Cermak (1985) using the same paradigm with word stimuli. Demented and amnesic patients produced distinctly different patterns of abnormal memory performance. Both groups of demented patients showed poor discrimination and abnormally liberal response bias for words (Huntington's disease) and pictures (Alzheimer's disease and parkinsonian dementia), whereas the amnesic patients showed the worst discrimination but normal response bias for words. Although both signal detection theory and two-high-threshold discrimination parameters showed identical results, the bias measure from the two-high-threshold model was more sensitive to change than the bias measure (C) from signal detection theory. Three major points are emphasized. First, any index of recognition memory performance assumes an underlying model. Second, even acceptable models can lead to different conclusions about patterns of learning and forgetting. Third, efforts to characterize and ameliorate abnormal memory should address both discrimination and bias deficits.     

Short-term memory for a pure-tone stimulus among mentally retarded and nonretarded persons

Two studies were conducted to determine whether short-term memory performance differences between mentally retarded and nonretarded persons can be attrubuted to the operation of structural features, as contrasted with strategic control processes. The task—discrimination of intensity differences between two pure tones—was selected as one which would minimize specific strategy utilization. In the first experiment normal children, normal adults, and retarded adults were presented with a standard tone and then a comparison tone after an interval of 1, 5 or 10s. Difference limens and constant errors were computed over a substantial number of trials. Measures of intra-individual variability were also obtained. Clear age and IQ-related threshold differences were obtained. Difference thresholds increased over intervals for all groups. However, the critical interaction that would support a theory of differential decay of the memory trace was not obtained. A second experiment, procedurally similar to the first, was conducted using signal detection methodology. The major findings were: (a) groups differed in sensitivity (d′); (b) d′ decreased with increasing separation of standard and comparison tones; (c) d′ increased as the intensity differences between standard and comparison tones increased; and (d) retarded subjects did not alter response bias to changing task requirements Again, however, the interaction of groups and retention interval was not significant. Intelligence and age-related differences in the task occur early in the information processing sequence and appear to be of a perceptual nature.     

Signal-detection analysis of recognition memory of obese subjects

Obese and normal-weight subjects were run on a series of recognition-memory tasks with low and high meaningful CVC trigrams. Subjects received feedback or no feedback regarding the appropriateness of their answers during testing for recognition memory. A signal-detection analysis was used to examine a relatively pure index of memory (d') as compared to response-bias factors [Ln (beta)]. No significant main effect on memory of obese and control subjects was noted although a significant interaction indicated that obese subjects' memory increases over trials in a differential fashion from normal-weight individuals with poorer performance among the obese after 3 trials. Feedback facilitated memory for both groups. Analysis of response criteria [Ln (beta)] showed no significant difference between groups. Highly meaningful trigrams had a significantly lower response criterion than low meaningful trigrams and there was a significant interaction of meaningfulness by trials. An interaction of feedback by meaningfulness was also present. Advantages of using a signal-detection analysis in memory studies comparing obese and normal weight subjects are discussed. Ramifications of the present data for the internality/externality hypothesis of obesity are also discussed.     

Subjective equality and just noticeable differences in body-size judgments by obese persons

Body-size estimates by obese and normal-weight subjects were compared using two different procedures with a TV-video methodology. In the continuous method subjects adjusted an image larger or smaller until they judged a correct TV-image had been achieved. In the second procedure the method of constant stimuli was used wherein values corresponding to the point of subjective equality (PSE) and difference threshold (DL) were determined. No differences between obese and normal-weight subjects were obtained with these procedures. On the continuous task subjects slightly underestimated body size and were more accurate on descending trials where they adjusted the size of the image downwards. With the second procedure, an average PSE of -.62% was obtained, with an average DL = 7.27%. Different PSE values were obtained when subjects were judging whether their image was distorted too wide or too thin. Data from the two procedures are compared and ramifications for the study of body size are discussed.     

Approach bias for food cues in obese individuals

This study aimed to investigate the existence of an approach bias for food cues in obese individuals. A community sample of 56 obese women and 56 normal weight controls completed an approach–avoidance variant of the implicit association task. The obese participants were faster to respond to trials that paired food words with approach words, and trials that paired non-food words with avoid words, than the converse pairings, thus, demonstrating an approach bias for food. This bias was evident for both high caloric and low caloric food words, and was not attributable to a state of deprivation or feelings of hunger. By contrast, the normal weight controls did not show any such bias. The results are consistent with recent neurocognitive perspectives of obesity. At a practical level, approach biases for food may present a potential target for modifying (excessive) food intake.     

Aging and capacity in the same-different judgment

The same-different judgment was used in two experiments to investigate age-group differences in visual processing. Two targets next to fixation were presented; the targets on one-half of the trials were the same, and on the other half of the trials, the targets differed by color, shape, or color and shape (redundant). Response times were lower for redundant trials than for color-only and shape-only trials; this redundancy gain was greater for older observers than for young observers. Capacity measures based on the integrated hazard functions indicated that young adults, but not older adults, experienced a slowing of processing (reduction of capacity) in the redundant condition. These capacity measures may provide a method for interpreting age-group effects in the presence of overall response-time differences.     

Individual differences and weight bias: Do people with an anti-fat bias have a pro-thin bias?

While levels of weight bias vary among individuals, it is not clear why one person possesses stronger anti-fat attitudes than another person. This investigation examined whether individual differences commonly associated with greater anti-fat bias are also associated with a greater preference for thinness among people of varying levels of weight. Young adults (62% women; 84% Caucasian) recruited from psychology classes (N = 308) rated four male and female figures with approximate BMIs of 18.5, 25, 30, and 40, on measures of dislike and personality characteristics and completed measures assessing weight controllability, attitudes toward the obese, and perceptual reliance. Greater negative attitudes, weight controllability beliefs, and perceptual reliance were positively associated with greater dislike and negative personality attributes among obese/severely obese figures, but inversely related among low normal weight figures. Individuals who judge others based on physical features or who view obesity as controllable evidence greater weight bias and a stronger preference for thin body types.     

Enhancement of visual perception under conditions of short-term exposure to sensory isolation: a comparison of procedures for altering vigilance

An experiment was conducted to determine the pre- and posttest performance of subjects on a signal-detection task for the following three experimental conditions: sensory isolation, sensory alertness, and sensory relaxation. All subjects were assessed on 36 pretest and 36 posttest trials. Each block of 36 trials consisted of 12 "strong signals," 12 "weak signals," and 12 "no signals." Exposure durations for each experimental condition lasted for one hour. Analyses showed significant improvements in hits from the pretest trials to the posttest trials on the "strong" and "weak signals" for the sensory isolation condition. Moreover, on the posttest "weak signal" trials, subjects in the sensory isolation condition scored a significantly greater number of hits than did those in the sensory alertness or sensory relaxation conditions. It was concluded that sensory isolation produces perceptual enhancement, as measured by a signal-detection task.     

A computational technique for improving estimates of discriminability and bias across multiple dimensions of choice

Brown and White (2009) proposed measures of discriminability and bias that accommodate additional dimensions of choice—and hence, bias—in conditional discriminations such as matching-to-sample and the yes-no signal detection task. Their proposed measures increase the statistical independence of discriminability and bias estimates, thus improving their accuracy. Because Brown and White’s (2009) equations partition response data more than do standard equations, however, their measures have a slightly lower ceiling. Consequently, measurements can be less accurate when there are few trials and discriminability and bias are extreme. We introduce a computational estimation technique that overcomes this limitation. It estimates Brown and White’s (2009) discriminability and bias measurements from an array of related measures that have a higher ceiling. Simulations show that resulting estimates of discriminability and bias are either comparable to or more accurate than measurements calculated from traditional equations or Brown and White’s (2009) direct measures, even with few trials. A worked example of our technique may be downloaded from brm.psychonomic-journals.org/ content/supplemental.     

Sequential effects in rudimentary auditory and visual tasks

Three experiments examined sequential effects in choice reaction time tasks. On each trial, a right/left positional judgment was made to a either a pure tone or a luminance increment in a visual array of box elements. In the first two experiments, a preparatory signal was presented prior to each imperative signal to indicate the relevant stimulus modality. At a short stimulus onset asynchrony (SOA) between the preparatory and the imperative signal (i.e., 60 msec), subjects were quicker to repeat the same response than to change their response when presented with successive tones, although no such repetition effect occurred on the visual target trials. Subjects were impaired if the stimulus modality changed across successive trials regardless of the modality of the target. At a longer SOA (i.e., 500 msec), these sequential effects were abolished; subjects were assumed to be able to prepare for the relevant modality because of the presentation of the preparatory signal. When the preparatory signals were omitted, in a final experiment, the modality-switching costs were still evident, but now inhibition of return occurred on both the auditory and the visual target trials-subjects were now impaired in responding when the target reappeared at its immediately previous location. It seems, therefore, that the repetition effect and modality-switching effects do dissociate. The data revealed clear differences between orienting attention to a particular spatial locale and focusing attention to a particular sensory modality.     

Signal detection and matching: analyzing choice on concurrent variable-interval schedules.

Pigeons' pecks on a red key and a green key were followed by access to grain according to pairs of concurrent independent variable-interval schedules in a combined signal detection/matching law paradigm. Pecks on the red key were reinforced by the richer variable-interval schedule if a short-duration tone had been presented; pecks on the green key were reinforced by the richer variable-interval schedule if a long-duration tone had been presented. Pecks on the green key given a short-duration tone, or on the red key given a long-duration tone, were reinforced by the leaner variable-interval schedule. The data were analyzed according to both signal detection's and the matching law's separate measures of, first, the discrimination of the choices and, second, the bias to make one response or another. Increasing the difficulty of the tone-duration discrimination decreased both methods' measures of the discrimination of the choices and did not change both methods' measures of the bias to make one response or another. Changing the leaner variable-interval schedule so that it approached the richer variable-interval schedule decreased signal detection's measure of discrimination but left its measure of response bias and the matching law measures unchanged. Data collected only until a subject's first changeover response following presentation of a long or a short tone showed higher values for both methods' measures of discrimination, no change in signal detection's measure of response bias, and lower values for the matching law's measure of response bias. Relationships between the matching law's and signal detection's methods of analyzing choice are discussed. It is concluded that a signal detection analysis is more efficient for examining changes in the difficulty of a discrimination, whereas a matching law analysis is more effective for examining the effects of changes in relative reinforcer frequency.     

Visual temporal integration for threshold,signal detectability,and reaction time measures

A comparison was made of temporal integration for three different response measures in a visual detection task: (1) response frequency, (2) signal detectability as measured for rating ROC curves. (3) simple reaction times (RTs). These measures were obtained on the same trials, to the same stimuli-orange (581 rim) light pulses of 50 min of visual angle fixated foveally and presented to dark-adapted Os in a monocular Maxwellian view. All three response measures showed a period of luminance-duration reciprocity (Bloch’s law), followed by a period of partial integration. The end points of luminance-duration reciprocity (critical duration) and partial integration (utilization time) were shorter for RTs than for the response frequency and signal detectability measures. Neurophysiological.implications of differences in time constants of integration for RT and psychophysical measures are discussed.     

The statistical analysis of concurrent detection ratings

The concurrent detection task is a powerful method for assessing interactions in the processing of two sensory signals. On each trial, a stimulus is presented that is composed of one, both, or neither signal, and the observer makes a detection rating for each stimulus. A classical bivariate signal-detection analysis applies to these data, but is limited by its inability to differentiate certain types of sensory interactions from more cognitive components, and by the lack of an associated testing procedure. The present paper presents an alternative analysis, based on the contingency table of sensory ratings. Six classes of effect can be distinguished and tested: (1) simple response bias, (2) detection of the two signals, (3) interference of each signal on the response to the other signal, (4) sensory and response correlation, (5) bivariate response biases, and (6) higher order association. Complete computational detail is provided.     

On the ability to inhibit simple and choice reaction time responses: a model and a method

This article reports four experiments on the ability to inhibit responses in simple and choice reaction time (RT) tasks. Subjects responding to visually presented letters were occasionally presented with a stop signal (a tone) that told them not to respond on that trial. The major dependent variables were (a) the probability of inhibiting a response when the signal occurred, (b) mean and standard deviation (SD) of RT on no-signal trials, (c) mean RT on trials on which the signal occurred but subjects failed to inhibit, and (d) estimated RT to the stop signal. A model was proposed to estimated RT to the stop signal and to account for the relations among the variables. Its main assumption is that the RT process and the stopping process race, and response inhibition depends on which process finishes first. The model allows us to account for differences in response inhibition between tasks in terms of transformations of stop-signal delay that represent the relative finishing times of the RT process and the stopping process. The transformations specified by the model were successful in group data and in data from individual subjects, regardless of how delays were selected. The experiments also compared different methods of selecting stop-signal delays to equate the probability of inhibition in the two tasks.     

Effects of threat cues on attentional shifting, disengagement and response slowing in anxious individuals

According to cognitive models of anxiety, attentional biases for threat may cause or maintain anxiety states. Previous research using spatial cueing tasks has been interpreted in terms of difficulty in disengaging attention from threat in anxious individuals, as indicated by contrasts of response times (RTs) from threat cue versus neutral cue trials. However, on spatial cueing tasks, differences in RT between threat cue and neutral cue trials may stem from a slowing effect of threat on RT, as well as effects on allocation of visuospatial attention. The present study examined the effects of threat cues on both attentional cueing and response slowing. High and low anxious individuals completed a central cue task, which assessed threat-related response slowing, and a spatial cueing task, which assessed attentional biases for angry, happy and neutral faces. Results indicated that interpretation of the anxiety-related bias for threat depended on whether the effect of response slowing was taken into account. The study illustrates an important problem in using the modified spatial cueing task to assess components of threat-related attentional bias. As this experimental method may reflect both threat-related attentional cueing and response slowing effects, it cannot be assumed to provide pure measures of shift or disengagement components of attention bias.     

Visual field differences for clockwise and counterclockwise mental rotation

Geometric line drawings were presented to normal subjects in the left visual field (LVF) or right visual field (RVF) at various degrees of rotation from a centrally presented vertical standard. The task of the subject was to indicate with a reaction time (RT) response whether the laterally presented stimulus could be rotated into the vertical standard or if it was a rotated mirror image of the standard. In Study 1, an overall right hemisphere superiority was found for RT and accuracy on match trials. Most interestingly, interactions between Visual Field and Rotation Angle for the match accuracy data and between Visual Field and Direction of Rotation (clockwise or counterclockwise) for the match RT slopes were found. These interactions suggested that clockwise rotations were more readily performed in the LVF and counterclockwise rotations in the RVF, consistent with other literature for mental rotation. The purpose of Study 2 was to replicate this finding of visual field differences for rotation direction using a design in which direction and degree of rotation were varied orthogonally. No main effect of Visual Field was found. However, significant interactions between Visual Field and Rotation Angle were found for both RT and accuracy, confirming the presence of visual field differences for rotation direction in a new sample of subjects. These differences were discussed in terms of the possibly greater relevance of medially directed stimuli and a possible hemispheric bias for rotation direction, and in terms of interhemispheric transmission factors.