Search results for " PSI"
showing 10 items of 2972 documents
The hippocampus is required for short-term topographical memory in humans.
2007
The hippocampus plays a crucial role within the neural systems for long-term memory, but little if any role in the short-term retention of some types of stimuli. Nonetheless, the hippocampus may be specialized for allocentric topographical processing, which impacts on short-term memory or even perception. To investigate this we developed performance-matched tests of perception (match-to-sample) and short-term memory (2 s delayed-match-to-sample) for the topography and for the nonspatial aspects of visual scenes. Four patients with focal hippocampal damage and one with more extensive damage, including right parahippocampal gyrus, were tested. All five patients showed impaired topographical m…
Repetitive transcranial magnetic stimulation over the left parietal cortex facilitates visual search for a letter among its mirror images
2015
Interference by task irrelevant information is seen in visual search paradigms using letters. Thus, it is harder to find the letter 'N' among its mirror reversals 'Icyrillic' than vice versa. This observation, termed the reversed letter effect, involves both a linguistic association and an interference of task irrelevant information - the shape of 'N' or 'Icyrillic' is irrelevant, the search requires merely distinguishing the tilts of oblique bars. We adapted the repetitive transcranial magnetic stimulation (rTMS) methods that we previously used, and conducted three rTMS experiments using healthy subjects. The first experiment investigated the effects of rTMS on the left and right posterior…
Impairments in top down attentional processes in right parietal patients: Paradoxical functional facilitation in visual search
2014
AbstractIt is well known that the right posterior parietal cortex (PPC) is involved in attentional processes, including binding features. It remains unclear whether PPC is implicated in top-down and/or bottom-up components of attention. We aim to clarify this by comparing performance of seven PPC patients and healthy controls (HC) in a visual search task involving a conflict between top-down and bottom-up processes. This task requires essentially a bottom-up feature search. However, top-down attention triggers feature binding for object recognition, designed to be irrelevant but interfering to the task. This results in top-down interference, prolonging the search reaction time. This interfe…
Anatomical correlates of visual and tactile extinction in humans: a clinical CT scan study.
1994
The anatomical correlates of tactile and visual extinction with double simultaneous stimulation were investigated in a series of 159 patients with right brain damage caused by stroke. Forty six patients showed extinction (22 tactile, 14 visual, 10 tactile and visual). Over 50% of the patients with extinction had deep lesions, which were found in about 25% of the patients with visuospatial neglect not associated with extinction. In the patients with extinction and cortico-subcortical damage the paraventricular occipital white matter and the dorsolateral frontal cortex were most often involved. By contrast, when neglect was also present, the lesions clustered in the inferior parietal lobule. …
Unconscious processing of Arabic numerals in unilateral neglect
2005
This study explores the processing of Arabic numerals in three patients with dense left unilateral neglect. Three tasks have been used: a test of visual awareness (is the stimulus on the left, on the right or on both sides?), a number comparison task (is the number larger or smaller than 5?), a number parity judgment task (is the number odd or even?). The test of visual awareness indicated that all three patients were completely unaware of the stimuli presented in the left hemifield. Despite this, the number comparison and number parity judgment tasks clearly indicated that Arabic numerals were unconsciously processed at semantic level (i.e. quantity). These results show that patients with …
Recognition memory for single items and for associations in amnesic patients
2004
Recognition memory performance reflects two distinct processes or types of memory referred to as recollection and familiarity. According to theoretical claims about the two types of memory, single item and associative recognition tasks can be used as an experimental method to distinguish recollection and familiarity processes. Associative recognition decisions can be used as an index of recollection while memory for single items is mostly based on familiarity judgement. We employed this procedure to examine a possible dissociation in the memory performance of amnesic patients between spared single item and impaired associative recognition. Twelve amnesic patients, six with damage confined t…
Kinematic features of movement tunes perception and action coupling
2005
How do we extrapolate the final position of hand trajectory that suddenly vanishes behind a wall? Studies showing maintenance of cortical activity after objects in motion disappear suggest that internal model of action may be recalled to reconstruct the missing part of the trajectory. Although supported by neurophysiological and brain imaging studies, behavioural evidence for this hypothesis is sparse. Further, in humans, it is unknown if the recall of internal model of action at motion observation can be tuned with kinematic features of movement. Here, we propose a novel experiment to address this question. Each stimulus consisted of a dot moving either upwards or downwards, and correspond…
Exploring the relationship between semantics and space
2009
The asymmetric distribution of human spatial attention has been repeatedly documented in both patients and healthy controls. Biases in the distribution of attention and/or in the mental representation of space may also affect some aspects of language processing. We investigated whether biases in attention and/or mental representation of space affect semantic representations. In particular, we investigated whether semantic judgments could be modulated by the location in space where the semantic information was presented and the role of the left and right parietal cortices in this task. Healthy subjects were presented with three pictures arranged horizontally (one middle and two outer picture…
Changes in physical activity among coronary and hypertensive patients: A longitudinal study using the Health Action Process Approach
2017
Objectives: Physical activity (PA) is a key factor in cardiovascular disease prevention. Through the Health Action Process Approach (HAPA), the present study investigated the process of change in PA in coronary patients (CPs) and hypertensive patients (HPs). Design: Longitudinal survey study with two follow-up assessments at 6 and 12 months on 188 CPs and 169 HPs. Main outcome measures: Intensity and frequency of PA. Results: A multi-sample analysis indicated the equivalence of almost all the HAPA social cognitive patterns for both patient populations. A latent growth curve model showed strong interrelations among intercepts and slopes of PA, planning and maintenance self-efficacy, but chan…
Factorial Structure of Web-Credibility in a population of Italian Internet Users. A pilot study
2009
Recent studies by Fogg and his colleagues have defined a new psychological construct called Web credibility. It describes the principal dimensions which lead people to believe (or not) online information. In this framework, the factorial structure of Web credibility was explored in a sample of 152 Italian students of psychology who were Internet users, using a questionnaire. A consistent four-factorial structure emphasized crucial aspects of Web credibility, namely, Inaccuracy, Efficiency, Social Validation, and Commercial Features. Such results seem in line with Fogg's theoretical model; however, further research is required to identify dimensions of this construct.