Individual Variability in Muller-Lyer Illusion Difference Thresholds: Moderating Influences of Hypnotic Susceptibility in Waking and Hypnosis

1994 ◽  
Vol 13 (4) ◽  
pp. 323-333
Author(s):  
Richard P. Atkinson
Keyword(s):  
Standard Stimulus ◽  
Individual Variability ◽  
Psychophysical Method ◽  
Hypnotic Susceptibility ◽  
Lyer Illusion ◽  
Stimulus Difference ◽  
Difference Thresholds ◽  
Method Of Constant Stimuli

This study investigated the differential influences of hypnotic susceptibility on Muller-Lyer illusion difference thresholds in waking and hypnosis using the psychophysical method of constant stimuli. As assessed by the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A) and the Group Stanford Hypnotic Susceptibility Scale, Form C (GSHSS:C), sixteen high (scores = 9–12) and sixteen low (scores = 0–3) hypnotizables participated. In counterbalanced sessions of waking and hypnosis, each subject was sequentially exposed to 110 computer-generated Muller-Lyer illusion pairs of comparison stimuli and a standard stimulus. Difference thresholds for high and low hypnotizables did not differ significantly in waking, but were significantly lower for high than low hypnotizables in hypnosis. Difference thresholds were also significantly lower for high hypnotizables in hypnosis than in waking. Low hypnotizables performed similarly in waking and hypnosis.

A Response-Time Approach for Estimating Sensitivity to Auditory Tempo Changes

2005 ◽  
Vol 22 (3) ◽  
pp. 389-399 ◽  
Author(s):  
Marc Pouliot ◽  
Simon Grondin
Keyword(s):  
Response Time ◽  
Auditory System ◽  
Relative Sensitivity ◽  
Psychophysical Method ◽  
Dynamic Stimuli ◽  
Tempo Change ◽  
Sensitive Tool ◽  
Acceleration And Deceleration ◽  
Musical Condition ◽  
Method Of Constant Stimuli

One of the features of the auditory system is its ability to efficiently process events that occur in rapid succession. The aim of the present study is to propose a new way of investigating sensitivity to auditory tempo changes. More specifically, it proposes to compare the relative sensitivity (bias) to acceleration and deceleration in both musical and monotonal conditions. Bias was measured with (1) a conventional psychophysical method known as the method of constant stimuli (MCS) and (2) a so-called method of dynamic stimuli (MDS). The latter method consists in responding with a finger press as soon as a near-continual tempo change is detected. With the MCS, there was no preference, as estimated by the point of subjective equality, between acceleration and deceleration in the monotonal condition, but there was a preference in the musical condition that indicated more facility for estimating decelerations than accelerations. The results obtained with the MDS are consistent with the MCS results, given that the response time was faster for decelerations than accelerations in the musical condition but not in the monotonal condition. We conclude that the MDS is a sensitive tool for investigating slight tempo variations.

Visual Gap Perception: Judgment Performance at Different Times and the Evaluation of Psychophysical Methods

1978 ◽  
Vol 22 (1) ◽  
pp. 115-115
Author(s):  
Helmut T. Zwahlen
Keyword(s):  
Test Stimulus ◽  
Classical Method ◽  
Standard Stimulus ◽  
Estimation Procedure ◽  
Psychophysical Method ◽  
Computer Simulation Model ◽  
Step Size ◽  
Starting Point ◽  
Stimulus Distance ◽  
The Right

The first part of this study investigated the visual gap judgment performance of twenty-four subjects (21–37 years old) in the laboratory. A scaled down (1:12) two-dimensional gap display (black on yellow background) representing the front silhouette of a car and a post placed on the right side of the car was viewed by the subjects from a distance of 46 inches (total viewing angle of display 17 degrees). The width of the car represented the standard stimulus and the horizontal adjustable distance between the car and the post (gap) represented the test stimulus. The subjects were required to make a forced choice judgment with respect to whether the test stimulus distance (gap) was larger or smaller than the standard stimulus distance (car width). The subjects were tested twice on the same day, once using the randomized classical psychophysical method and once using the Up and Down Transformed Response (U.D.T.R.) rule. The data from the randomized classical psychophysical method was analyzed using the probit and the Kärber method of analysis. The data from the U.D.T.R. method was analyzed using a modified Wetherill estimation procedure. The second part of this study investigated the visual gap judgment performance and eye scanning behavior of two subjects over two days (seven experiments per day). Horizontal eye movements were recorded with a Biometrics Eye Movement Monitor system. The third part of this study investigated the efficacies of two psychophysical methods: The randomized classical method and the sequential U.D.T.R. rule. The results from part one of this study were used to determine a psychometric perception curve of an “average” human being. A digital computer simulation model was built to represent a human being's gap judgment responses and the experimental gap judgment situation. Each method was simulated for the following parameters: the step size between the stimulus levels, the bias of the starting point, and the selected number of trials in an experiment.

Frequency Judgments of Nonretarded and Retarded Individuals

1977 ◽  
Vol 40 (1) ◽  
pp. 199-206
Author(s):  
Terry M. Libkuman ◽  
Douglas D. Friedrich ◽  
Michael K. Holland ◽  
Fred P. Beno
Keyword(s):  
Word Frequency ◽  
Discrimination Learning ◽  
Normal Individual ◽  
Frequency Theory ◽  
Extended Version ◽  
Theory Analysis ◽  
Frequency Judgments ◽  
Difference Thresholds ◽  
The Difference ◽  
Method Of Constant Stimuli

Two experiments were conducted to test the hypothesis derived from an extended version of frequency theory that: retarded individuals relative to MA-matched normals are not as accurate in their ability to detect differences in frequency. The method of constant stimuli was used to obtain an estimate of the difference thresholds based on normative word frequency in Exp. 1 and experimentally manipulated trigram frequency in Exp. 2. The results from Exp. 1 supported the notion that retarded individuals are not as sensitive to differences in frequency as MA-matched normals. However, in Exp. 2 the differences in performance between the two MA-matched groups disappeared. The results were interpreted as indicating that the retarded individual can use the frequency cue as effectively as the normal individual and that the differences reported in Exp. 1 simply reflected the inadequacy of the Thorndike and Lorge (1944) word frequency norms for normal and retarded children. The results were also discussed within the context of a frequency theory analysis of discrimination learning by the retarded.

Judgments of Relative Distance Based on Separate 2-D TV Views

1967 ◽  
Vol 9 (5) ◽  
pp. 447-453
Author(s):  
Billy M. Crawford ◽  
William N. Kama
Keyword(s):  
Depth Perception ◽  
Closed Circuit ◽  
Relative Distance ◽  
Psychophysical Method ◽  
Relative Depth ◽  
Two Dimensional ◽  
Human Capabilities ◽  
Closed Circuit Television ◽  
Difference Thresholds ◽  
Remote Operations

An experiment was conducted to determine human capabilities for making judgments of relative distance based on cues obtained from two ordinary, two-dimensional, closed-circuit television systems. The two cameras were placed so that their lines-of-sight converged symmetrically upon the mid-point between the two rods of a modified Howard-Dolman depth perception apparatus. Four camera lines-of-sight convergence angles were investigated: 15degree, 30°, 60°, and 90°. Difference thresholds for relative depth perception were determined for 24 subjects by the psychophysical Method of Limits. Thresholds were on the order of 12-13 minutes of arc in terms of the parallactic difference angle for the camera lines-of-sight. The results are related to the design of viewing systems for remote operations.

Comparisons of Two Variants of the Method of Constant Stimuli for Estimating Difference Thresholds

2009 ◽  
Vol 68 (4) ◽  
pp. 189-192 ◽  
Author(s):  
Einat Lapid ◽  
Rolf Ulrich ◽  
Thomas Rammsayer
Keyword(s):  
Visual Information ◽  
Pattern Discrimination ◽  
Duration Discrimination ◽  
Line Length ◽  
Difference Limen ◽  
Discrimination Experiment ◽  
Difference Thresholds ◽  
The Difference ◽  
Random Dot Pattern ◽  
Method Of Constant Stimuli

The two-alternative forced-choice (2AFC) and the reminder tasks are variants of the method of constant stimuli. One or the other task is usually employed for estimating the difference limen (DL) in psychophysical research. Lapid, Ulrich, and Rammsayer (2008) found that the 2AFC task yields larger DLs than the reminder task for duration discrimination judgments. The results of the present paper confirm that this discrepancy also generalizes to discrimination judgments about nontemporal, visual information (Experiment 1: Random dot pattern discrimination; Experiment 2: Line-length discrimination). It is argued that this discrepancy is related to the presentation order of the standard and the comparison stimulus.

Müller-Lyer Illusion and Perception of Numerosity

1994 ◽  
Vol 78 (3) ◽  
pp. 937-938
Author(s):  
Tiziano Agostini ◽  
Riccardo Luccio
Keyword(s):  
Magnitude Estimation ◽  
Estimation Method ◽  
Lyer Illusion ◽  
Linear Extent ◽  
Magnitude Estimation Method ◽  
Method Of Constant Stimuli

Illusion of numerosity can be observed in many of the classical illusions of linear extent by replacing the uninterrupted lines with rows of dots. Using the method of constant stimuli both length and numerosity illusions move in the same direction, whereas using a magnitude-estimation method the two illusions move in opposite directions. Two experiments show that this inversion occurs also in the Müller-Lyer illusion.

Effect of Information Feedback on Temporal Discrimination in Concurrent and Post-Feedback Measures

1979 ◽  
Vol 49 (3) ◽  
pp. 935-939 ◽  
Author(s):  
Deborah A. Allenxy ◽  
Cynthia A. Clark
Keyword(s):  
Temporal Discrimination ◽  
Weber Fraction ◽  
Group Differences ◽  
Information Feedback ◽  
Time Intervals ◽  
Feedback Group ◽  
Difference Thresholds ◽  
Nonparametric Estimates ◽  
Slight Advantage ◽  
Method Of Constant Stimuli

College students estimated time intervals (5, 6, 7, 8, and 9 sec.) where one group ( N = 20) received information feedback in terms of actual interval durations and a second group ( N = 18) received no information. Theshold measures were then taken for all subjects using the method of constant stimuli (comparison stimuli of 5, 6, 7, 8, and 9 sec. and a 7-sec. standard). In addition to increased accuracy and consistency of judgments, the feedback group showed a decreasing Weber fraction during the estimation phase, while the Weber fraction for the no-feedback group increased. The feedback group retained only a slight advantage in subsequent threshold measures; group differences in difference thresholds and derived nonparametric estimates of d' were nonsignificant.

The Effect of Psychophysical Method on the Loudness of Continuous and Interrupted Pure Tones

1979 ◽  
Vol 22 (4) ◽  
pp. 717-730
Author(s):  
Dennis Hampton ◽  
Ira M. Ventry
Keyword(s):  
Psychophysical Method ◽  
Experimental Conditions ◽  
Mean Values ◽  
Tracking Method ◽  
Tracking Tasks ◽  
Loudness Judgment ◽  
Pure Tones ◽  
Comfortable Loudness ◽  
Method Of Adjustment ◽  
Method Of Constant Stimuli

Using the Bekesy tracking method for loudness judgment tasks such as most comfortable loudness (MCL) and recalled loudness (RL) measurements, normal listeners have tracked continuous (C) tones at lesser intensities than interrupted (I) tones. The resulting continuous/interrupted (C/I) separations have ranged up to 22 dB. Explanations of the unexpected C/I separations have not been in agreement. The purpose of this study was to investigate whether psychophysical method has a significant effect on the C/I separation. Subjects were six normal-hearing adults, each of whom participated in three practice and ten test sessions of one hour each. Thirty-six experimental conditions were presented. The test signals were C tones, 200/200 msec I tones and 200/800 msec I tones, all at 1 kHz. The reference intensities were 20, 50 and 80 dB SPL. The four methods were Bekesy tracking method (BTM), method of adjustment (MAdj), method of limits (ML) and method of constant stimuli difference (MCSD). Mean values for Point of Subjective Equality and C/I separation were calculated. C/I separations obtained with the BTM were significantly larger than C/I separations obtained with any other psychophysical method. These results demonstrate that C/I separations obtained during suprathreshold Bekesy tracking tasks by normal hearers are largely caused by the measurement method itself rather than by differences in C and I tone loudness. Time order errors could explain the BTM effect.

Stereoscopic Depth Perception in Simulated Displays: What Helps and What Hurts?

1996 ◽  
Vol 40 (23) ◽  
pp. 1193-1196 ◽  
Author(s):  
John W. Akers ◽  
Elizabeth T. Davis ◽  
Robert A. King
Keyword(s):  
Depth Perception ◽  
Stereoscopic Depth ◽  
Stimulus Orientation ◽  
Psychophysical Method ◽  
Depth Information ◽  
Stereoscopic Display ◽  
Retinal Disparity ◽  
Vertical Disparity ◽  
Stereoscopic Displays ◽  
Method Of Constant Stimuli

We tested the effect of direction of retinal disparity and stimulus orientation on stereoscopic depth perception to answer three questions. First, are some directions of disparity more efficient than others in providing stereoscopic depth information? Second, does the orientation of an object affect perceived stereoscopic depth? Third, are there any interactions between these parameters? Subjects were tested using a psychophysical, method of constant stimuli procedure with a modified Wheatstone stereoscopic display. Disparity threshold measurements show a significant effect of direction of retinal disparity. Contrary to expectations however, no significant effect of orientation was found if vertical retinal disparities were excluded from the analyses. Stereoacuity thresholds were measurable with obliquely-oriented stimuli and vertical disparity, however, suggesting that vertical disparities can provide useful information. The implications of these results for the graphics, calibration, and design of stereoscopic displays (e.g., HMDs) are discussed.

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