Signal Detection Procedure Research Articles

Taste thresholds in man are differentially influenced by hydrocortisone and dexamethasone

The present study focused on sensory processing (taste threshold) in healthy young men given different cortisol doses within the normal physiological range. It aimed to differentiate the effects of dexamethasone, a synthetic pure glucocorticoid, compared to hydrocortisone, which has both glucocorticoid and mineralocorticoid properties. In a double-blind, cross-over design, 18 male subjects participated in three sessions. Subjects were pretreated orally with hydrocortisone (50 mg), dexamethasone (2 mg) or placebo. Taste detection was tested by a forced-choice three stimulus drop technique to determine detection acuity and a signal detection procedure to determine the ability to detect differences in NaCl concentration. Cortisol concentrations were determined in blood and saliva. Hydrocortisone and dexamethasone had opposite effects on taste detection acuity. With the highest cortisol levels after intake of hydrocortisone, subjects made more errors is detection trials with respect to stimuli close to the absolute taste detection threshold than after intake of dexamethasone. Detection of differences was impaired by both glucocorticoids. This type of behavioral study in man may help clarify the roles of heterogenous corticosteroid receptor systems within the human brain.

Fine quantization in signal detection and estimation

The performance lost to data quantization in signal detection and estimation procedures is considered. The performance is measured by f-divergences, which are useful indices of discrimination information between statistical hypotheses. Some properties of the f-divergences are briefly discussed, and a general result for the loss in divergence due to uniform data quantization is obtained. Several applications of this result in specific problems of signal detection and estimation being developed, and some numerical results that illustrate the asymptotic behavior of the divergence in these applications are given. The divergence lost to finite nonuniform quantization through the use of a companding model is considered, and the asymptotically optimum nonuniform quantizer within this class is derived. Some interesting problems that remain open are discussed. >

Two-Dimensional Spectral Analysis of Soil Surface Temperature

Soil surface temperature, measured on a 36-by-64 regular grid in a 6-hectare field, is modeled using two-dimensional spectral analysis and a signal-detection procedure. Temperature is found to behave randomly in one direction of the field (width), whereas the distribution in the other direction can be described as a superposition of four cyclic functions. Investigation of the soil temperature’s cyclic behavior revealed that the salt content of the water applied earlier was related spatially to temperature. Different salinities of water had been applied to the field in a cyclic fashion, and co-spectral analysis yielded high correlations at certain frequencies, with higher salinities corresponding to lower temperatures and vice versa.

Orientation discrimination as a function of orientation and spatial frequency.

Orientation discrimination was measured with a yes-no signal detection procedure at two reference orientations, 90° and 45°. For the first of two experiments, the stimuli were disk-shaped gratings, 2.5° in diameter. Their spatial frequencies ranged from 1.8 cpd to 17.6 cpd. For the second experiment, the stimuli were either gratings or bars consisting of the center cycle of the corresponding grating. As expected, the results showed a highly significant reference orientation factor, with smaller just noticeable differences at 90° than at 45° (theoblique effect). However, orientation discrimination was independent of spatial frequency and bar width. Implications of the findings are discussed in relation to a holographic model that relates the oblique effect to meridional differences in the number of orientation-tuned cortical cells.

Alcohol-related ERP changes in cognition

This paper reviews five separate experimental studies concerning the acute or chronic effects of alcohol on late ERP components related to cognitive processes. The studies are evaluated for their adequacy in two arenas: (a) task relevance from a behavioral viewpoint, and (b) their ability to clarify the functional significance of alcohol-related ERP changes. Based upon the general trends of the results reported from the five individual laboratories conducting the investigations, it can be concluded that the P3 component is the most consistently altered of the four late ERP components considered (N1, N2, P2, P3). The finding of a reduced P3 amplitude was more reliable than the finding of increased P3 latency. Alterations in ERP components, when they did occur, occurred under the acute influence of ethanol, as well as in abstinent chronic alcoholics. All of the ERP findings reported were obtained using variations of signal detection procedures. Changes in ERP components did not always parallel performance changes, suggesting that aspects of psychological processes (e.g., attention and stimulus evaluation), presumed to underly ERPs' functional significance, did not directly reflect these processes.

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.

Two-pulse temporal integration functions in the fovea and peripheral retina.

The temporal integration of luminous energy was compared in the fovea and at 7 degrees eccentricity using two-pulse stimuli and two methodologies. The two-pulse stimuli consisted of two 1-msec. light pulses separated by intervals of darkness ranging from 1 to 400 msec.; they were provided by a glow modulator tube transilluminating a 21.8' opal glass target. In Exp. 1 (equal-performance design), integration functions were generated using a forced-choice staircase procedure to estimate threshold luminance. The data for two Os showed that the critical duration (CD), and thus the period of complete integration, was briefer in the fovea than at 7 degrees. Beyond the CD, integration continued to differ for the two retinal locations. In the fovea, two-pulse stimuli beyond CD evidenced partial integration and at the longest stimulus durations no integration or inhibition. In contrast, at 7 degrees stimuli beyond CD appeared to evidence probability summation. In Exp. 2 (equal-energy design), integration functions were generated by measuring the detectability of two-pulse stimuli of different durations but equal in total luminous energy. A signal-detection procedure yielded measures of both response frequency and signal detectability, P(A). The data for two Os showed that for both measures CD was briefer in the fovea than at 7 degrees. Also, in the fovea, long two-pulse stimuli appeared to show no integration or inhibition. Both experiments then showed a foveal-peripheral difference in two-pulse measures of visual temporal integration, with the fovea evidencing less integration. In addition, the forced-choice and signal-detection procedures showed that these loci differences in integration were independent of the Os' response criterion.

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.

Uncertainty tolerance in underwater acoustic signal processing

Because of the difficulties in accurately characterizing the statistical behavior of underwater acoustic channels, tolerance to uncertain statistical modeling is an important property for underwater acoustic signal processing procedures to possess. This paper provides an overview of a number of techniques developed in recent years that can be applied to provide uncertainty tolerance in underwater signal processing applications. In addition to a discussion of general concepts of uncertainty tolerance, specific methods for attaining tolerance to uncertainty in temporal/spatial statistics for procedures such as Wiener and matched filtering, time-delay estimation, sonar system design, and signal prediction are reviewed. Tolerance to uncertainty in amplitude statistics is also a key issue in underwater channels, and techniques for achieving this goal are discussed in the contexts of signal estimation, identification, and detection procedures.

Pain and discomfort thresholds in late pregnancy

Gintzler [6] found an abrupt increase in pain thresholds in rats during the last days of gestation. While some data suggest a similar increase in pain thresholds for pregnant women, Goolkasian and Rimer [7] have found, using signal detection procedures, that women are increasingly likely to report stimuli as painful during the last 2 weeks of pregnancy. The present studies were carried out to assess pain and discomfort thresholds in the last weeks of women's pregnancies. In the first study, daily measures of the pressure-induced pain thresholds of 6 women who had spontaneous, vaginal births increased during the last 16 days of pregnancy and exceeded the 300 mm Hg maximum stimulus pressure for the last 9 days of pregnancy. In the second study, the discomfort thresholds of 6 women were measured each day during the last 11 days of pregnancy before spontaneous vaginal births. The discomfort thresholds of the pregnant women were higher than those of 6 non-pregnant women whose discomfort thresholds were also measured each day. Pregnant women's thresholds increased before the onset of labor, while the discomfort thresholds of the non-pregnant women were unchanged during the course of the study. These results extend Gintzler's findings of reduced sensitivity to pain shortly before parturition.

Effects of electrode location on myoelectric conduction velocity and median frequency estimates.

The effect of surface electrode location on the estimates of the median frequency and conduction velocity of the myoelectric signal was investigated. The locations were identified with respect to the innervation zone and the tendonous portion of the tibialis anterior muscle. Considerable modifications in the median frequency and conduction velocity parameters were noted. The highest values of the median frequency occurred at the region of the innervation zone and tendonous insertion of the muscle, and decreased proportionally with distance from these areas. The rate of change of median frequency was not effected by electrode location. Estimates of conduction velocity were most stable in a region between the distal tendon and the adjacent innervation zone. This region also provided the best linear fit when comparing conduction velocity to median frequency estimates. The implications for signal detection procedures are discussed.

Stimulus discriminability, contingency discriminability, and schedule performance

A detection-theory model to describe the effects of varying stimulus disparity on switching-key concurrent variable-interval schedule performance (Miller, Saunders, & Bourland, 1980) is presented. It describes the available data on stimulus disparity well. Using the additional notion of contingency discriminability, the model is then developed into an account of schedule and stimulus control that is both wider in application and conceptually clearer than the generalized matching law. A basic assumption of the new model is that subjects may not perfectly discriminate that a reinforcer followed a response of one class versus that of another, and this ability is measured as reinforcer-contingency discriminability, dr. This idea is then applied to performance in signal-detection procedures, both with and without error reinforcement, to multiple-schedule performance, and to single-schedule performance. The model fitted the data well, and it thus constitutes a coherent and viable alternative to the generalized matching law in the procedures and conditions in which the latter has been shown to apply.

Two-pulse measures of temporal integration in the fovea and peripheral retina.

The temporal integration of luminous energy was compared in the fovea and at 7 ° eccentricity using a white-appearing stimulus provided by a glow modulator tube transilluminating a 21.8′ opal glass target in a free-viewing situation. In Experiment 1, a three-interval temporal forced-choice adaptive staircase procedure was used to estimate thresholds for brief (3-msec) and long (102-msec) two-pulse stimuli. The data of five observers showed that in the fovea the long stimulus required significantly more luminous energy at threshold than the brief stimulus [t(14) = 5.60, p < .01]; however, at 7°, threshold luminous energy was not significantly different for the brief and long stimulus. Thus, Bloch’s law held in the periphery but not in the fovea, and the critical duration was longer (> 102 msec) in the periphery than in the fovea (< 102 msec). In Experiment 2, the detectability of a brief (3 msec) and a long (102 msec) two-pulse stimulus, both equal in total luminous energy, was compared at the same two retinal locations using a yes-no signal-detection procedure. The data of three observers showed that in the fovea the detectability of the long stimulus was 30% less than that of the brief stimulus, whereas at 7° brief and long stimulus detectability was approximately the same. Thus, both experiments demonstrated a foveal-peripheral difference in two-pulse visual temporal integration, with the fovea evidencing less integration.

Generalised WPD procedure for microprocessor-based signal detection

Generalised WPD procedure for microprocessor-based signal detection

Effects of Intertrial Interval, Orientation, and Adaptation on Orientation Discrimination Measured with a Yes-No Signal Detection Paradigm

Orientation discriminations were measured with a 3.8-cpd sinusoidal grating stimulus and a yes-no signal-detection procedure. Analysis showed that such discriminations are independent of light-adaptation conditions and of intertrial interval over the 2- to 8-sec. range of values explored. However, they are strongly influenced by the orientation where measurements are made (the "oblique effect").

QUANTITATIVE ANALYSIS

Quantitative analysis permits the isolation of invariant relations in the study of behavior. The parameters of these relations can serve as higher-order dependent variables in more extensive analyses. These points are illustrated by reference to quantitative descriptions of performance maintained by concurrent schedules, multiple schedules, and signal-detection procedures. Such quantitative descriptions of empirical data may be derived from mathematical theories, which in turn can lead to novel empirical analyses so long as their terms refer to behavioral and environmental events. Thus, quantitative analysis is an integral aspect of the experimental analysis of behavior.

Stability of neonatal visual behaviors in social interaction

Amphetamine (AMPH) has been prescribed therapeutically for attention-related disorders, weight loss, and to increase attentiveness in the military. It is also widely abused. Signal detection (SD) procedures and analyses have been used extensively with AMPH to assay the potential benefits and risks of the drug. SD procedures, where a participant is tasked with reporting on the presence or absence of unpredictable stimuli for long periods of time, are often used in experiments on sustained attention or vigilance, in both humans and nonhuman animals. In this chapter, we review some of the key elements of signal detection theory and of AMPHs on SD. Our results indicate that AMPHs effects generally follow the Yerkes–Dodson law of arousal. That is, at low doses, AMPH improves SD, but that benefit wanes as dosage increases. At even higher doses, AMPH disrupts SD. These effects appear to cross species distinctions, thereby validating nonhuman animal models in behavioral pharmacology. In addition, there appears to be a tight therapeutically effective dose range, which must be considered in use of AMPH.

A signal detection approach to social perception: identification of negative and positive behaviors by parents of normal and problem children.

The present experiment was designed to investigate differences in the perception of social behavior between parents of normal and problem children and to relate these differences to behavior observed in the home environment. Subjects were brought into the laboratory and asked to identify positive and negative behaviors on a written script portraying family interactions. Correct and incorrect responses were analyzed using signal detection procedures to produce measures of sensitivity and response bias for positive and negative behaviors. These analyses revealed that parents of normal children were better able to discriminate positive behavior than were parents of problem children. Correlations between these responses and data obtained for a subset of the subjects from 1-hour home observations, using a newly developed home observational coding system, revealed a number of relationships between these sets of variables.

Adaptation to air pollution

This study examines human adaptation to air pollution by comparing responses to photochemical smog of long-term residents and recent residents of the Los Angeles air basin. Long-term residents in comparison to recent migrants use a higher response criterion to identify smog in a visual signal detection task. There is no difference in visual sensitivity between the two residential groups in detecting the presence of air pollution in photographic slides. Thus for low levels of visual air pollution, both long-term residents of Los Angeles and new migrants are equally accurate in detecting the presence of smog. Long-term residents, however, are less likely to decide that smog is present in a scene. This response bias is interpreted in terms of adaptation level theory. Characteristics of the response bias differences between the two residential groups are examined in detail using signal detection procedures.

Interferometric refractometer for measuring the relative refractive index of two liquids

An interferometric technique for directly measuring small differences in refractive index between two liquids of similar refractive index is described. The method is based on measuring the phase change on translation normal to the beam propagation in one arm of a Michelson interferometer of a compensating double wedge filled with the two liquids. Details of the sample cell, interferometer construction, signal detection, and experimental procedure are described. Resolution in refractive index difference of 10−6 has been obtained.