Globally Perceived Directional Flow in Static Images

Perception ◽  
1989 ◽  
Vol 18 (2) ◽  
pp. 155-172 ◽  
Author(s):  
Bart Farell ◽  
Bela Julesz
Keyword(s):  
Visual Space ◽  
Stimulus Location ◽  
Visual Sensitivity ◽  
Global Processing ◽  
Directional Information ◽  
Spatial Direction ◽  
Directional Flow ◽  
Long Range Interactions ◽  
Static Images ◽  
Component Stimulus

Visual sensitivity to spatial direction has classically been associated with motion perception. Yet humans are adept at deriving directional information in the absence of motion, as when they read maps, or follow arrows or animal tracks. Experiments are reported on the perception of parallel arrow-like forms in which a specific visual sensitivity to static direction is demonstrated. Global processing is operationally defined in terms of the relative discriminability of sets and subsets of stimulus elements; a set of parallel elements and a set in which one element is antiparallel to the rest are shown to be processed globally. The result of this global processing is a static analog of unidirectional optic flow. Global spatial direction differs fundamentally from other perceptions derived from static image processing. It involves long-range interactions in texture arrays, it does not carry information about stimulus location, and it is not reducible to the perception of component stimulus elements. Its likely function is in the construction of the layout of visual space.

scholarly journals Pupil responses to implied motion in figurative and abstract paintings

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258490
Author(s):  
Serena Castellotti ◽  
Lisa Scipioni ◽  
Stefano Mastandrea ◽  
Maria Michela Del Viva
Keyword(s):  
Pupil Size ◽  
Aesthetic Experience ◽  
Pupillary Response ◽  
Motion Blur ◽  
Motion Processing ◽  
Top Down ◽  
Directional Information ◽  
Implied Motion ◽  
Visual Motion Processing ◽  
Static Images

Motion can be perceived in static images, such as photos and figurative paintings, representing realistic subjects in motion, with or without directional information (e.g., motion blur or speed lines). Motion impression can be achieved even in non-realistic static images such as motion illusions and abstract paintings. It has been shown that visual motion processing affects the diameter of the pupil, responding differently to real, illusory, and implied motion in photographs (IM). It has been suggested that these different effects might be due to top-down modulations from different cortical areas underlying their processing. It is worthwhile to investigate pupillary response to figurative paintings, since they require an even higher level of interpretation than photos representing the same kind of subjects, given the complexity of cognitive processes involved in the aesthetic experience. Also, pupil responses to abstract paintings allows to study the effect of IM perception in representations devoid of real-life motion cues. We measured pupil responses to IM in figurative and abstract artworks depicting static and dynamic scenes, as rated by a large group of individuals not participating in the following experiment. Since the pupillary response is modulated by the subjective image interpretation, a motion rating test has been used to correct individual pupil data according to whether participants actually perceived the presence of motion in the paintings. Pupil responses to movies showing figurative and abstract subjects, and to motion illusions were also measured, to compare real and illusory motion with painted IM. Movies, both figurative and abstract, elicit the largest pupillary dilation of all static stimuli, whereas motion illusions cause the smallest pupil size, as previously shown. Interestingly, pupil responses to IM depend on the paintings’ style. Figurative paintings depicting moving subjects cause more dilation than those representing static figures, and pupil size increases with the strength of IM, as already found with realistic photos. The opposite effect is obtained with abstract artworks. Abstract paintings depicting motion produce less dilation than those depicting stillness. In any case, these results reflect the individual subjective perception of dynamism, as the very same paintings can induce opposite responses in observer which interpreted it as static or dynamic. Overall, our data show that pupil size depends on high-level interpretation of motion in paintings, even when they do not represent real-world scenes. Our findings further suggest that the pupil is modulated by multiple top-down cortical mechanisms, involving the processing of motion, attention, memory, imagination, and other cognitive functions necessary for enjoying a complete aesthetic experience.

scholarly journals Effects of Aging on the Encoding of Spatial Direction in the Human Brain

2019 ◽  
Author(s):  
Christoph Koch ◽  
Shu-Chen Li ◽  
Thad A. Polk ◽  
Nicolas W. Schuck
Keyword(s):  
Older Adults ◽  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Age Differences ◽  
Spatial Navigation ◽  
Activation Patterns ◽  
Directional Information ◽  
Spatial Direction ◽  
Age Related ◽  
Pattern Similarity

AbstractHuman aging is characterized by impaired spatial cognition and reductions in the distinctiveness of category-specific fMRI activation patterns. Yet, little is know about age-related decline in neural distinctiveness of spatial information. Here, we asked whether neural tuning functions of walking direction are broadened in older versus younger adults. To test this idea, we developed a novel method that allowed us to investigate changes in fMRI-measured pattern similarity while participants navigated in different directions in a virtual spatial navigation task. We expected that directional tuning functions would be broader in older adults, and thus activation patterns that reflect neighboring directions would be less distinct as compared to non-adjacent directions. Because loss of distinctiveness leads to more confusions when information is read out by downstream areas, we analyzed predictions of a decoder trained on these representations and asked (1) whether decoder confusions between two directions increase proportionally to their angular similarity, (2) and how this effect may differ between age groups. Evidence for tuning-function-like signals was found in the retrosplenial complex and primary visual cortex. Significant age differences in tuning width, however, were only found in the primary visual cortex, suggesting that less precise visual information could lead to worse directional signals in older adults. Yet, age differences in visual tuning were not related to behavior. Instead, directional information encoded in RSC correlated with memory on task. These results shed new light on neural mechanisms underling age-related spatial navigation impairments and introduce a novel approach to measure tuning specificity using fMRI.

scholarly journals Visual space curves before eye movements

2021 ◽  
Author(s):  
Ifedayo-Emmmanuel Adeyefa-Olasupo
Keyword(s):  
Eye Movements ◽  
Visual System ◽  
Eye Movement ◽  
Visual Processing ◽  
Mechanical Model ◽  
Visual Space ◽  
Visual Sensitivity ◽  
Visual World ◽  
Space Curves ◽  
Transient Error

Despite the incessant retinal disruptions that necessarily accompany eye movements, our percept of the visual world remains continuous and stable—a phenomenon referred to as spatial constancy. How the visual system achieves spatial constancy remains unclear despite almost four centuries worth of experimentation. Here I measured visual sensitivity at geometrically symmetric locations, observing transient sensitivity differences between them where none should be observed if cells that support spatial constancy indeed faithfully translate or converge. These differences, recapitulated by a novel neurobiological mechanical model, reflect an overriding influence of putative visually transient error signals that curve visual space. Intermediate eccentric locations likely to contain retinal disruptions are uniquely affected by curved visual space, suggesting that visual processing at these locations is transiently turned off before an eye movement, and with the gating off of these error signals, turned back on after an eye-movement— a possible mechanism underlying spatial constancy.

Long-range interactions modulate the contrast gain in the lateral geniculate nucleus of cats

1999 ◽  
Vol 16 (5) ◽  
pp. 943-956 ◽  
Author(s):  
FATIMA FELISBERTI ◽  
ANDREW M. DERRINGTON
Keyword(s):  
Receptive Field ◽  
Ganglion Cells ◽  
Suppressive Effect ◽  
Visual Sensitivity ◽  
Optimal Size ◽  
Retinal Ganglion ◽  
Contrast Gain ◽  
Central Spot ◽  
Classical Receptive Field ◽  
Long Range Interactions

In previous work, we have shown that sudden image displacements well outside the classical receptive field modulate the visual sensitivity of LGN relay cells. Here we report the effect of image displacements on the response versus contrast function. The stimuli consisted of a central spot of optimal size and polarity (contrast range: 3–98%), flashed alone or in the presence of a peripheral annulus (radii: 5–15 deg) containing a low spatial-frequency grating displaced at saccade-like velocities (shift). The most consistent effect of the shift on the response to a central spot was to reduce the responsiveness of Y relay cells and, to a lesser extent, of X relay cells. The reduction in responsiveness was primarily a divisive rather than a subtractive effect and could be modelled by assuming that a greater contrast was required to produce a given excitatory response. In the absence of a central spot, remote motion had inhibitory effects on the firing rates of the majority of relay cells, but its effect on retinal ganglion cells was mainly excitatory. When the shifting grating covered the classical receptive field and its periphery, facilitatory effects or suppressive effects, depending on the spatial phase of the pattern, were observed in both retinal and geniculate cells. Remote motion strongly suppresses the responsiveness of relay cells to stimuli within the classical receptive field. This suppressive effect involves intrageniculate processing and is primarily associated with a reduction in contrast gain. It is likely that shift suppression contributes to the loss of visual sensitivity observed in saccadic suppression.

Response and Reinforcement in Operant Audiometry

1987 ◽  
Vol 52 (3) ◽  
pp. 294-299 ◽  
Author(s):  
Michael A. Primus
Keyword(s):  
Operant Conditioning ◽  
Space Versus ◽  
Visual Space ◽  
Central Processing ◽  
Operant Discrimination ◽  
Conditioning Rate ◽  
Significant Difference ◽  
Simple Detection ◽  
Variable Success ◽  
Response Task

Variable success in audiometric assessment of young children with operant conditioning indicates the need for systematic examination of commonly employed techniques. The current study investigated response and reinforcement features of two operant discrimination paradigms with normal I7-month-old children. Findings indicated more responses prior to the onset of habituation when the response task was based on complex central processing skills (localization and coordination of auditory/visual space) versus simple detection. Use of animation in toy reinforcers resulted in more than a twofold increase in the number of subject responses. Results showed no significant difference in response conditioning rate or consistency for the response tasks and forms of reinforcement examined.

Editorial: Human motion perception, eye movements, and orientation in visual space

2000 ◽  
Vol 59 (2) ◽  
pp. 85-88 ◽  
Author(s):  
Rudolf Groner ◽  
Marina T. Groner ◽  
Kazuo Koga
Keyword(s):  
Eye Movements ◽  
Motion Perception ◽  
Visual Space ◽  
Human Motion

Focusing of Visuospatial Attention

2001 ◽  
Vol 15 (4) ◽  
pp. 256-274 ◽  
Author(s):  
Caterina Pesce ◽  
Rainer Bösel
Keyword(s):  
Reaction Times ◽  
Visual Space ◽  
Spatial Relation ◽  
Stimulus Onset ◽  
Visuospatial Attention ◽  
Task Demands ◽  
Time Interval ◽  
Behavioral Studies ◽  
Task Conditions ◽  
Simple Rt

Abstract In the present study we explored the focusing of visuospatial attention in subjects practicing and not practicing activities with high attentional demands. Similar to the studies of Castiello and Umiltà (e. g., 1990) , our experimental procedure was a variation of Posner's (1980) basic paradigm for exploring covert orienting of visuospatial attention. In a simple RT-task, a peripheral cue of varying size was presented unilaterally or bilaterally from a central fixation point and followed by a target at different stimulus-onset-asynchronies (SOAs). The target could occur validly inside the cue or invalidly outside the cue with varying spatial relation to its boundary. Event-related brain potentials (ERPs) and reaction times (RTs) were recorded to target stimuli under the different task conditions. RT and ERP findings showed converging aspects as well as dissociations. Electrophysiological results revealed an amplitude modulation of the ERPs in the early and late Nd time interval at both anterior and posterior scalp sites, which seems to be related to the effects of peripheral informative cues as well as to the attentional expertise. Results were: (1) shorter latency effects confirm the positive-going amplitude enhancement elicited by unilateral peripheral cues and strengthen the criticism against the neutrality of spatially nonpredictive peripheral cueing of all possible target locations which is often presumed in behavioral studies. (2) Longer latency effects show that subjects with attentional expertise modulate the distribution of the attentional resources in the visual space differently than nonexperienced subjects. Skilled practice may lead to minimizing attentional costs by automatizing the use of a span of attention that is adapted to the most frequent task demands and endogenously increases the allocation of resources to cope with less usual attending conditions.

Right-Hemisphere Specialization for Contour Grouping

2014 ◽  
Vol 61 (5) ◽  
pp. 331-339 ◽  
Author(s):  
Gregor Volberg
Keyword(s):  
Right Hemisphere ◽  
Contour Detection ◽  
Global Processing ◽  
Detection Accuracy ◽  
Frequency Spectra ◽  
Visual Hemifield ◽  
Spatial Frequencies ◽  
A Chain ◽  
The Right ◽  
Hemisphere Specialization

Previous studies often revealed a right-hemisphere specialization for processing the global level of compound visual stimuli. Here we explore whether a similar specialization exists for the detection of intersected contours defined by a chain of local elements. Subjects were presented with arrays of randomly oriented Gabor patches that could contain a global path of collinearly arranged elements in the left or in the right visual hemifield. As expected, the detection accuracy was higher for contours presented to the left visual field/right hemisphere. This difference was absent in two control conditions where the smoothness of the contour was decreased. The results demonstrate that the contour detection, often considered to be driven by lateral coactivation in primary visual cortex, relies on higher-level visual representations that differ between the hemispheres. Furthermore, because contour and non-contour stimuli had the same spatial frequency spectra, the results challenge the view that the right-hemisphere advantage in global processing depends on a specialization for processing low spatial frequencies.

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