Spared cognitive processing of visual oddballs despite delayed visual evoked potentials in patient with partial recovery of vision after 53years of blindness

AbstractWe examined the visual and cognitive functions of a 72-year-old subject, KP, who recovered his sight after 53years of visual deprivation. We used visual evoked potentials (VEPs) to pattern-reversal and motion-onset stimuli and cognitive responses (ERPs) during the oddball paradigm to assess the effect of long-term deprivation on a mature visual system. KP lost his sight at the age of 17years, and light projection onto his right retina was restored at 71years by a corneal implant. Nine months after sight recovery we recorded reproducible responses to all examined stimuli. The response to pattern reversal contained two P100-like peaks with the later peak being dominant and significantly delayed (260ms) when compared to the P100s of two control subjects, to whom the stimuli were adjusted in size and contrast to mimic KP’s vision. KP’s motion-onset VEPs to full-field and peripheral stimuli had a characteristic shape with a well-defined N2 peak; however, both peaks were significantly delayed (262 and 272ms) compared to control responses. Unlike the P100 and N2 peaks, which represent sensory detection, the P3b/P300 component of the ERP to a target event in the oddball paradigm was not further delayed. In spite of degraded vision and sensory deprivation lasting 53years, KP displayed reproducible responses to all reported stimuli. Long-term visual deprivation and retinal detachment degraded KP’s visual sensory processing, assessed by pattern-reversal and motion-onset VEPs, whereas the cognitive processing of appropriate visual stimuli was not compromised

Constraints as an organizing principle of perception

Human visual perception is far from being an exact copy of reality. For the observer, it is much more important to dispose of relevant and immediately usable information. In fact, the accuracy allowing the safe interactions through the environment is sufficient. The perception always mirrors the life style, i.e., it is optimalized for managing the requirements of everyday situations. These requirements have gradually modified the human visual system in the course of evolution and also led to the forming of internal constraints (presuppositions)

Cognition 2006

Researchers from the fields of psychology, philosophy, neuroscience, linguistics, biology and computer science discussed on the current state of the research on cognition. The conference Kognice 2006 offered the platform for the interdisciplinary dialogue and for learning about the very different approaches and languages which are linked by their curiosity on the nature of the human mind

The research on visual space perception: Introduction

Visual space perception is thoroughly examined topic. The relevant questions attracted the natural philosophers since the antiquity. In the article, we introduce in short the main problems empirically studied, the methods used and some of the principal results. Also our own experimental research is dealt with in detail

Visual space perception: Introduction

The topic visual space perception is widely investigated for a long time. During the history, it was of the principle interest for philosophy, visual arts, geometry, optics, physiology and other disciplines. Also, in the times beginning of psychology as a science, the research was often concerned with the questions related to depth perception. In this paper, we introduce the principle questions studied in the field together with the experimental methods used and characteristic results. Finally, we present our own research focused on trade-off between particular spatial descriptors and on selected aspects of the relationship between visual and physical space

Why are Psychological Theories Intelligible to all People

The authors try to prove in their paper that a great part of psychological principles is evident to the laymen public. The majority of people is able to infer it easy on the basis of their life experience. The questionnaire was presented to the heteroogeneous sample of 15 laymen. The items were formulated by the means of common, non-expert language with possibility of choice of the right answer.It was proved that the majority of them was able to identify the right answer without problems. The authors draw the conclusion from that fact that the basis of scientific psychology is made by common sense

The distorsion of a perceived structure in the direction of an observer`s line of sight

Human perception of 3-D structure is neither accurate, nor reliable since the image is largely determined by the different object`s distances from an observer and object`s orientations with respect to an observer. Perception of 3-D structure is severely distorted especially when the observed object align with the observer`s sight. We studied the accuracy and reliability of perception in these conditions for moving geometrical objects. Subjects were to compare the relative depth of two simultaneously exposed half-ellipsoids. These objects were mutually identical with exception of their elongation directly to the depth. The difference in their elongation varied from 5% to 20% of the second object`s depth. One of objects was oriented in the direction of observer`s sight, the second of objects in orientation 0°, 12°, or 24°. The results clearly demonstrate the misperception of third dimension and reveal the consistent bias to overestimate the depth of slanted one of two half-ellipsoids across all conditions

Less is sometime more also in the experimental research of visual space perception

In the methodological study, the authors propose the classification of the tasks used in the experimental research of visual space perception. Each task has its advantages and limitations. It concerns with the requirements posed on the observers, the level of quantification of the data, the ecological validity of findings, and the danger of the infiltration of judgments by the artifacts. The authors propose to distinguish the metric (exact, euclidean) from the nonmetric (up to ordinal) tasks. All of the differences will be demonstrated on the specific experimental designs

Vision after 53 Years of Blindness

Several studies have shown that visual recovery after blindness that occurs early in life is never complete. The current study investigated whether an extremely long period of blindness might also cause a permanent impairment of visual performance, even in a case of adult-onset blindness. We examined KP, a 71-year-old man who underwent a successful sight-restoring operation after 53 years of blindness. A set of psychophysical tests designed to assess KP's face perception, object recognition, and visual space perception abilities were conducted six months and eight months after the surgery. The results demonstrate that regardless of a lengthy period of normal vision and rich pre-accident perceptual experience, KP did not fully integrate this experience, and his visual performance remained greatly compromised. This was particularly evident when the tasks targeted finer levels of perceptual processing. In addition to the decreased robustness of his memory representations, which was hypothesized as the main factor determining visual impairment, other factors that may have affected KP's performance were considered, including compromised visual functions, problems with perceptual organization, deficits in the simultaneous processing of visual information, and reduced cognitive abilities