Gérard Olivier

Visual objects can potentiate a grasping neural simulation which interferes with manual response execution

Previous studies on visuomotor priming have provided insufficient information to determine whether the reach-to-grasp potentiation of a non-target object produces a specific effect during response execution. In order to answer this question, subjects were instructed to reach and grasp a response device with either a power or a precision grip, depending on whether the stimulus they saw was empty or full. Stimuli consisted of containers (graspable with either a power or a precision grip), with non-graspable stimuli added as a control condition (geometrical shapes). The image of the non-target object was removed during the execution phase. Results demonstrate slower execution responses related to motor incompatibility, though conversely, no faster responses with motor compatibility. Moreover, any visuomotor priming effect required that the container be displayed during response execution. These data suggest that during response execution, motor incompatibility produces a disruptive effect likely due to competition between two cerebral events: motor control of the actual response execution and visual object reach-to-grasp neural simulation.

Motor dimension of visual mental image transformation processes

This paper concerns the influence of perceptual motor skills on the transformation processes during mental visual imaging. We first administered a visual recognition task to subjects, during which they scanned and rotated visual mental images. Then, we measured motor skills in perceptual situations. The main result is that both mental scanning and mental rotation processes are quicker when they simulate a perceptual motor skill of the subject. Furthermore, mental rotation seems to be canceled when the hemisphere activated by perception has to control the behavioral response. These results suggest that visual mental images are transformed partly via motor processes.

Visuomotor priming of a manual reaching movement during a perceptual decision task

This paper deals with the mental simulation of manual movement that sometimes accompanies the visual perception of an object. Previous studies investigated how visual objects prime the grasping manual movement they afford. The principal purpose of the present experiment was to determine if such visuomotor priming also concerns the reaching manual movement that visual objects afford. During a perceptual decision task, 32 subjects were asked to grasp a proximal or distal switch, as fast and accurately as possible, depending on the color of a chess piece displayed on a computer screen. Results showed an effect on the reaction times of the interaction between the position of the chess piece on the chessboard and the manual response, suggesting that subjects mentally simulated a manual reaching movement toward the perceived chess piece.

Mental rotation and simulation of a reaching and grasping manual movement.

This paper deals with the kind of manual movement subjects mentally simulate when solving a left-right judgment task that requires rotating images of hands. 50 female students were asked to judge the laterality of drawings of rotated hands presented successively to the right and left visual hemifields by clicking on a mouse using either the right or left hand. Reaction times and accuracy of judgment were recorded. Analysis showed performances varied with the rotation angle at which the stimulus was presented, indicating that the subjects mentally simulated a rotation process. An interaction occurred between the visually presented hand and the responding hand, which suggests that the mental rotation process involved the simulation of a hand movement. Performance improved when the drawing of a hand was presented in the ‘palm-up’ position, and to the visual hemifield opposite with respect to the hand the subject moved mentally. The latter two findings suggest that the subjects performed a simulated reaching and grasping movement rather than a simulated positioning movement.

Motor transfer from map ocular exploration to locomotion during spatial navigation from memory

Spatial navigation from memory can rely on two different strategies: a mental simulation of a kinesthetic spatial navigation (egocentricroute strategy) or visual-spatial memory using a mental map (allocentric survey strategy). We hypothesized that a previously performed “oculomotor navigation” on a map could be used by the brain to perform a locomotor memory task. Participants were instructed to (1) learn a path on a map through a sequence of vertical and horizontal eyes movements and (2) walk on the slabs of a “magic carpet” to recall this path. The main results showed that the anisotropy of ocular movements (horizontal ones being more efficient than vertical ones) influenced performances of participants when they change direction on the central slab of the magic carpet. These data suggest that, to find their way through locomotor space, subjects mentally repeated their past ocular exploration of the map, and this visuo-motor memory was used as a template for the locomotor performance.

Generation of oculomotor images during tasks requiring visual recognition of polygons.

This paper concerns the contribution of mentally simulated ocular exploration to generation of a visual mental image. In Exp. 1, repeated exploration of the outlines of an irregular decagon allowed an incidental learning of the shape. Analyses showed subjects memorized their ocular movements rather than the polygon. In Exp. 2, exploration of a reversible figure such as a Necker cube varied in opposite directions. Then, both perspective possibilities are presented. The perspective the subjects recognized depended on the way they explored the ambiguous figure. In both experiments, during recognition the subjects recalled a visual mental image of the polygon they compared with the different polygons proposed for recognition. To interpret the data, hypotheses concerning common processes underlying both motor intention of ocular movements and generation of a visual image are suggested.

Preparation of forefinger’s sequence on keyboard orients ocular fixations on computer screen

This study examined the links between attention, hand movements and eye movements when performed in different spatial areas. Participants performed a visual search task on a computer screen while preparing to press two keyboard keys sequentially with their index. Results showed that the planning of the manual sequence influenced the latency of the first saccade and the placement of the first fixation. In particular, even if the first fixation placement was influenced by the combination of both components of the prepared manual sequence in some trials, it was affected principally by the first component of the prepared manual sequence. Moreover, the probability that the first fixation placement did reflect a combination of both components of the manual sequence was correlated with the speed of the second component. This finding suggests that the preparation of the second component of the sequence influence simultaneous oculomotor behavior when motor control of the manual sequence relied on proactive motor planning. These results are discussed taking into account the current debate on the eye/hand coordination research.

Ocular pursuit and visual memory of moving shapes

This paper deals with visual memory of moving shapes. During a visual recognition task, shapes moved on a computer screen, at a constant speed, and in a direction that was either similar, orthogonal or opposite to the direction of motion during learning. Results showed that correct response rate varies according to oculomotor factors: (1) the motor skill of ocular pursuit during learning and (2) the compatibility between motor control of ocular pursuits during learning and recognition. These data suggest that recognition of a moving shape is linked to recognition of ocular pursuits that subjects had previously repeated during shape learning. Possible neural substrates underlying this sensorimotor integration are discussed. More generally, these data shed light on the role of eye movements in visual memory organization.

Stimulus-Response Compatibility Effect in the Near-Far Dimension: A Developmental Study

The present study investigates the developmental aspect of stimulus-response compatibility (SRC) effect in 8–11-years-old children. The task consisted in manually responding to the color of a pawn presented on a chessboard at different distances. Manual responses were provided by reaching a proximal or distal location depending on the color of the stimulus. We found that reaction time was affected by the conflict generated by the response suggested by the location of the stimulus and the response required according to its color. This was not the case for movement time despite we found a higher rate of long duration movements in the incongruent than in the congruent spatial condition. The SRC effect was, however, observed in children older than 10 years old. These findings provide additional evidence for a reorganization of the perceptual system during the period of 8–10 years, integrating progressively multimodal information and preparing more efficiently the body to act in the environment.

Concurrent right–left and amplitude spatial congruency effects in a visual discrimination task

ABSTRACT During a perceptual task, the presentation of a visual stimulus is known to automatically activate a spatially congruent manual response, which influences the speed of the motor response provided depending on the non-spatial stimulus feature (e.g., colour). Such effect was found to depend on the congruency between either the (1) right–left stimulus location and lateralized manual response (Simon effect), or (2) near–far stimulus location and manual response amplitude (Amplitude Congruency effect). In the present study, we conjointly manipulated Simon and Amplitude Congruency effects in a stimulus colour discrimination task. It was found that stimulus location potentiated concurrent but independent Simon and Amplitude Congruency effects: the more the to-be-executed response was congruent with the response activated by these effects, the faster was its execution. Moreover, our results suggest that the magnitude of Amplitude Congruency effect on response latency and execution time reflects the temporal characteristics of the motor response planning.