Related Experiment Video
Updated: Jul 3, 2026
13:00
Measuring Attention and Visual Processing Speed by Model-based Analysis of Temporal-order Judgments
Published on: January 23, 2017
Spatial and temporal influences on the contrast gauge.
1Department of Psychology, Bucknell University, O'Leary Center, Lewisburg, PA 17837, USA; Program in Neuroscience, Bucknell University, Lewisburg, PA 17837, USA. shapiro@bucknell.edu
Vision Research
|July 31, 2008
Summary
The perceptual divider in a contrast gauge shifts based on surround luminance. Its position can indicate zero luminance contrast under specific conditions, but it
Area of Science:
- Visual Perception
- Psychophysics
- Image Analysis
Background:
- A contrast gauge uses a shaded bar where the perceived division between dark and light shifts with surround luminance.
- This perceptual shift is influenced by surround characteristics like luminance, width, chromaticity, and temporal modulation.
Purpose of the Study:
- To investigate if the perceptual division in a contrast gauge can accurately indicate zero luminance contrast.
- To explore how various surround properties affect the contrast gauge's indicator settings.
Main Methods:
- Three observers adjusted a contrast gauge indicator while viewing a bar surrounded by a temporally modulated field.
- Experiments varied modulation amplitude, chromaticity (RGBW), temporal frequency, and surround width (narrow to 12.5 degrees).
Main Results:
- Observer settings linearly tracked modulation amplitude changes.
- Zero luminance contrast was indicated when the surround was wide (12.5deg), modulated ≤1Hz, and had white or green chromaticity.
- Narrow surrounds, faster modulation (>1Hz), or red/blue chromaticity did not yield accurate zero contrast settings.
Conclusions:
- The contrast gauge indicator is not a simple measure of luminance contrast, being influenced by multiple perceptual processes.
- Surround size suggests that perceived contrast involves multi-scale spatial processing.
- High spatial frequencies may dominate perception, potentially down-weighting low spatial frequency contrast information.
Related Concept Videos
01:15Depth Perception and Spatial Vision
Depth perception is the ability to perceive objects three-dimensionally. It relies on two types of cues: binocular and monocular. Binocular cues depend on the combination of images from both eyes and how the eyes work together. Since the eyes are in slightly different positions, each eye captures a slightly different image. This disparity between images, known as binocular disparity, helps the brain interpret depth. When the brain compares these images, it determines the distance to an object.
01:25Factors Affecting Perception
Perception is influenced by perceptual set, context, motivation, and emotion. Perceptual set, or perceptual expectancy, refers to the tendency to perceive things in a particular way, influenced by previous experiences and expectations. This phenomenon affects the interpretation of stimuli, creating a set of mental tendencies and assumptions that impact sensory perceptions of sound, taste, touch, and sight.
An illustrative example of a perceptual set is the scenario where an airline pilot told...
An illustrative example of a perceptual set is the scenario where an airline pilot told...
01:20Pressure Gauges
Most pressure gauges, like those on scuba tanks, are calibrated to read zero at atmospheric pressure. Readings from such gauges are called the gauge pressure, which is the pressure relative to atmospheric pressure. When the pressure inside the tank exceeds atmospheric pressure, the gauge reports a positive value. Some gauges are designed to measure negative pressure. For example, many physics experiments must take place in a vacuum chamber, a rigid chamber from which some of the air is pumped...
01:05Difference from Background: Limit of Detection
The limit of detection (LOD) is the smallest amount of analyte that can be distinguished from the background noise. The LOD value corresponds to the concentration at which the analyte signal is three times larger than the standard deviation of the blank signal. Below this value, the analyte signal cannot be differentiated from the background noise. It is calculated by dividing the calibration slope by 3 times the standard deviation of the blank signals.
The LOD indicates the presence or absence...
The LOD indicates the presence or absence...
01:17Sound as Pressure Waves
Sound waves, which are longitudinal waves, can be modeled as the displacement amplitude varying as a function of the spatial and temporal coordinates. As a column of the medium is displaced, its successive columns are also displaced. As the successive displacements differ relatively, a pressure difference with the surrounding pressure is created. The gauge pressure varies across the medium.
The pressure fluctuation depends on the difference in displacements between the successive points in the...
The pressure fluctuation depends on the difference in displacements between the successive points in the...
01:26Influence of Earth's Curvature and Atmospheric Refraction on Leveling
During leveling, the Earth's curvature and atmospheric refraction introduce deviations in the line of sight from a true horizontal reference. When the line of sight is leveled, it remains perpendicular to the plumb line only at a single point. Beyond this, it deviates due to the Earth’s curvature, represented by the correction C. For a sight distance D, the deviation can be derived using the relationship:This relationship shows that the deviation increases quadratically with distance. Over a...