Related Experiment Video
Updated: Oct 16, 2025
05:39
Generating Strictly Controlled Stimuli for Figure Recognition Experiments
Published on: March 18, 2019
5.4K
Nonsymbolic numerosity in sets with illusory-contours exploits a context-sensitive, but contrast-insensitive, visual
Andrea Adriano1, Luca Rinaldi2,3, Luisa Girelli4,5
1Department of Psychology, University of Milano-Bicocca, Piazza dell'Ateneo Nuovo 1, Edificio U6, 20126, Milano, Italy. andrea.adriano@hotmail.com.
Attention, Perception & Psychophysics
|October 18, 2021
Summary
Illusory contours (ICs) cause underestimation of visual numerosity, but this effect is independent of brightness changes. This suggests that boundary formation, not brightness, drives numerosity processing via discrete visual inputs.
Area of Science:
- Cognitive Psychology
- Visual Perception
- Numerical Cognition
Background:
- Approximate numerical representation is debated due to confounding sensory cues.
- Illusory contours (ICs) previously suggested numerosity processing relies on discrete input.
- Prior studies confounded ICs with illusory brightness, a potential continuous sensory confound.
Purpose of the Study:
- To investigate if illusory brightness or boundary formation drives numerosity underestimation.
- To isolate the effect of ICs on numerosity independent of brightness changes.
- To determine if numerosity processing relies on discrete visual input.
Main Methods:
- Participants performed a numerical discrimination task.
- Manipulated alignment and contrast polarity of open/closed inducers to create ICs.
- Experiment 1: Single-polarity inducers (brightness change).
- Experiment 2: Opposite-polarity inducers (minimal brightness change).
- Experiment 3: Closed inducers preventing IC completion.
Main Results:
- Numerosity underestimation due to ICs was observed in Experiments 1 and 2.
- This underestimation was independent of inducer contrast polarity (brightness).
- No underestimation occurred when ICs were prevented (Experiment 3).
Conclusions:
- Illusory brightness enhancement is not the primary cause of IC-induced numerosity underestimation.
- A contrast-polarity-insensitive boundary formation mechanism likely drives the effect.
- Findings support the hypothesis that numerosity processing utilizes discrete visual inputs.
More Related Videos
Related Concept Videos
01:21Gestalt Principles of Perception
641
Gestalt principles provide a framework for understanding how humans perceive objects as unified wholes within their context. These principles are essential in explaining the cognitive processes that make sense of complex visual stimuli by organizing them into coherent groups. One fundamental principle is proximity, which posits that objects located close to each other are perceived as a collective group. For instance, when dots are positioned near one another, the visual system interprets them...
641
01:12Perceptual Constancy
697
Perceptual constancy is the ability to recognize that objects remain consistent and unchanged even when their appearance varies due to changes in sensory input. There are four main types of perceptual constancy: size constancy, shape constancy, color constancy, and brightness constancy.
Size constancy is the recognition that an object remains the same size, even when its image on the retina changes. For instance, a bus is perceived to be large enough to carry people, even if it looks tiny from...
Size constancy is the recognition that an object remains the same size, even when its image on the retina changes. For instance, a bus is perceived to be large enough to carry people, even if it looks tiny from...
697
01:12Visual Agnosia
457
Visual agnosia is a condition characterized by the inability to recognize visually presented objects despite having normal vision. For instance, a person with visual agnosia can describe the shape and color of an object but cannot identify or name it. This impairment does not affect their visual field, acuity, color vision, brightness discrimination, language, or memory. An example of this condition in a social setting is someone at a dinner party asking for "that silver thing with a round...
457
01:29Non-Verbal Cues
43
Non-verbal communication extends beyond gestures and facial expressions to include vocal elements known as paralanguage. Paralanguage consists of non-verbal vocal cues such as pitch, loudness, speech rate, pauses, and non-verbal vocalizations like laughter, sighs, and moans. These elements not only accompany speech but also provide critical emotional and contextual information.The Role of Paralanguage in CommunicationParalanguage adds depth to spoken language by conveying emotions and...
43
01:15Depth Perception and Spatial Vision
1.2K
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.
1.2K
01:05Difference from Background: Limit of Detection
7.4K
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...
7.4K