Neural Substrates for Early Data Reduction in Fast Vision: A Psychophysical Investigation.

To ensure survival, the visual system must rapidly extract the most important elements from a large stream of information. This necessity clashes with the computational limitations of the human brain, so a strong early data reduction is required to efficiently process information in fast vision. A theoretical early vision model, recently developed to preserve maximum information using minimal computational resources, allows efficient image data reduction by extracting simplified containing only optimally informative, salient features.

Effectiveness of labels in digital art experience: psychophysiological and behavioral evidence.

Introduction: Nowadays museums make large use of digital materials (e.g., virtual tours) to attract visitors.

Saccadic trajectories deviate toward or away from optimally informative visual features.

The saccades' path is influenced by visual distractors, making their trajectory curve or them. Previous research suggested that the more salient the distractor, the more pronounced is the curvature. We investigate the saliency of spatial visual features, predicted by a constrained maximum entropy model to be optimal or non-optimal information carriers in fast vision, by using them as distractors in a saccadic task.

Time estimation during motor activity.

Several studies on time estimation showed that the estimation of temporal intervals is related to the amount of attention devoted to time. This is explained by the scalar timing theory, which assumes that attention alters the number of pulses transferred by our internal clock to an accumulator that keeps track of the elapsed time. In a previous study, it was found that time underestimation during cognitive-demanding tasks was more pronounced while walking than while sitting, whereas no clear motor-induced effects emerged without a concurrent cognitive task.

Psychophysiological and behavioral responses to descriptive labels in modern art museums.

Educational tools in art exhibitions seem crucial to improve the cultural and aesthetic experience, particularly of non-expert visitors, thus becoming a strategic goal for museums. However, there has not been much research regarding the impact of labels on the quality of visitors' aesthetic experience. Therefore, here we compared the impact on the cognitive and emotional experience of naïve visitors between essential and descriptive labels, through multiple objective and subjective measurements, focusing on the controversial modern art museum context.

Fast discrimination of fragmentary images: the role of local optimal information.

In naturalistic conditions, objects in the scene may be partly occluded and the visual system has to recognize the whole image based on the little information contained in some visible fragments. Previous studies demonstrated that humans can successfully recognize severely occluded images, but the underlying mechanisms occurring in the early stages of visual processing are still poorly understood. The main objective of this work is to investigate the contribution of local information contained in a few visible fragments to image discrimination in fast vision.

Florence "blues" are clothed in triple basic terms.

Psycholinguistic studies provide evidence that Italian has more than one basic color term (BCT) for "blue": consensually, denotes "dark blue," while "light-and-medium blue," with diatopic variation, is termed either or . For Tuscan speakers (predominantly from Florence), the BLUE area is argued to linguistically differentiate between "medium blue" and "light blue." We scrutinized "basicness" of the three terms.

Information-optimal local features automatically attract covert and overt attention.

In fast vision, local spatial properties of the visual scene can automatically capture the observer's attention. We used specific local features, predicted by a constrained maximum-entropy model to be optimal information-carriers, as candidate "salient features''. Previous studies showed that participants choose these optimal features as "more salient" if explicitly asked.

Influence of Motor and Cognitive Tasks on Time Estimation.

The passing of time can be precisely measured by using clocks, whereas humans' estimation of temporal durations is influenced by many physical, cognitive and contextual factors, which distort our internal clock. Although it has been shown that temporal estimation accuracy is impaired by non-temporal tasks performed at the same time, no studies have investigated how concurrent cognitive and motor tasks interfere with time estimation. Moreover, most experiments only tested time intervals of a few seconds.

Pupil responses to implied motion in figurative and abstract paintings.

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).

Pupillary response to real, illusory, and implied motion.

The perception of moving objects (real motion) is a critical function for interacting with a dynamic environment. Motion perception can be also induced by particular structural features of static images (illusory motion) or by photographic images of subjects in motion (implied motion, IM). Many cortical areas are involved in motion processing, particularly the medial temporal cortical area (MT), dedicated to the processing of real, illusory, and implied motion.

Early Visual Saliency Based on Isolated Optimal Features.

Under fast viewing conditions, the visual system extracts salient and simplified representations of complex visual scenes. Saccadic eye movements optimize such visual analysis through the dynamic sampling of the most informative and salient regions in the scene. However, a general definition of saliency, as well as its role for natural active vision, is still a matter for discussion.

Pupillary response to representations of light in paintings.

It is known that, although the level of light is the primary determinant of pupil size, cognitive factors can also affect pupil diameter. It has been demonstrated that photographs of the sun produce pupil constriction independently of their luminance and other low-level features, suggesting that high-level visual processing may also modulate pupil response. Here, we measure pupil response to artistic paintings of the sun, moon, or containing a uniform lighting, that, being mediated by the artist's interpretation of reality and his technical rendering, require an even higher level of interpretation compared with photographs.

Motion perception deficit in Down Syndrome.

It is a well established fact that Down Syndrome (DS) individuals have a tendency to develop Alzheimer's disease (AD) (Lott, I.T., Head, E.

Anti-Glass patterns and real motion perception: same or different mechanisms?

A sequence of anti-Glass patterns, composed by dot pairs with opposite luminance polarity, elicits a clear perception of motion in the direction of the white dot of the pair. This effect can be reversed by introducing a delay in the presentation of white dots, suggesting a faster processing of light dots as a cause of the motion signal (M. M.

Visual spatial integration in the elderly.

Purpose: To investigate the effect of ageing on contour integration in subjects whose ages ranged from 20 to 99 years.

Methods: Detection thresholds were measured for a closed chain of Gabor patches oriented tangentially to a circle (target) embedded in a background of randomly positioned and oriented Gabors (noise). Detection thresholds were measured for different distances of elements composing the target.

Powerful motion illusion caused by temporal asymmetries in ON and OFF visual pathways.

Successive presentations of Glass patterns (randomly positioned pairs of dots oriented in a coherent pattern) create a strong sense of global motion along the orientation of the pattern, but ambiguous in direction. Here we report that dynamic "anti-Glass" patterns, created by successive pairs of globally structured pairs of opposite polarity, create an even more powerful motion illusion that is unambiguous in direction: the dark dots always move toward the light. The motion can be cancelled and reversed by introducing a real delay in the presentation of the light dots, suggesting that the effective stimulation of the light is about 3 ms faster than the dark dots.

Spatial and motion integration in children with autism.

Neuropsychological and psychophysical studies report controversial results regarding local-global visual processing and motion perception in autism. Here, we investigate contour integration and motion perception in an accurately diagnosed sample of autistic children, using low-level psychophysical tasks. We measured detection thresholds for a closed chain of Gabor patches, for different values of inter-element distance and we measured coherency thresholds of optic flow motion stimuli.

Agnosia for global patterns: When the cross-talk between grouping and visual selective attention failS.

We present a single case study of a 72-year-old mild AD patient, MC, with a highly specific deficit in deriving the global pattern of visual stimuli, in the absence of visuospatial neglect. MC shows a specific difficulty in segregating overlapping figures, in object decision, and in all neuropsychological tasks requiring perception of a global structure from local cues, such as the Street Completion Test and the perception of illusory contours and of the global level of hierarchical stimuli. The detailed neuropsychological assessment prompted a psychophysical experiment aiming to quantify the limits of perceptual grouping in MC.