Visual size analysers and Mueller-Lyer illusions.

C Bonciocat; M Jemna; L Petrescu

PubMed · 6417697

Visual size analysers and Mueller-Lyer illusions.

Abstract

The characteristics of the structural components inducing a length distortion were studied in Mueller-Lyer configuration and in other similar or different configurations. When placed in a more central position both ingoing and outgoing fins induced an apparent shrinkage of the shaft. It was found that a comparable effect is obtained as well with perpendicular lines and various other forms placed slightly centrally from the ends of the shaft (when placed away from the ends, an elongation is obtained). The shrinkage effect depended primarily on the ratio of the inner extent defined by the inducing forms to the extent of the shaft. With perpendicular inducing lines the most pronounced effects were observed at ratios of about 3/4. Configurations containing instead of perpendicular lines angled fins in equivalent positions showed a slightly more pronounced effect for the ingoing fins and less pronounced for the outgoing fins with a shift of optimal positions towards the ends for the ingoing and towards the center for the outgoing fins. If the ends of the shaft are marked by vertical lines the effect of the inducing forms is drastically reduced; it becomes significant as they exceed in vertical extent the end vertical lines. The findings support the idea of an interaction between size detectors as a basis of the length distorsion associated to Mueller-Lyer and other related configurations.

Explore related subjects

Form Perception Humans Illusions Optical Illusions Size Perception Visual Perception Journal Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

C Bonciocat, M Jemna, L Petrescu. Visual size analysers and Mueller-Lyer illusions.. https://pubmed.ncbi.nlm.nih.gov/6417697/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Absence of flash-lag when judging global shape from local positions.

When a flash is presented aligned with a moving stimulus, the former is perceived to lag behind the latter (the flash-lag effect). We study whether this mislocalization occurs when a positional judgment is not required, but a veridical spatial relationship between moving and flashed stimuli is needed to perceive a global shape. To do this, we used Glass patterns that are formed by pairs of correlated dots. One dot of each pair was presented moving and, at a given moment, the other dot of each pair was flashed in order to build the Glass pattern. If a flash-lag effect occurs between each pair of dots, we expect the best perception of the global shape to occur when the flashed dots are presented before the moving dots arrive at the position that physically builds the Glass pattern. Contrary to this, we found that the best detection of Glass patterns occurred for the situation of physical alignment. This result is not consistent with a low-level contribution to the flash-lag effect.

Form Perception↗

PubMed2006

Object recognition and segmentation by a fragment-based hierarchy.

How do we learn to recognize visual categories, such as dogs and cats? Somehow, the brain uses limited variable examples to extract the essential characteristics of new visual categories. Here, I describe an approach to category learning and recognition that is based on recent computational advances. In this approach, objects are represented by a hierarchy of fragments that are extracted during learning from observed examples. The fragments are class-specific features and are selected to deliver a high amount of information for categorization. The same fragments hierarchy is then used for general categorization, individual object recognition and object-parts identification. Recognition is also combined with object segmentation, using stored fragments, to provide a top-down process that delineates object boundaries in complex cluttered scenes. The approach is computationally effective and provides a possible framework for categorization, recognition and segmentation in human vision.

Form Perception↗

PubMed2006

Dynamics of shape interaction in human vision.

Spatial context can alter perceived shape, and temporal context can influence the perception of a stimulus. We sought to determine the time course of shape interactions by using a paradigm in which closed shape contours are laterally displaced over space and time. Target and masks are separated by various stimulus onset asynchrony (SOA) values, yielding forward, backward, and simultaneous masking conditions. Results indicate that spatial lateral interactions of shape are amplified by temporal asynchrony, reaching a peak at SOAs of 80-110 ms. Mask amplitude scales all effects and masking is shape specific. When a single mask follows the target, both spatial configuration and mask onset transient are critical in determining depth of masking. When the target is followed by two sequential masks, the possibility of apparent motion determines whether one or both masks drive masking. These findings suggest that temporal interactions of shape are dependent on an interactive combination of shape specificity and transients, that apparent motion plays a modulatory role, and that target shape is determined after a temporal window, not at its onset.

Form Perception↗