Distortion, Fill and Noise Effects on Pattern Discrimination

1966 ◽  
Vol 8 (2) ◽  
pp. 147-155
Author(s):  
Raymond B. Webster
Keyword(s):  
Intertrial Interval ◽  
Response Times ◽  
Pattern Discrimination ◽  
Stimulus Presentation ◽  
Basic Pattern ◽  
Male And Female ◽  
Noise Effects ◽  
Presentation Time ◽  
Four Levels ◽  
Method Of Constant Stimuli

This study was conducted in order to investigate the effects of distortion, fill and noise effects on pattern discrimination. Patterns were generated from a 10 × 10 matrix on a random basis and were comprised of black filled squares. There were four levels of pattern fill or complexity. Distortion was the random displacement of basic pattern elements while noise was the filling in of additionally selected (on a random basis) pattern elements. One hundred and forty-four male and female undergraduates served as the subjects. Patterns were projected automatically with a stimulus presentation time of 3.0-sec. and a constant intertrial interval of 5.0-sec. The method of constant stimuli was employed. The results indicated that the discrimination of patterns, as generated in this study, were significantly effected by fill, noise, and distortion at the 0.01 level. Interaction effects were significant also at the same level. Response times were also significantly affected as a function of fill and noise.

Preferred Tempo in Performance of Repetitive Movements

1975 ◽  
Vol 40 (2) ◽  
pp. 439-442 ◽  
Author(s):  
Frank L. Smoll
Keyword(s):  
Sex Differences ◽  
Voluntary Movement ◽  
Motor Response ◽  
Response Times ◽  
Male And Female ◽  
Repetitive Movements

Within- and between- S variability in performance of repetitive movements at a self-paced tempo was studied. Male and female Ss ( Ns = 75) performed 36 consecutive arm swings at an individually chosen tempo. Differences between Ss' selected tempos of performance were considerably greater than the amount of variation in Ss' motor response times, indicating that individuals have preferred tempos of voluntary movement which differ from those of other individuals. No sex differences were evidenced in either preferred tempo or consistency of performance.

Object-Selective Cortex Exhibits Performance-Independent Repetition Suppression

2006 ◽  
Vol 95 (2) ◽  
pp. 995-1007 ◽  
Author(s):  
Rory Sayres ◽  
Kalanit Grill-Spector
Keyword(s):  
Response Time ◽  
Response Times ◽  
Recognition Performance ◽  
Region Of Interest ◽  
Stimulus Presentation ◽  
Repetition Suppression ◽  
Fmri Study ◽  
Bold Responses ◽  
Cortical Regions ◽  
Time Required

Object-selective cortical regions exhibit a decreased response when an object stimulus is repeated [repetition suppression (RS)]. RS is often associated with priming: reduced response times and increased accuracy for repeated stimuli. It is unknown whether RS reflects stimulus-specific repetition, the associated changes in response time, or the combination of the two. To address this question, we performed a rapid event-related functional MRI (fMRI) study in which we measured BOLD signal in object-selective cortex, as well as object recognition performance, while we manipulated stimulus repetition. Our design allowed us to examine separately the roles of response time and repetition in explaining RS. We found that repetition played a robust role in explaining RS: repeated trials produced weaker BOLD responses than nonrepeated trials, even when comparing trials with matched response times. In contrast, response time played a weak role in explaining RS when repetition was controlled for: it explained BOLD responses only for one region of interest (ROI) and one experimental condition. Thus repetition suppression seems to be mostly driven by repetition rather than performance changes. We further examined whether RS reflects processes occurring at the same time as recognition or after recognition by manipulating stimulus presentation duration. In one experiment, durations were longer than required for recognition (2 s), whereas in a second experiment, durations were close to the minimum time required for recognition (85–101 ms). We found significant RS for brief presentations (albeit with a reduced magnitude), which again persisted when controlling for performance. This suggests a substantial amount of RS occurs during recognition.

Temporal Oscillations in Human Perception

1993 ◽  
Vol 4 (4) ◽  
pp. 264-270 ◽  
Author(s):  
Stanislas Dehaene
Keyword(s):  
Task Difficulty ◽  
Response Times ◽  
Human Perception ◽  
Stimulus Presentation ◽  
Human Response ◽  
Time Intervals ◽  
Discrete Processing ◽  
Processing Steps ◽  
Continuous Accumulation

The notion that human perceptual decisions are based on discrete processing cycles rather than a continuous accumulation of information was examined experimentally. Significant periodicities were found in human response times (RT) to feature and conjunction discrimination tasks in the visual and auditory modalities. Individual RT histograms were multimodal, with regularly spaced peaks and troughs, indicating that responses were emitted more frequently at regularly recurring time intervals following stimulus presentation. On average, responses were initiated after four to seven discrete processing steps whose “quantum” duration was proportional to task difficulty.

CHICK EMBRYONIC DEVELOPMENT AS INFLUENCED BY IN OVO INJECTED SELENIUM

1978 ◽  
Vol 58 (2) ◽  
pp. 227-232 ◽  
Author(s):  
R. C. FITZSIMMONS ◽  
K. PHALARAKSH
Keyword(s):  
Dry Weight ◽  
Embryo Morphology ◽  
In Ovo ◽  
Female Embryo ◽  
Protein Nitrogen ◽  
Male And Female ◽  
Embryo Mortality ◽  
Significant Depression ◽  
Wet Weight ◽  
Four Levels

Fresh fertile eggs were injected with four levels of selenium (as sodium selenite) into the air cell and examined after various times of incubation. The treatment effects on embryo morphology, stage of embryo mortality and body weight are reported. The correlation between wet weight vs. dry weight and protein nitrogen was 0.99 and 0.94, respectively, for the 2- to 5-day incubation period. The coefficient of correlation for wet weight vs. dry weight from 6 to 18 days of incubation was also very high (r = 0.97). The four selenium (Se) treatment levels (0.15, 0.30, 0.45, and 0.60 ppm of added Se per embryo) resulted in a significant depression of embryo wet weights at 3 and 4 days of incubation but not at 2 days. There was no treatment effect on male and female embryo wet weights from 6 to 18 days of incubation. Furthermore, there was no significant differences between male and female wet weights during this latter period. The embryo mortality resulting from the above Se treatments was 16.2, 15.1, 28.2 and 29.0%, respectively (control mortality was 8.2%), and 99% of these embryos did not develop beyond the 6-day stage. No morphological abnormalities were observed from the Se treatments.

scholarly journals Recognition and discrimination of unfamiliar male and female voices

2017 ◽  
Vol 3 (1) ◽  
pp. 52-60
Author(s):  
Antonio L Manzanero ◽  
Susana Barón
Keyword(s):  
Working Memory ◽  
Instrumental Music ◽  
Previous Experiment ◽  
Recognition Task ◽  
Stimulus Presentation ◽  
False Alarms ◽  
Men And Women ◽  
Male And Female ◽  
Female Voices ◽  
The Voice

The aim of this study was examined the ability to identify voices of unfamiliar people. In experiment 1, participants performed tried to recognize the voice of unfamiliar man or woman. Results showed that subjects generally matched 83.11% when the target voice was present and made 56.45% false alarms when it was not. Discrimination was different from chance and subjects used liberal response criteria. In experiment 2, men and women tried to identify the same voices of men and women as in previous experiment. Between stimulus presentation and the recognition task, subjects listened instrumental music for 2.38 minutes, with the aim of making it harder that the voice remain active in working memory. Results showed that ability of men and women to identify an unfamiliar voice was null, in both cases with liberal response criterion. Men matched 12.06%, with 65.51% false alarms, and women 25.80% and 56.45% respectively. There was no differences in the ability to identify male and female voices, although women tend to choose more than men, even when no target voice was present.

scholarly journals The rapid synthesis of integral stimuli

2021 ◽  
Author(s):  
Andy Wills ◽  
Charlotte E R Edmunds ◽  
Fraser Milton
Keyword(s):  
Time Pressure ◽  
Stimulus Presentation ◽  
Rapid Synthesis ◽  
Single Dimension ◽  
Combination Theory ◽  
Presentation Time

Integral stimuli (e.g. colours varying in saturation and brightness) are classically considered to be processed holistically (i.e. as undifferentiated stimulus wholes); people analyze such stimuli into their consistent dimensions only with substantial time, effort, training, or instruction (Foard & Kemler Nelson, 1984). In contrast, Combination Theory (Wills et al., 2015) argues that the dimensions of integral stimuli are quickly combined. Through an investigation of the effects of time pressure, we support Combination Theory over the classical holistic-to-analytic account. Specifically, using colored squares varying in saturation and brightness, we demonstrate that the prevalence of single-dimension classification increases as stimulus presentation time is reduced. We conclude that integral stimuli are not slowly analyzed, they are quickly synthesized.

scholarly journals Eye Movement Dynamics Differ between Encoding and Recognition of Faces

Vision ◽  
2019 ◽  
Vol 3 (1) ◽  
pp. 9 ◽  
Author(s):  
Joseph M. Arizpe ◽  
Danielle L. Noles ◽  
Jack W. Tsao ◽  
Annie W.-Y. Chan
Keyword(s):  
Eye Movements ◽  
Recognition Performance ◽  
Spatial Dynamics ◽  
Stimulus Presentation ◽  
Study Phase ◽  
Facial Identity ◽  
Movement Dynamics ◽  
Presentation Time ◽  
Optimal Encoding ◽  
Feature Information

Facial recognition is widely thought to involve a holistic perceptual process, and optimal recognition performance can be rapidly achieved within two fixations. However, is facial identity encoding likewise holistic and rapid, and how do gaze dynamics during encoding relate to recognition? While having eye movements tracked, participants completed an encoding (“study”) phase and subsequent recognition (“test”) phase, each divided into blocks of one- or five-second stimulus presentation time conditions to distinguish the influences of experimental phase (encoding/recognition) and stimulus presentation time (short/long). Within the first two fixations, several differences between encoding and recognition were evident in the temporal and spatial dynamics of the eye-movements. Most importantly, in behavior, the long study phase presentation time alone caused improved recognition performance (i.e., longer time at recognition did not improve performance), revealing that encoding is not as rapid as recognition, since longer sequences of eye-movements are functionally required to achieve optimal encoding than to achieve optimal recognition. Together, these results are inconsistent with a scan path replay hypothesis. Rather, feature information seems to have been gradually integrated over many fixations during encoding, enabling recognition that could subsequently occur rapidly and holistically within a small number of fixations.

Indicating the Singular Point in First-Order Optical Flow Fields

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 80-80
Author(s):  
A M L Kappers ◽  
S F Te Pas ◽  
J J Koenderink ◽  
J Dentener
Keyword(s):  
Singular Point ◽  
Flow Field ◽  
Optical Flow ◽  
Stimulus Presentation ◽  
Singular Points ◽  
First Order ◽  
Optical Flow Field ◽  
Visible Part ◽  
Presentation Time ◽  
Random Dot Patterns

We investigated the accuracy with which subjects can indicate the singular point in a first-order optical flow field. This singular point might be important in navigation and orientation. The stimuli were expanding or rotating sparse random-dot patterns consisting of 80 dark dots on a light background. The stimulus window was circular with a diameter of 20 deg arc. The singular point could be at one of 48 different locations. Subjects had to indicate the location of this singular point with a cursor, while fixating in the centre of the stimulus. Presentation time was unlimited, though each dot had a limited lifetime (114 ms) to avoid density cues. Both veridicality and reproducibility for our subjects increased with increasing values of expansion or rotation in a nonlinear way. We did not find any systematic differences between expansion and rotation. When we blocked either the outer rim or the central part of the stimulus, performance remained the same for singular points that were within the visible part of the stimulus. For singular points outside this visible part, the reproducibility also remained the same, but subjects tended to locate the singular points closer to the rim of the visible part of the stimulus.

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