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PubMed2004

Signal detection theory applied to three visual search tasks--identification, yes/no detection and localization.

Adding distracters to a display impairs performance on visual tasks (i.e. the set-size effect). While keeping the display characteristics constant, we investigated this effect in three tasks: 2 target identification, yes-no detection with 2 targets, and 8-alternative localization. A Signal Detection Theory (SDT) model, tailored for each task, accounts for the set-size effects observed in identification and localization tasks, and slightly under-predicts the set-size effect in a detection task. Given that sensitivity varies as a function of spatial frequency (SF), we measured performance in each of these three tasks in neutral and peripheral precue conditions for each of six spatial frequencies (0.5-12 cpd). For all spatial frequencies tested, performance on the three tasks decreased as set size increased in the neutral precue condition, and the peripheral precue reduced the effect. Larger set-size effects were observed at low SFs in the identification and localization tasks. This effect can be described using the SDT model, but was not predicted by it. For each of these tasks we also established the extent to which covert attention modulates performance across a range of set sizes. A peripheral precue substantially diminished the set-size effect and improved performance, even at set size 1. These results provide support for distracter exclusion, and suggest that signal enhancement may also be a mechanism by which covert attention can impose its effect.

Attention↗
PubMed2001

A nonlinear regression approach to estimating signal detection models for rating data.

This paper considers a regression approach to estimating signal detection parameters for rating data. The methodology is based on the statistical modeling of ordinal data and requires only standard statistical software such as SAS (SAS/STAT User's Guide, 1999) for computation. The approach is more efficient than the current practice of extracting the parameter estimates with the use of specialized software and analyzing the estimates with the use of a standard statistical package. It greatly facilitates exploration of the effects of covariates on model parameters. The method is illustrated using a published data set from a single factor multiple-alternative perceptual task, and data from a more complex factorial design examining recognition memory rating data.

Humans↗
PubMed2004

A signal-detection analysis of sex differences in the perception of emotional faces.

A signal-detection task was used to assess sex differences in emotional face recognition under conditions of uncertainty. Computer images of Ekman faces showing sad, angry, happy, and fearful emotional states were presented for 50 ms to thirty-six men and thirty-seven women. All participants monitored for presentation of either happy, angry, or sad emotional expressions in three separate blocks. Happy faces were the most easily discriminated. Sad and angry expressions were most often mistaken for each other. Analyses of d' values, hit rates, and reaction times all yielded similar results, with no sex differences for any of the measures.

Adolescent↗
PubMed2002

Intramuscular sensation in conscious human subjects: a qualitative and quantitative study utilizing signal detection theory methodology.

To investigate whether human subjects could consciously perceive different levels of intramuscular sensation, EMG needle electrodes were inserted into the forearm extensor musculature. Qualitative descriptions of the types of sensations evoked at various current intensities were recorded. A series of preliminary experiments was performed in order to determine the optimum waveform, current intensity, duration and separation between adjacent current pairs that could reliably be discriminated by conscious human subjects. The methodology of signal detection theory was utilized to obtain the discrimination measure, d' (d prime). Values of d' were obtained for sequential blocks of trials consisting of randomly delivered blocks of 50 "strong" and 50 "weak" stimuli. The ability to discriminate both noxious and non-noxious stimuli was determined using d'. It was demonstrated that human subjects are able to qualitatively describe non-nociceptive sensations elicited by low levels of intramuscular stimulation. Subjects were able to reliably discriminate pairs of electrical stimuli separated in intensity by 0.4 dB over four sequential blocks of trials on the same day and on different days. This work demonstrates that signal detection theory methods can reliably measure sensory discrimination in skeletal muscle, for both noxious and non-noxious levels of electrical stimulation. A protocol is proposed for appropriate future use of this methodology to investigate alterations in muscle sensation following experimental interventions.

Adult↗
PubMed2004

Gender differences in pain perception: a signal detection theory approach.

BACKGROUND: Overseas studies suggest women report more pain and are more vulnerable to chronic pain conditions compared with men, however, it is unclear whether this difference in pain perception is due to sensory or non-sensory factors such as anxiety. Since gender differences in pain perception may have important implications for pain management, it is crucial that the relationship between pain, gender and anxiety in this culture be clarified. METHODS: The Signal Detection Theory Approach was used to determine gender differences in sensory discrimination [P(A)] and response bias (B). One hundred and twenty six Hong Kong Chinese adults responded to thirty pairs of thermal stimuli (36 degrees C-48 degrees C) and their responses to these stimuli were analyzed by computer software. The adapted Chinese version of the State-Trait Anxiety Inventory (STAI-Y) was used to assess state and trait anxiety of participants. RESULTS: Compared with men, women showed enhanced sensory discriminability (P = 0.004) and were less stoical in their response to pain (P = 0.03). Although there was no significant gender difference in state and trait anxiety, sensory discrimination was positively correlated with state anxiety (r = 0.19) and response bias was negatively correlated with trait anxiety (r = -0.18). The content validity index for the STAI-Y was 0.9 and the co-efficient alpha for reliability for state and trait anxiety was 0.88 and 0.92, respectively. CONCLUSIONS: Enhanced sensory discriminability in women may explain why women report more pain and seek healthcare more frequently compared with men. Men showed more stoical response to pain possibly because of gender-role expectations. The Signal Detection Theory approach was instrumental in assessing the sensory and non-sensory dimensions of pain perception. Awareness of the effects of gender and anxiety in pain perception will enable clinicians to be more efficient pain managers.

Adult↗
PubMed2002

A signal detection theory analysis of the placebo effect.

Some instances of the placebo effect may be understood as a particular type of error made by the patient--a false positive error. False positive errors are common (indeed, frequently encouraged) in medical decision making, both by diagnosticians and by patients, and are the inevitable consequence of concluding that an ambiguous signal (e.g., attenuation of pain, relief of depression) did, or did not, occur. Signal detection theory (SDT) was developed to model errors in the detection of ambiguous signals. The authors use SDT to understand the false positive errors that might be made by patients administered a placebo and termed a placebo effect.

Decision Making↗
PubMed1976

Biological signal detection by the autocorrelogram and a recurrence frequency method.

The signal detection property of the autocorrelation function (ACF) is conventionally derived on the assumption of two conditions that may not be present in biological time sequences: (1) the measured variable is assumed to be the sum of a noise and a signal function; (2) the signal function is assumed to continue throughout the sequence. In neuroelectric sequences of all-or-none responses the first assumption would not be appropriate if most of the elements seen by the recording electrode were accessible to the signal input. The sensitivity of the ACF was investigated in simulated sequences in which the random noise was entirely replaced by a periodic square wave signal function for a small number of repetitions and the results compared with a recurrence frequency function (RFF) developed during this work; under these conditions the ACF proved to be significantly inferior. Sensitivity of the ACF was the same for a pure signal function as for an additive function of signal and noise but sensitivity of the RFF was severely degraded for the latter. A variety of neuroelectric sequences was studied and many were found in which strong rhythmic processes revealed by RFF were not detected by the ACF. It is suggested that both methods be used when the signal function may be present during only a small part of the data-collection period and when it is not known to what degree the measured variable may be the sum of a noise and signal function. When an additive function is known to exist, the ACF will be the method of choice; for pure signal functions REF will be more sensitive.

Animals↗
PubMed2002

Grouping participants for tailored work-site weight loss programs: a signal detection approach.

BACKGROUND: Although work-site obesity prevention programs have been widely promoted, they have a high rate of attrition and participants find it very difficult to maintain the decreased weight. It is necessary to develop effective work-site programs that match the type of intervention to the participants and offer the necessary support. To this end, higher-order interaction of the causal factors of obesity needs to be analyzed. METHODS: The subjects were male, white-collar workers (20-64 years of age), in Osaka, Japan. Since conventional methods, such as regression analysis or analysis of variance, cannot deal with the interaction of many variables, signal detection analysis by Kraemer was used to identify the higher-order interaction of multiple predictors of obesity. RESULTS: Out of 15 independent variables, a higher-order interaction consisting of 8 significant variables was identified. Consequently, the subjects were categorized into nine subgroups. It was revealed that the obesity of two groups of workers, 40 or more years old with a high degree of obesity, had different causes: one was related to working conditions, and one was related to smoking cessation. For the other terminal groups, further factors related to obesity were revealed. CONCLUSION: Although the applicability of the findings is limited, the methodology using signal detection analysis might be applicable to other weight loss programs as a way of facilitating the matching of the type of intervention and the target group.

Adult↗
PubMed1980

Reinforcement for errors in a signal-detection procedure.

Six pigeons were trained on a signal-detection procedure. They were required to peck the left key when a 5-second white light had been presented, and the right key when a 10-second light had been presented. These two correct responses were followed by food reinforcement with a probability of .7. Errors, left responses after the 10-second stimulus or right responses after the 5-second stimulus, were initially followed by a 3-second blackout of the chamber. In nine subsequent experimental conditions, errors were followed by food reinforcement with increasing probability while the probability of reinforcement for correct responses was kept constant. The percentage of correct responses decreased as error reinforcement probability increased. A matching model of detection performance, in which discrimination is a joint function of stimulus discriminability and stimulus-reinforcement association, provided a convincing fit to the data and to two sets of published data. The model also fitted published data on multiple and multiple-concurrent free-operant performance. This description of detection performance in terms of matching offers both accurate prediction of complex behavior and measures of discriminability with wide generality.

Journal Article↗
PubMed2001

The effects of aging on reaction time in a signal detection task.

The effects of aging on response time are examined in 2 simple signal detection tasks with young and older subjects (age 60 years and older). Older subjects were generally slower than young subjects, and standard Brinley plot analyses of response times showed typical results: slopes greater than 1 and (mostly) negative intercepts. R. Ratcliff, D. Spieler, and G. McKoon (2000) showed that the slopes of Brinley plots measure the relative standard deviations of the distributions of response times for older versus young subjects. Applying R. Ratcliff's (1978) diffusion model to fit the response times, their distributions, and response accuracy, it was found that the larger spread in older subjects' response times and their slowness relative to young subjects comes from a 50-ms slowing of the nondecision components of response time and more from conservative settings of response criteria.

Adolescent↗
PubMed2002

On the nature of the decision axis in signal-detection-based models of recognition memory.

Most models of recognition memory involve a signal-detection component in which a criterion is placed along a decision axis. Older models generally assume a familiarity-decision axis, but newer models often assume a likelihood ratio axis instead because it allows for a more natural account of the ubiquitous mirror effect. In 3 experiments reported here, item strength was differentially manipulated to see whether a mirror effect would occur. Within a list, the items from 1 category were strengthened by repetition, but the items from another category were not. On the subsequent recognition test, the hit rate was higher for the strong category, but the false-alarm rates for the weak and strong categories were the same (i.e., no mirror effect was observed). This result suggests that the decision axis represents a familiarity scale and that participants adopt a single decision criterion that they maintain throughout the recognition test.

Adult↗
PubMedDate not supplied

Age and disease severity predict choice of atypical neuroleptic: a signal detection approach to physicians' prescribing decisions.

OBJECTIVE: We used a novel application of a signal detection technique, receiver operator characteristics (ROC), to describe factors entering a physician's decision to switch a patient from a typical high potency neuroleptic to a particular atypical, olanzapine (OLA) or risperidone (RIS). METHODS: ROC analyses were performed on pharmacy records of 476 VA patients who had been treated on a high potency neuroleptic then changed to either OLA or RIS. RESULTS: Overall 68% patients switched to OLA and 32% to RIS. The best predictor of neuroleptic choice was age at switch, with 78% of patients aged less than 55 years receiving OLA and 51% of those aged greater than or equal to 55 years receiving OLA (chi(2)=38.2, P<0.001). Further analysis of the former group indicated that adding the predictor of one or more inpatient days to age increased the likelihood of an OLA switch from 78% to 85% (chi(2)=7.3, P<0.01) while further analysis of the latter group indicated that adding the predictor of less than 10 inpatients days to age decreased the likelihood of an OLA switch from 51% to 45% (chi(2)=7.0, P<0.01). CONCLUSIONS: ROC analyses have the advantage over other analyses, such as regression techniques, insofar as their "cut-points" are readily interpretable, their sequential use forms an intuitive "decision tree" and allows the potential identification of clinically relevant "subgroups". The software used in this analysis is in the public domain (http://mirecc.stanford.edu).

Age Factors↗
PubMed1987

[Attention in hyperkinetic children: a signal detection analysis of the effect of methylphenidate].

The effects of methylphenidate on sustained attention were investigated in a placebo-controlled double-blind trial with 20 hyperactive boys of normal intelligence with minimal brain dysfunction (MBD). Using signal detection theory methylphenidate significantly increased sensitivity (d) and did not change response bias (beta), independent of the dosage (5 to 20 mg/d). Responders and nonresponders to methylphenidate were differentiated by signal detection analysis: responders improved primarily in sensitivity, whereas nonresponders changed response bias. No response difference was found in physiological and biochemical measures (catecholamines), showing a general activation caused by methylphenidate. It is discussed that methylphenidate is improving information processing and arousal modulation in responders and is raising unspecific activation in nonresponders.

Attention↗
PubMed1987

A signal detection procedure eliminates priming biases in dichotic listening.

Dichotic digit names were presented to normal right-handed adults in two experiments, the first of which used a standard free report procedure and the second of which used a signal detection procedure. Prior to each test, a priming bias was generated by having subjects monitor either the left or right ear for 30 selective listening trials. The expected priming effect was found in Experiment 1: ear asymmetry and order of report were altered according to the ear previously monitored. In contrast, no priming effect was observed with the signal detection procedure used in Experiment 2. There was a right-ear advantage in sensitivity irrespective of the ear previously monitored. The findings suggest that priming biases act by altering the order in which multiple stimuli are processed and reported.

Adolescent↗
PubMed2002

Is signal detection theory fundamentally flawed? A response to Balakrishnan (1998a, 1998b, 1999).

For nearly 50 years, signal detection theory (SDT; Green & Swvets, 1966; Macmillan & Creelman, 1991) has been of central importance in the development of psychophysics and other areas of psychology. The theory has recently been challenged by Balakrishnan (1998b), who argues that, within SDT, an alternative index is "better justified" than d' and who claims to show (1998a, 1999) that SDT is fundamentally flawed and should be rejected. His evidence is based on new nonparametric measures that he has introduced and applied to experimental data. He believes his results show that basic assumptions of SDT are not supported-in particular, that payoff and probability manipulations do not affect the position of the decision criterion. In view of the importance of SDT in psychology, these claims deserve careful examination. They are critically reviewed here. It appears that it is Balakrishnans arguments that fail, and not SDT

Data Interpretation, Statistical↗
PubMedDate not supplied

The application of the theory of signal detection to the assessment of speech perception.

Traditional audiological measures of speech recognition ability have failed to correlate well with self-assessments of communication difficulty. In this tutorial, an approach to the evaluation of speech perception is described that uses quantities derived from the theory of signal detection. The basics of the theory are reviewed briefly, and its relevance to communication processes is discussed. The measures of performance accuracy and decision criterion provided by the theory of signal detection offer a way of quantifying the ability of a listener to assess the accuracy of his or her own identifications of spoken messages. It is hoped that these quantities will provide new information about communication processes and help to characterize communication difficulties encountered in everyday life.

Audiometry, Speech↗
PubMed1999

Arginine analogs modify signal detection by neurons in the visual cortex.

Nitric oxide (NO) modulates neurotransmitter release, induction of long-term synaptic potentiation and depression, and activity levels of neurons. However, it is not known whether NO contributes to the ability of the CNS to distinguish sensory signals from background noise and/or extract sensory information with greater reliability. We addressed these questions in the visual cortex, in vivo, using electrophysiological recording and analysis of signal detection from individual neurons. This was combined with microiontophoretic application of arginine analogs that either upregulate or downregulate the brain's endogenous NO-generating pathways or compounds that produce exogenous NO. Protocols that enhance NO levels generally increased the number of action potentials per trial evoked by visual stimuli, improved signal detection, and decreased the coefficient of variation of visually evoked responses, whereas NO-reducing protocols predominantly had complementary effects. Control experiments demonstrate that these effects are likely attributable to the specific ability of these arginine compounds to modify NO levels versus other nonspecific effects. Differential effects between neighboring cells and between single-cell receptive subfields suggest that these actions have a significant direct neural component versus exclusively operating indirectly on neurons through the central vascular actions of NO.

Action Potentials↗