Biomedical subjects

Malika Auvray

Publications and source records attributed to Malika Auvray.

4 recordsLinked to original sources

PubMed2006

Crossmodal change blindness between vision and touch.

Change blindness is the name given to people's inability to detect changes introduced between two consecutively-presented scenes when they are separated by a distractor that masks the transients that are typically associated with change. Change blindness has been reported within vision, audition, and touch, but has never before been investigated when successive patterns are presented to different sensory modalities. In the study reported here, we investigated change detection performance when the two to-be-compared stimulus patterns were presented in the same sensory modality (i.e., both visual or both tactile) and when one stimulus pattern was tactile while the other was presented visually or vice versa. The two to-be-compared patterns were presented consecutively, separated by an empty interval, or else separated by a masked interval. In the latter case, the masked interval could either be tactile or visual. The first experiment investigated visual-tactile and tactile-visual change detection performance. The results showed that in the absence of masking, participants detected changes in position accurately, despite the fact that the two to-be-compared displays were presented in different sensory modalities. Furthermore, when a mask was presented between the two to-be-compared displays, crossmodal change blindness was elicited no matter whether the mask was visual or tactile. The results of two further experiments showed that performance was better overall in the unimodal (visual or tactile) conditions than in the crossmodal conditions. These results suggest that certain of the processes underlying change blindness are multisensory in nature. We discuss these findings in relation to recent claims regarding the crossmodal nature of spatial attention.

Adult↗

PubMed2006

Effectiveness of a guideline for venous thromboembolism prophylaxis in elderly post-acute care patients: a multicenter study with systematic ultrasonographic examination.

BACKGROUND: Thromboprophylaxis in elderly patients, including post-acute care patients, is at variance with scientific evidence. The purpose of this study was to determine whether a multifaceted intervention was followed by a decrease in deep venous thrombosis (DVT). METHODS: A prospective preintervention-postintervention study was conducted in 1373 patients (preintervention phase, n = 709; postintervention phase, n = 664), aged 65 years or older, enrolled in 33 hospital-based post-acute care facilities in France. An evidence-based guideline addressing pharmacologic and mechanical prophylaxis was implemented through a multifaceted intervention. The main outcome measure was any DVT diagnosed at routine comprehensive ultrasonography performed by registered angiologists. RESULTS: A DVT was found in 91 patients (12.8%) in the preintervention phase and in 52 patients (7.8%) in the postintervention phase (P = .002). The decrease in DVT involved the calf (7.1% vs 3.6%; P = .005) and the proximal venous segments (5.8% vs 4.2%; P = .18) and remained significant after adjusting for risk factors (adjusted odds ratio of any DVT, 0.58; 95% confidence interval, 0.39-0.86). Pharmacologic prophylaxis with either low-molecular-weight heparin at the high-risk dose, unfractionated heparin, and vitamin K antagonist was similar in the 2 study groups, whereas patients in the postintervention group were more likely to use graduated compression stockings (27.4% vs 34.6%; P = .004) and less likely to receive low-molecular-weight heparin at the low-risk dose (24.7% vs 18.5%; P = .006), which was not recommended by our guideline. CONCLUSIONS: A multifaceted intervention addressing venous thromboembolism prophylaxis in post-acute care patients can be followed by a significant decrease in the rate of any DVT in elderly patients. More active interventions are needed to enforce compliance with evidence-based guidelines.

Aged↗

PubMed2006

When visual transients impair tactile change detection: a novel case of crossmodal change blindness?

The inability of people to detect changes between consecutively presented visual displays, when separated by a blank screen or distractor, is known as "change blindness". This phenomenon has recently been reported to occur within the auditory and tactile modalities as well. To date, however, only distractors presented within the same sensory modality as the change have been demonstrated to produce change blindness. In the present experiment, we studied whether tactile change blindness might also be elicited by the presentation of a visual mask. Participants made same versus different judgments regarding two successively presented displays composed of two to three vibrotactile stimuli. While change detection performance was near-perfect when the two displays were presented one directly after the other, participants failed to detect many of the changes between the tactile displays when they were separated by an empty temporal interval. Critically, performance deteriorated still further when the presentation of a local (i.e., a mudsplash) or global visual transient coincided with the onset of the second tactile pattern. Analysis of the results using signal detection theory revealed that this crossmodal effect reflected a genuine perceptual impairment.

Adult↗

PubMed2005

There is something out there: distal attribution in sensory substitution, twenty years later.

Sensory substitution constitutes an interesting domain of study to consider the philosopher's classical question of distal attribution: how we can distinguish between a sensation and the perception of an object that causes this sensation. We tested the hypothesis that distal attribution consists of three distinct components: an object, a perceptual space, and a coupling between subjects' movements and stimulation. We equipped sixty participants with a visual-to-auditory substitution device, without any information about it. The device converts the video stream produced by a head-mounted camera into a sound stream. We investigated several experimental conditions: the existence or not of a correlation between movements and resulting stimulation, the direct or indirect manipulation of an object, and the presence of a background environment. Participants were asked to describe their impressions by rating their experiences in terms of seven possible "scenarios". These scenarios were carefully chosen to distinguish the degree to which the participants attributed their sensations to a distal cause. Participants rated the scenarios both before and after they were given the possibility to interrupt the stimulation with an obstacle. We were interested in several questions. Did participants extract laws of co-variation between their movements and resulting stimulation? Did they deduce the existence of a perceptual space originating from this coupling? Did they individuate objects that caused the sensations? Whatever the experimental conditions, participants were able to establish that there was a link between their movements and the resulting auditory stimulation. Detection of the existence of a coupling was more frequent than the inferences of distal space and object.

Auditory Perception↗