Search results for "Space perception"
showing 10 items of 136 documents
Surface Lightness Influences Perceived Room Height
2010
Surprisingly little scientific research has been conducted on the effects of colour and lightness on the perception of spaciousness. Practitioners and architects typically suggest that a room's ceiling appears higher when it is painted lighter than the walls, while darker ceilings appear lower. Employing a virtual reality setting, we studied the effects of the lightness of different room surfaces on perceived height in two psychophysical experiments. Observers judged the height of rooms varying in physical height as well as in the lightness of ceiling, floor, and walls. Experiment 1 showed the expected increase of perceived height with increases in ceiling lightness. Unexpectedly, the perce…
Spatial Inferences in Narrative Comprehension: the Role of Verbal and Spatial Working Memory
2016
During the comprehension of narrative texts, readers keep a mental representation of the location of protagonists and objects; a breach in spatial coherence is detected by longer online reading times (consistency effect). We addressed whether these spatial inferences involve verbal or spatial working memory in two experiments, combining the consistency paradigm with selective verbal and spatial working memory concurrent tasks. The first experiment found longer reading times with a concurrent spatial task under imagery instructions (t33 = 2.87, p =.021). The second experiment, under comprehension reading instructions, found effects of verbal interference on reading times and accuracy. With a…
Accommodative stimulus-response curves to low-pass filtered natural images
2018
To assess how the monocular steady-state accommodative stimulus-response curve is modified when viewing low-pass filtered natural images. Eighteen adult subjects participated in the study. The accommodative stimulus-response curve was objectively assessed by means of a Hartmann-Shack wavefront sensor. Measurements were taken at different accommodative demands. Target images were low-pass filtered versions of a natural image that were obtained applying different digital spatial filters that limited the spatial frequency content of the natural image. Cutoff spatial frequencies were set at 30, 21, and 15 cycles per degree (cy/deg). Mean data obtained for each target were fitted to linear model…
Integration of cognitive allocentric information in visuospatial short-term memory through the hippocampus
2005
Visuospatial short-term memory relies on a widely distributed neocortical network: some areas support the encoding process of the visually acquired spatial information, whereas other ares are more involved in the active maintenance of the encoded information. Recently, in a pointing to remembered targets task, it has been shown in healthy subjects that, for memory delays of 5 s, spatial errors are affected also by cognitive allocentric information, i.e., covert spatial information derived from a pure mental representation. We tested the effect of a lesion of the hippocampus on the accuracy of pointing movements toward remembered targets, with memory delays falling in the 0.5-30 s range. The…
Visual inference of arm movement is constrained by motor representations
2015
International audience; Several studies support the idea that motion inference is strongly motor dependent. In the present study, we address the role of biomechanical constraints in motion prediction and how this implicit knowledge can interfere in a spatial prediction task. Right-handed (RHS) and left-handed subjects (LHS) had to estimate the final position of a horizontal arm movement in which the final part of the trajectory was hidden. Our study highlighted a direction effect: end point prediction accuracy was better to infer the final position of horizontal motion directed toward the median line of human body. This finding suggests that the spatial prediction of end point is mapped ont…
Human walking along a curved path. II. Gait features and EMG patterns
2003
We recorded basic gait features and associated patterns of leg muscle activity, occurring during continuous body progression when humans walked along a curved trajectory, in order to gain insight into the nervous mechanisms underlying the control of the asymmetric movements of the two legs. The same rhythm was propagated to both legs, in spite of inner and outer strides diverging in length (P < 0.001). There was a phase lag in limb displacement between the inner and outer leg of 7% of the total cycle duration (P = 0.0001). Swing velocity was greater for outer than inner foot (P < 0.001). The duration of the stance phase diminished and increased in the outer and inner leg (P < 0.01), respect…
Visuospatial deficits in schizophrenia: central executive and memory subsystems impairments
2002
Object and spatial visual working memory are impaired in schizophrenic patients. It is not clear if the impairments reside in each memory subsystem alone or also in the central executive component that coordinates these processes. In order to elucidate which memory component is impaired, we developed a paradigm with single spatial and object working memory tasks and dual ones with two different delays (5 and 30 s). Fifteen schizophrenic patients and 14 control subjects performed these tests. Schizophrenic patients had a poorer performance compared to normal controls in all tasks and in all time delays. Both schizophrenics and controls performed significantly worse in the object task than in…
Differentiating the differential rotation effect.
2011
As an observer views a picture from different viewing angles, objects in the picture appear to maintain their orientation relative to the observer. For instance, the eyes of a portrait appear to follow the observer as he or she views the image from different angles. We have explored this rotation effect, often called the Mona Lisa effect. We report three experiments that used portrait photographs to test variations of the Mona Lisa effect. The first experiment introduced picture displacements relative to the observer in directions beyond the horizontal plane. The Mona Lisa effect remained robust for vertical and/or diagonal observer displacements. The experiment also included conditions in …
Neck Muscle Vibration and Spatial Orientation During Stepping in Place in Humans
2002
Unilateral long-lasting vibration was applied to the sternomastoid muscle to assess the influence of asymmetric neck proprioceptive input on body orientation during stepping-in-place. Blindfolded subjects performed 3 sequences of 3 trials, each lasting 60 s: control, vibration applied during stepping (VDS), and vibration applied before stepping (VBS). VDS caused clear-cut whole body rotation toward the side opposite to vibration. The body rotated around a vertical axis placed at about arm's length from the body. The rotation did not begin immediately on switching on the vibrator. The delay varied from subject to subject from a few seconds to about 10 s. Once initiated, the angular velocity…
Perceptual-Cognitive Skills and Performance in Orienteering
2008
The goal was analysis of the perceptual-cognitive skills associated with sport performance in orienteering in a sample of 22 elite and 17 nonelite runners. Variables considered were memory, basic orienteering techniques, map reading, symbol knowledge, map-terrain-map identification, and spatial organisation. A computerised questionnaire was developed to measure the variables. The reliability of the test (agreement between experts) was 90%. Findings suggested that competence in performing basic orienteering techniques efficiently was a key variable differentiating between the elite and the nonelite athletes. The results are discussed in comparison with previous studies.