Discrimination and Detection of Changes in the Velocity of Visual Motion: Effect of Aperture Size

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 239-239
Author(s):  
L Likova ◽  
G Dimitrov ◽  
S Mateeff ◽  
J Hohnsbein
Keyword(s):  
Change Detection ◽  
Discrimination Task ◽  
Critical Frequency ◽  
Visual Motion ◽  
Critical Factor ◽  
Detection Task ◽  
Viewing Distance ◽  
Aperture Size ◽  
Mean Velocity ◽  
The Subject

Recently Mateeff and Hohnsbein (1996 Vision Research36 2873 – 2882) showed that the critical frequency for detection of modulated velocity of motion was invariant with respect to the viewing distance. The critical frequency was a function of the ratio between the mean velocity and the size of the aperture through which the motion was observed. In the present study we examined whether the velocity/aperture ratio affects velocity discrimination and detection of single velocity changes. Six subjects observed a random-dot pattern that could move within an invisible square aperture. In the discrimination task, two motions of 250 ms duration with slightly different velocities were presented with a 1 s interval between them. The subject had to report which of the motions was faster. In the change-detection task the same two motions were presented without an interval between them and the subject had to report whether the change was from a low to a high velocity or vice versa. Mean velocities of 8 and 64 deg s−1 and aperture sizes of 10 and 40 deg were employed in both tasks. Weber fractions were determined by the method of constant stimuli. The discrimination accuracy was not affected by aperture size at either mean velocity. The detection task was also unaffected by aperture size at 8 deg s−1. However, at 64 deg s−1 decreasing aperture size impaired the Weber fractions by a factor of about three. We suggest that the decrease of the lifetime of the dots of the pattern at high velocities and small apertures may be the critical factor for the impairment of the change detection. This factor is of less importance for the velocity discrimination task.

Vivid Imagers Are Better at Detecting Salient Changes

2006 ◽  
Vol 27 (4) ◽  
pp. 218-228 ◽  
Author(s):  
Paul Rodway ◽  
Karen Gillies ◽  
Astrid Schepman
Keyword(s):  
Individual Differences ◽  
Change Detection ◽  
Visual Imagery ◽  
Detection Task ◽  
Level Of Detail ◽  
Detection Accuracy ◽  
Change Detection Task ◽  
Term Change ◽  
High Level

This study examined whether individual differences in the vividness of visual imagery influenced performance on a novel long-term change detection task. Participants were presented with a sequence of pictures, with each picture and its title displayed for 17  s, and then presented with changed or unchanged versions of those pictures and asked to detect whether the picture had been changed. Cuing the retrieval of the picture's image, by presenting the picture's title before the arrival of the changed picture, facilitated change detection accuracy. This suggests that the retrieval of the picture's representation immunizes it against overwriting by the arrival of the changed picture. The high and low vividness participants did not differ in overall levels of change detection accuracy. However, in replication of Gur and Hilgard (1975) , high vividness participants were significantly more accurate at detecting salient changes to pictures compared to low vividness participants. The results suggest that vivid images are not characterised by a high level of detail and that vivid imagery enhances memory for the salient aspects of a scene but not all of the details of a scene. Possible causes of this difference, and how they may lead to an understanding of individual differences in change detection, are considered.

An attentional bias for LEGO® people using a change detection task: Are LEGO® people animate?

2016 ◽  
Vol 70 (3) ◽  
pp. 219-231 ◽  
Author(s):  
Mitchell R. P. LaPointe ◽  
Rachael Cullen ◽  
Bianca Baltaretu ◽  
Melissa Campos ◽  
Natalie Michalski ◽  
...  
Keyword(s):  
Change Detection ◽  
Attentional Bias ◽  
Detection Task ◽  
Change Detection Task

Inflow Measurement in a Tidal Strait for Deploying Tidal Current Turbines: Lessons, Opportunities and Challenges

2010 ◽  
Author(s):  
Ye Li ◽  
Jonathan A. Colby ◽  
Neil Kelley ◽  
Robert Thresher ◽  
Bonnie Jonkman ◽  
...  
Keyword(s):  
Tidal Current ◽  
Laboratory Tests ◽  
Critical Factor ◽  
Tidal Energy ◽  
Background Information ◽  
Commercial Development ◽  
Mean Velocity ◽  
Topic Area ◽  
East River ◽  
Turbine Performance

Tidal energy has received increasing attention over the past decade. This increasing focus on capturing the energy from tidal currents has brought about the development of many designs for tidal current turbines. Several of these turbines are progressing rapidly from design to prototype and pre-commercial stages. As these systems near commercial development, it becomes increasingly important that their performance be validated through laboratory tests (e.g., towing tank tests) and sea tests. Several different turbine configurations have been tested recently. The test results show significant differences in turbine performance between laboratory tests, numerical simulations, and sea tests. Although the mean velocity of the current is highly predictable, evidence suggests a critical factor in these differences is the unsteady inflow. To understand the physics and the effect of the inflow on turbine performance and reliability, Verdant Power (Verdant) and the National Renewable Energy Laboratory (NREL) have engaged in a partnership to address the engineering challenges facing marine current turbines. As part of this effort, Verdant deployed Acoustic Doppler Current Profiler (ADCP) equipment to collect data from a kinetic hydropower system (KHPS) installation at the Roosevelt Island Tidal Energy (RITE) project in the East River in New York City. The ADCP collected data for a little more than one year, and this data is critical for properly defining the operating environment needed for marine systems. This paper summarizes the Verdant-NREL effort to study inflow data provided by the fixed, bottom-mounted ADCP instrumentation and how the data is processed using numerical tools. It briefly reviews previous marine turbine tests and inflow measurements, provides background information from the RITE project, and describes the test turbine design and instrumentation setup. This paper also provides an analysis of the measured time domain data and a detailed discussion of shear profiling, turbulence intensity, and time-dependent fluctuations of the inflow. The paper concludes with suggestions for future work. The analysis provided in this paper will benefit future turbine operation studies. In addition, this study, as well as future studies in this topic area, will be beneficial to environmental policy makers and fishing communities.

scholarly journals LIP activity in the interstimulus interval of a change detection task biases the behavioral response

2015 ◽  
Vol 114 (5) ◽  
pp. 2637-2648 ◽  
Author(s):  
Fabrice Arcizet ◽  
Koorosh Mirpour ◽  
Daniel J. Foster ◽  
Caroline J. Charpentier ◽  
James W. Bisley
Keyword(s):  
Eye Movements ◽  
Change Detection ◽  
Behavioral Response ◽  
Interstimulus Interval ◽  
Detection Task ◽  
Covert Attention ◽  
Change Detection Task ◽  
Lateral Intraparietal Area ◽  
Overt Attention ◽  
The World

When looking around at the world, we can only attend to a limited number of locations. The lateral intraparietal area (LIP) is thought to play a role in guiding both covert attention and eye movements. In this study, we tested the involvement of LIP in both mechanisms with a change detection task. In the task, animals had to indicate whether an element changed during a blank in the trial by making a saccade to it. If no element changed, they had to maintain fixation. We examine how the animal's behavior is biased based on LIP activity prior to the presentation of the stimulus the animal must respond to. When the activity was high, the animal was more likely to make an eye movement toward the stimulus, even if there was no change; when the activity was low, the animal either had a slower reaction time or maintained fixation, even if a change occurred. We conclude that LIP activity is involved in both covert and overt attention, but when decisions about eye movements are to be made, this role takes precedence over guiding covert attention.

Chunking by social relationship in working memory

2021 ◽  
Author(s):  
Ilenia Paparella ◽  
Liuba Papeo
Keyword(s):  
Working Memory ◽  
Change Detection ◽  
Secondary Task ◽  
Social Relationship ◽  
Social Groups ◽  
Detection Task ◽  
Change Detection Task ◽  
Face To Face ◽  
Meaningful Interaction ◽  
Probe Array

Working memory (WM) uses knowledge and relations to organize and store multiple individual items in a smaller set of structured units, or chunks. We investigated whether a crowd of individuals that exceeds the WM is retained and, therefore, recognized more accurately, if individuals are represented as interacting with one another –i.e., they form social chunks. Further, we asked what counts as a social chunk in WM: two individuals involved in a meaningful interaction or just spatially close and face-to-face. In three experiments with a delayed change-detection task, participants had to report whether a probe-array was the same of, or different from a sample-array featuring two or three dyads of bodies either face-to-face (facing array) or back-to-back (non-facing array). In Experiment 1, where facing dyads depicted coherent, meaningful interactions, participants were more accurate to detect changes in facing (vs. non-facing) arrays. A similar advantage was found in Experiment 2, even though facing dyads depicted no meaningful interaction. In Experiment 3, we introduced a secondary task (verbal shadowing) to increase WM load. This manipulation abolished the advantage of facing (vs. non-facing) arrays, only when facing dyads depicted no meaningful interactions. These results show that WM uses representation of interaction to chunk crowds in social groups. The mere facingness of bodies is sufficient on its own to evoke representation of interaction, thus defining a social chunk in WM; although the lack of semantic anchor makes chunking fainter and more susceptible to interference of a secondary task.

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