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At least 37 records · Page 2Linked to original sources
PubMed1986

Effect of wearing chemical protective clothing in the heat on signal detection over the visual field.

Sensitivity for detecting visual signals distributed at various locations throughout the visual field was studied in 16 male subjects who were all exposed to two degrees of ambient heat (91 degrees F/61% RH; 55 degrees F/35% RH) while wearing the Army chemical protective clothing system; also to 70 degrees F/35% RH while wearing Army battle-dress uniform (fatigues). Response time for signal detection increased systematically and significantly with peripheralization of stimulus locations. It was most impaired in the superior and inferior visual field areas and least affected along the horizontal axis area. The data support previous results obtained using this task. Both the MOPP and the heat + MOPP exposure conditions produced highly significant systematic increases in response time to all signals; the worst performance occurred under the heat + MOPP combination. Implications for visual performance while wearing chemical protective gear are discussed.

Adolescent↗
PubMed2005

Sample size and the detection of correlation--a signal detection account: comment on Kareev (2000) and Juslin and Olsson (2005).

Simulations examined the hypothesis that small samples can provide better grounds for inferring the existence of a population correlation, p, than can large samples. Samples of 5, 7, 10, 15, or 30 data pairs were drawn either from a population with p=0 or from one with p>0. When decision accuracy was assessed independently for each level of the decision criterion, there was a criterion-specific small-sample advantage. For liberal criteria, accuracy was greater for large than for small samples, but for conservative criteria, the opposite result occurred. There was no small-sample advantage when accuracy was measured as the area under a receiver operating characteristic curve or as the posterior probability of a hit. The results show that small-sample advantages can occur, but under limited conditions.

Humans↗
PubMed1978

Application of signal detection theory to error detection in ballistic motor skills.

Signal detection procedures were used to measure subjects' ability to detect errors in performance as they tried to hit a target in a ballistic motor task, since current methods were found to have several important shortcomings. Two tasks were used; one involved moving a slide 24.1 cm in 150 msec (temporal target), and the other involved rolling a ball at a visible target (spatial target). Subjects in both tasks were poor at detecting errors. Variability in the perceptual processes, measured by signal detection proceudres, was found to be about twice as much as that in the motor processes, measured by calculating variable error. This finding was inconsistent with a strictly closed-loop model of motor skills. Signal detection theory was also able to fill a gap in present theories of motor learning by explaining why some of the subjects in this experiment were able to detect errors better in the absence of knowledge of results.

Feedback↗
PubMed1999

Differential signal detection system for improved analysis of overlapping signals in liquid chromatography.

We have developed a differential signal detection system for the analysis of liquid chromatographic signals using two or more detectors and a differential amplifier circuit. The proposed detection system is an improvement on conventional chromatography in which signals are detected by means of a single detector. The differential signal detection system eliminates difficulties of isolating minor components of the signal which are masked by the major component, as well as difficulties of separating two components of the signal having similar retention times.

Chromatography, Liquid↗
PubMed1984

Depression, recognition-memory and hedonic tone a signal detection analysis.

A signal detection analysis was used in a recognition memory task involving material of varying hedonic tone. Major differences were found between the control and depressed states. Although overall recognition rates were the same, pleasant material was recognised less and unpleasant material more easily by depressives. Neutral material was recognised equally well by both groups. In the depressed state, response biases were altered such that unpleasant material was handled in a preferential way to neutral or pleasant material.

Adult↗
PubMed1979

Signal detection analysis of conditioning data.

Signal detection analysis of learning and conditioning data provides for a greater distinction to be made between learning and performance through the use of the two signal detection parameters, d' and B. The use of the two parameters permits alternative interpretation of several types of data sets discussed. This analytic technique may be used with either discrete trial or free-response data. The present article reveiws applications of signal detection parameters in the literature, and provides for their extension to other uses.

Conditioning, Classical↗
PubMed1995

Signal detection in averaged evoked potentials: Monte Carlo comparison of the sensitivity of different methods.

Many clinical and research applications rely on detecting evoked potential (EP) signal or EP differences between conditions. Statistical methods for objective signal detection should be sensitive to the presence of signal, but must provide the user strict control on tolerated false alarm rate. The respective sensitivities of 6 signal detection methods were compared through several Monte Carlo simulations involving 2 autocorrelation structures, 5% and 1% significance levels, 8, 10 or 12 replications per study, and increasing signal to noise ratio. The signal detection methods compared were: (1) the Record Orthogonality Test by Permutations (ROT-p), a variant of the Residual Orthogonality Test (Achim et al., 1988), that provides an unbiased estimate of the energy of the signal present in the averaged data, (2) the Tsum2 permutation test of Karniski et al. (1994), (3) a Principal Component Analysis method (PC1) consisting of a t test on the weights of the first principal component, (4) multiple t tests on amplitudes with empirical adjustment for global false alarm rate, and (5-6) the test of Guthrie and Buchwald (1991) on length of consecutive t tests significant at P < 0.05 or 0.01 per-test. The first 3 methods did not exceed their nominal false alarm rate and clearly outperformed the last 3, with the ROT-p method being significantly more sensitive than all others under almost all conditions.

Electrophysiology↗
PubMed1997

Visual signal detectability with two noise components: anomalous masking effects.

We measured human observers' detectability of aperiodic signals in noise with two components (white and low-pass Gaussian). The white-noise component ensured that the signal detection task was always noise limited rather than contrast limited (i.e., image noise was always much larger than observer internal noise). The low-pass component can be considered to be a statistically defined background. Contrast threshold elevation was not linearly related to the rms background contrast. Our results gave power-law exponents near 0.6, similar to that found for deterministic masking. The Fisher-Hotelling linear discriminant model assessed by Rolland and Barrett [J. Opt. Soc. Am. A 9, 649 (1992)] and the modified nonprewhitening matched filter model suggested by Burgess [J. Opt. Soc. Am. A 11, 1237 (1994)] for describing signal detection in statistically defined backgrounds did not fit our more precise data. We show that it is not possible to find any nonprewhitening model that can fit our data. We investigated modified Fisher-Hotelling models by using spatial-frequency channels, as suggested by Myers and Barrett [J. Opt. Soc. Am. A 4, 2447 (1987)]. Two of these models did give good fits to our data, which suggests that we may be able to do partial prewhitening of image noise.

Contrast Sensitivity↗
PubMed1993

Different ways of modeling spatial-frequency uncertainty in visual signal detection.

Inferior human signal-detection behavior compared with that of ideal observers has been explained by intrinsic uncertainty of the human observer with respect to certain signal parameters. One way to model this uncertainty is to assume that the observer simultaneously monitors multiple channels, corresponding to possible parameters. However, it is also conceivable to assume that an observer, uncertain about which channel to monitor, chooses a suboptimally tuned single filter. Finally, uncertainty may also cause the filter underlying a single channel to broaden. In this paper these different models are investigated with respect to spatial-frequency uncertainty for matched filters detecting Gabor signals. All three mechanisms predict a decrease in detection performance. However, it is shown that the resulting psychometric functions are different. While the slopes increase with uncertainty for the multiple-channel models, they decrease for a randomly chosen single channel. Broadening a single filter leads to parallel psychometric functions.

Humans↗
PubMed2002

Noise and coupling affect signal detection and bursting in a simulated physiological neural network.

Signal detection in the CNS relies on a complex interaction between the numerous synaptic inputs to the detecting cells. Two effects, stochastic resonance (SR) and coherence resonance (CR) have been shown to affect signal detection in arrays of basic neuronal models. Here, an array of simulated hippocampal CA1 neurons was used to test the hypothesis that physiological noise and electrical coupling can interact to modulate signal detection in the CA1 region of the hippocampus. The array was tested using varying levels of coupling and noise with different input signals. Detection of a subthreshold signal in the network improved as the number of detecting cells increased and as coupling was increased as predicted by previous studies in SR; however, the response depended greatly on the noise characteristics present and varied from SR predictions at times. Careful evaluation of noise characteristics may be necessary to form conclusions about the role of SR in complex systems such as physiological neurons. The coupled array fired synchronous, periodic bursts when presented with noise alone. The synchrony of this firing changed as a function of noise and coupling as predicted by CR. The firing was very similar to certain models of epileptiform activity, leading to a discussion of CR as a possible simple model of epilepsy. A single neuron was unable to recruit its neighbors to a periodic signal unless the signal was very close to the synchronous bursting frequency. These findings, when viewed in comparison with physiological parameters in the hippocampus, suggest that both SR and CR can have significant effects on signal processing in vivo.

Algorithms↗
PubMed1983

Hemispheric asymmetries in a signal detection task.

Reaction time and signal detection performance were measured during a 78-min. vigilance task. 12 right-handed male subjects served in two experimental sessions. Subjects focused on a central fixation point and responded to signals presented at unpredictable times in one of three locations: 2.5 degrees to right of central fixation, central, and 2.5 degrees to the left of center. Subjects decided whether to press a response key with either the left or right hand with each presentation. Over-all vigilance performance (signal detections and response time) was similar for left and right visual-field presentations. Evidence from reaction times indicated that responses controlled by the left hemisphere were faster to a verbal stimulus (T) while reactions controlled by the right hemisphere were faster to an apparent non-verbal stimulus, an inverted T.

Adult↗
PubMed2007

Moving beyond pure signal-detection models: comment on Wixted (2007).

The dual-process signal-detection (DPSD) model assumes that recognition memory is based on recollection of qualitative information or on a signal-detection-based familiarity process. The model has proven useful for understanding results from a wide range of memory research, including behavioral, neuropsychological, electrophysiological, and neuroimaging studies. However, a number of concerns have been raised about the model over the years, and it has been suggested that an unequal-variance signal-detection (UVSD) model that incorporates separate recollection and familiarity processes (J. T. Wixted, 2007) may provide an equally good, or even better, account of the data. In this article, the authors show that the results of studies that differentiate these models support the predictions of the DPSD model and indicate that recognition does not reflect the summing of 2 signal-detection processes, as the new UVSD model assumes. In addition, the assumptions of the DPSD model are clarified in order to address some of the common misconceptions about the model. Although important challenges remain, hybrid models such as this provide a more useful framework within which to understand human memory than do pure signal-detection models.

Humans↗
PubMed2005

[Effects of slice thickness and matrix size on MRI for signal detection].

High-resolution MRI with increased matrix size is becoming widely used. When matrix size is increased, the signal-to-noise ratio (SNR) decreases. To compensate for a poor SNR, a thick slice is often used. The purpose of this study was to assess whether slice thickness affects the signal detectability of MR images. Signal detectability was evaluated for various slice thicknesses using a contrast-detail phantom. The results showed that thinning slices led to increased signal detection but to decreased SNR because of higher contrast in the partial volume effect. In addition, increasing matrix size and slice thickness for high-resolution imaging led to a decrease in signal detection. It is necessary to consider voxel form for two-dimensional MR images and to recognize that cuboid voxels lead to increased signal detection.

Image Enhancement↗
PubMed2001

Visual signal detection measured by event-related potentials.

Signal Detection tasks typically involve within-subject signal changes. Such a procedure does not lend itself to event-related potential (ERP) experiments where the need for averaging necessitates the maintenance of consistent stimulus parameters. In the present ERP study we adopt a novel approach to thresholding that allows within-subject signal manipulation. The Signal Detection task required the identification of letter targets, formed from dots, in a random dot field. ERP waveforms were segmented into three windows corresponding to N1, N2, and P300 components. Analysis shows that ERP variations are dependent on both task demands and response characteristics for N1, N2, and P300 components.

Adolescent↗
PubMed1987

Odor detection performance of rats following d-amphetamine treatment: a signal detection analysis.

The effects of d-amphetamine sulfate (0.2, 0.4, 0.8, and 1.6 mg/kg SC) on the odor detection performance of 16 adult male Long Evans rats was assessed using high precision olfactometry and a go/no-go operant signal detection task. The drug or saline was administered every 3rd day in a counterbalanced order, with the injections occurring 5 min before each 260-trial test session. Relative to saline, enhanced detection performance to the target stimulus (ethyl acetate), as measured by a non-parametric signal detection index (SI), was observed following administration of 0.2 mg/kg of the drug, whereas decreased detection performance was observed following administration of 1.6 mg/kg of the drug. Significant increases in the responsivity index (RI) occurred at the higher drug dosages for the lower odorant concentrations. In addition, small but statistically significant increases in the latency to respond in the presence of the odor (i.e., S+ response latency) were present at the higher drug dosages. Overall, these data suggest that (a) odor detection performance is enhanced by low doses of amphetamine, (b) odor detection performance is depressed by moderate doses of amphetamine, and (c) drug-related alterations in response criteria occur following the administration of moderate doses of amphetamine.

Animals↗
PubMed2002

Signal detection in conditions of everyday life traffic dilemmas.

This paper shows how the paradigm of signal detection could serve as a viable means for the analysis of drivers' choices in conditions of everyday life traffic dilemmas. The participants were 28 drivers, most of them professional, who spend at least 6 h a day on the road. All agreed to have a note-taking silent passenger for the entire journey, every day during a period of 3-4 weeks. All completed the sensation-seeking questionnaire. Their 'to do or not to do' choices in conditions of four (out of a total of six) traffic dilemmas (amber light, distance keeping, stopping in road-crossing and merging in routes) were analyzable in terms of a modification of the paradigm of signal detection. In accord with the basics of the paradigm of signal detection, the rate of success of the drivers to detect signals of danger on the road (perceptual sensitivity) fell into the range of partial uncertainty (more than 50% and not too much above this level)! The choices made by thrill-and-adventure-seeking drivers were more lenient than the choices of the drivers who scored lower on this dimension.

Accidents, Traffic↗