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.     

Cue selection in verbal discrimination learning of retarded subjects.

A series of experiments was conducted to examine cue function in trigram verbal discrimination learning by retarded subjects. The issue was to determine the factors that control attention in this type of learning situation. The two variables of chief interest were trigram meaningfulness and reinforcement history. The major general conclusion was that retarded subjects employ complex cue selection strategies in solving a verbal discrimination involving compound verbal stimuli. Major findings were as follows: (a) Retarded subjects exhibit a response bias in favor of words over nonsense trigrams; (b) relatively little active cue selection based on meaningfulness was observed; (c) a compound stimulus discrimination was more difficult to learn than a discrimination involving single verbal stimuli; (d) compound and single stimuli may be processed differently in original discrimination learning; (e) cue position probably controls attention in compound discrimination learning; and (f) a frequency theory of verbal discrimination learning is supported by these data.     

Effects of response disparity on stimulus and reinforcer control in human detection tasks

In two detection experiments, university students reported whether the second of two sequentially presented tones was longer or shorter than the first by responding to stimuli presented on a touch screen. Stimulus disparity and response disparity were manipulated to compare their effects on measures of discrimination and response bias when the reinforcement ratio for correct responses was asymmetric. Choice stimuli consisted of squares filled with different pixel densities. Response disparity was manipulated by varying the difference in density between the two choice stimuli. In both experiments, decreasing stimulus disparity reduced discrimination but had no consistent effect on bias. Decreasing response disparity also reduced discrimination in both experiments, and often reduced estimates of bias. The effects of response disparity on bias were most clear in Experiment 2, in which a greater overall level of response disparity was arranged. The data show that, like corresponding research with pigeons, detection performance of human subjects can be conceptualized as discriminated operants.     

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.     

The effect of context on discrimination and bias in recognition memory for pictures and words

When the context accompanying a to-be-remembered word is changed between study and test, recognition memory is impaired. The deleterious effect of context change on recognition memory can be viewed as support for encoding specificity theory, semantic theory, or the existence of two bases for recognition. A fourth possible interpretation, examined here, is that the effect of context change on recognition memory is due to an accompanying change in response bias, rather than a "true" decrease in sensitivity to old and new items. In two experiments, the effect of context change on discrimination and bias in recognition of simple line drawings and their names was examined. Bias was measured using two measures shown by Snodgrass and Corwin (1988) to be theoretically independent of their associated discrimination measures. Context change produced marked conservatism in response bias in both experiments but demonstrated an effect on discrimination in the second experiment only. The shift from a neutral to a conservative response strategy as a result of context change may also be seen in other experiments, in which the same experimental paradigm was used with a variety of stimulus materials. We suggest that the major effect of context manipulation is to produce a change in bias. A stimulus in a familiar environment appears to be more familiar than a stimulus in a strange environment, regardless of its old/new status. In addition, there appears to be a true decrease in discrimination with context change, but this is more difficult to detect. The finding that pictures, which are less polysemous than words, are as affected by context change as words are supports encoding specificity theory over semantic theory.     

Individual differences in perceptual sensitivity and response bias in anxiety: Evidence from emotional faces

We investigated the perception of emotional stimuli in anxious individuals and non-anxious cohorts. Signal detection theory analysis was applied to the discrimination of emotionally charged faces at several points along a continuum of emotional intensity. This design permitted the derivation of multiple measures of sensitivity and response bias for fearful and for happy faces. Anxious individuals lacked a conservative bias in judging fearful stimuli and a liberal bias in judging positive stimuli compared with non-anxious individuals. In addition, anxious participants had lower perceptual sensitivity (d′) than non-anxious participants for mildly threatening stimuli, as well as a trend towards lower perceptual sensitivity for moderately positive stimuli. These results suggest that the processing of threat information in anxiety is affected by sensitivity and bias differently at different levels of affective intensity.     

Somatosensory processing in the biological relatives of schizophrenia patients: a signal detection analysis of two-point discrimination

This study examined 2-point discrimination performance in 1 st-degree biological relatives (n = 39) of individuals with schizophrenia and normal adult control participants (n = 30) recruited from the community. They completed an objective 2-point discrimination task, adapted for use with a signal detection approach to permit separation of discriminability (i.e., sensitivity, d') from response bias/ criterion (or motivation, lnbeta). Relatives revealed poorer performance on the d' index compared with controls. The 2 groups did not differ on lnbeta, suggesting a genuine difference in sensitivity but not response bias. The sensitivity deficit might reflect decreased spatial acuity and/or impaired intensity cue processing of tactile stimuli. Poor performance on the d' index was most closely associated with 2 schizotypic features, namely "odd beliefs/magical thinking."     

Test of Competing Explanations of the Bizarre Response Bias in Recognition Memory

Recent research has demonstrated that a more liberal response criterion is used when people make judgments about bizarre items than about common items in old-new tests of recognition. The present study was designed to test 2 possible explanations of the bizarre response bias. The bizarre-relations explanation suggests that the bizarre response bias is triggered by the bizarre relations depicted in test items. The target-constituent explanation suggests that the bizarre response bias is the result of a sense of familiarity with constituents of bizarre test items. These explanations were tested by examining the influence of lure manipulations on memory discrimination and response bias for common and bizarre hand-drawn pictures. The results indicated support for the target-constituent explanation by reversing the response bias (obtaining a common response bias) in a recognition test that used common lures containing constituents from bizarre target items and bizarre lures containing constituents from common target items. The results also indicated that increased verbal elaboration enhanced memory discrimination and reduced response bias for both common and bizarre stimuli. The implications of these results are discussed with regard to the false memory controversy.     

Test of competing explanations of the bizarre response bias in recognition memory

Recent research has demonstrated that a more liberal response criterion is used when people make judgments about bizarre items than about common items in old-new tests of recognition. The present study was designed to test 2 possible explanations of the bizarre response bias. The bizarre-relations explanation suggests that the bizarre response bias is triggered by the bizarre relations depicted in test items. The target-constituent explanation suggests that the bizarre response bias is the result of a sense of familiarity with constituents of bizarre test items. These explanations were tested by examining the influence of lure manipulations on memory discrimination and response bias for common and bizarre hand-drawn pictures. The results indicated support for the target-constituent explanation by reversing the response bias (obtaining a common response bias) in a recognition test that used common lures containing constituents from bizarre target items and bizarre lures containing constituents from common target items. The results also indicated that increased verbal elaboration enhanced memory discrimination and reduced response bias for both common and bizarre stimuli. The implications of these results are discussed with regard to the false memory controversy.     

Recognition memory for pictorial stimuli: biasing effects of stimulus emotionality

The possibility that stimulus emotionality might influence recognition bias in a long-term memory task was studied with respect to both the valence and arousal dimensions of emotion. For this purpose, we used 108 International Affective Picture System pictures that were representative of all regions of this two-dimensional space. Signal detection theory analysis was applied using A'and B' D as discrimination and bias measures, respectively. In general, the results showed that greater discrimination was accompanied by a response bias that was more conservative for pleasant and for unarousing pictures than for unpleasant and for arousing ones. These results provide new evidence in connection with the emotion-induced recognition bias in long-term memory performance.     

Measures of sensitivity based on a single hit rate and false alarm rate: the accuracy, precision, and robustness of d', Az, and A'

Signal detection theory offers several indexes of sensitivity (d', Az, and A') that are appropriate for two-choice discrimination when data consist of one hit rate and one false alarm rate per condition. These measures require simplifying assumptions about how target and lure evidence is distributed. We examine three statistical properties of these indexes: accuracy (good agreement between the parameter and the sampling distribution mean), precision (small variance of the sampling distribution), and robustness (small influence of violated assumptions on accuracy). We draw several conclusions from the results. First, a variety of parameters (sample size, degree of discriminability, and magnitude of hits and false alarms) influence statistical bias in these indexes. Comparing conditions that differ in these parameters entails discrepancies that can be reduced by increasing N. Second, unequal variance of the evidence distributions produces significant bias that cannot be reduced by increasing N-a serious drawback to the use of these sensitivity indexes when variance is unknown. Finally, their relative statistical performances suggest that Az is preferable to A'.     

INVOLUNTARY LISTENING AIDS HEARING

Abstract —In two experiments, I simultaneously measured response time, accuracy, and response bias in an auditory intensity discrimination task to look for evidence of stimulus-driven attention orienting in auditory frequency space. The results demonstrated that a cue tone caused an apparently involuntary orienting of attention to the cue's frequency region, allowing faster and more accurate processing of a subsequent target tone when it occurred at the same frequency as the cue than when it occurred at a different frequency. Relationships between response time, accuracy, and bias measures also allowed masking and other effects to be separated from attention-orienting effects in these experiments.     

Dissociating automatic associations: Comparing two implicit measurements of race bias

Weak correspondence across different implicit bias tasks may arise from the contribution of unique forms of automatic and controlled processes to response behavior. Here, we examined the correspondence between estimates of automatic and controlled processing derived from two sequential priming tasks with identical structure and timing designed to separately measure stereotypic (Weapons Identification Task; WIT) and evaluative (Affective Priming Task; APT) associations. Across two studies using predominantly White samples, three consistent patterns emerged in the data: (a) stereotypic bias was stronger for Black targets, whereas evaluative bias was stronger for White targets; (b) overall response accuracy bias correlated modestly across the two tasks; and (c) multinomial processing tree estimates of controlled processing corresponded much more strongly than estimates of automatic processing. These findings support models positing distinct learning and memory systems for different forms of race bias, and suggest that these differing forms contribute to estimates of automatic associations.     

The interaction of stimulus and reinforcer control in complex temporal discrimination.

Six pigeons were trained in a discrete-trials signal-detection procedure to discriminate between a fixed-duration stimulus (5 s or 20 s) and a set of variable durations ranging from 2.5 s to 57.5 s in steps of 5 s. For each fixed-duration stimulus, the ratio of reinforcer frequencies contingent upon reporting the fixed versus the variable stimulus was systematically manipulated. Detection performance was well controlled by both the stimulus value and the reinforcer ratio. Both the discriminability between the fixed duration and the set of variable durations, and the discriminability between the fixed duration and each of the variable durations, were independent of the reinforcer-frequency ratio when discriminability was measured as log d. The sensitivity of response bias to reinforcement-ratio changes was independent of the value of the fixed duration, but was not independent of the discriminability of the variable durations from the fixed durations. Under current models, discriminability measures in complex temporal discrimination may be independent of biasing manipulations, but bias measures are not independent of stimulus values.     

On belief bias in syllogistic reasoning

A multinomial model is used to disentangle the respective contributions of reasoning processes and response bias in conclusion-acceptance data that exhibit belief bias. A model-based meta-analysis of 22 studies reveals that such data are structurally too sparse to allow discrimination of different accounts of belief bias. Four experiments are conducted to obtain richer data, allowing deeper tests through the use of the multinomial model. None of the current accounts of belief bias is consistent with the complex pattern of results. A new theory of belief bias is proposed that assumes that most reasoners construct only one mental model representing the premises as well as the conclusion or, in the case of an unbelievable conclusion, its logical negation. New predictions derived from the theory are confirmed in 4 additional studies.     

Psychophysics of Remembering: The Discrimination Hypothesis

In a psychophysical approach to remembering, the events to be remembered are discriminated from other possibilities at the time of remembering, and not at the time of encoding or learning. The discrimination is specific to the retention interval at which remembering occurs, as shown by experiments demonstrating that discriminability and response bias are delay–specific. This article discusses a discrimination model for remembering that emphasizes the individual's history of learning about reward payoffs in similar experiences in the past. This model predicts the two characteristics of forgetting functions, initial discriminability and rate of forgetting.     

An assessment of response bias for the same-different task: implications for the single-interval task

Two auditory amplitude discrimination experiments were conducted using the same-different experimental design. Observer bias was manipulated, in the first experiment, by varying payoff matrices and, in the second, by varying prior probabilities of signal presentation. Five levels of bias manipulation and four levels of difficulty were employed in each experiment. Each observer received all combinations of bias manipulation and difficulty, but with only one of these combinations within each block of trials. Nine indices of bias were assessed by simultaneously fitting isosensitivity and isobias functions to the data and by fitting isobias functions only. Although none of the indices tested provided an exceptionally good fit to the data, two indices stood out from the rest. These were c*sd and ci, indices with isobias contours similar in shape to those for the c index derived from the yes-no task.     

How to explain receptivity to conjunction-fallacy inhibition training: Evidence from the Iowa Gambling Task

Intuitive predictions and judgments under conditions of uncertainty are often mediated by judgment heuristics that sometimes lead to biases. Using the classical conjunction bias example, the present study examines the relationship between receptivity to metacognitive executive training and emotion-based learning ability indexed by Iowa Gambling Task (IGT) performance. After completing a computerised version of the IGT, participants were trained to avoid conjunction bias on a frequency judgment task derived from the works of Tversky and Kahneman. Pre- and post-test performances were assessed via another probability judgment task. Results clearly showed that participants who produced a biased answer despite the experimental training (individual patterns of the biased → biased type) mainly had less emotion-based learning ability in IGT. Better emotion-based learning ability was observed in participants whose response pattern was biased → logical. These findings argue in favour of the capacity of the human mind/brain to overcome reasoning bias when trained under executive programming conditions and as a function of emotional warning sensitivity.     

The detection model of recognition using know and remember judgments

The signal detection model forknow andremember recognition judgments was tested in two experiments. In Experiment 1, two predictions of the model were tested: (1) that measures of memory sensitivity,A′, are equivalent in value when based on either the recognition (know or remember) criterion or on the remember criterion; and (2) that there is a positive correlation between recognition bias and the proportion of know judgments that are hits, but no correlation between recognition bias and proportion of remember hits (Donaldson, 1996). Both predictions were supported by the data. In Experiment 2, the context of test items was manipulated to make it more or less similar to learning context. The detection model requires that memory sensitivity be the same for both recognition and remember judgments, regardless of test context. Alternatively, if remember judgments reflect only the retrieval of episodic information from memory, the two measures of memory sensitivity should become more disparate in value as learning and test context are made more similar. Memory sensitivity was generally the same in value for recognition and remember criteria but different across context conditions, thus supporting the detection model. The nature of the memory continuum used in detection theory is also discussed.