Isabelle Legault

Healthy Older Observers Show Equivalent Perceptual-Cognitive Training Benefits to Young Adults for Multiple Object Tracking

The capacity to process complex dynamic scenes is of critical importance in real life. For instance, traveling through a crowd while avoiding collisions and maintaining orientation and good motor control requires fluent and continuous perceptual-cognitive processing. It is well documented that effects of healthy aging can influence perceptual-cognitive processes (Faubert, 2002) and that the efficiency of such processes can improve with training even for older adults (Richards et al., 2006). Here we assess the capacity of older participants to improve their tracking speed thresholds in a dynamic, virtual reality environment. Results show that this capacity is significantly affected by healthy aging but that perceptual-cognitive training can significantly reduce age-related effects in older individuals, who show an identical learning function to younger healthy adults. Data support the notion that learning in healthy older persons is maintained for processing complex dynamic scenes.

Perceptual-cognitive training improves biological motion perception: evidence for transferability of training in healthy aging

In our everyday life, processing complex dynamic scenes such as crowds and traffic is of critical importance. Further, it is well documented that there is an age-related decline in complex perceptual-cognitive processing, which can be reversed with training. It has been suggested that a specific dynamic scene perceptual-cognitive training procedure [the three-dimensional multiple object tracking speed task (3D-MOT)] helps observers manage socially relevant stimuli such as human body movements as seen in crowds or during sports activities. Here, we test this assertion by assessing whether training older observers on 3D-MOT can improve biological motion (BM) perception. Research has shown that healthy older adults require more distance in virtual space between themselves and a point-light walker to integrate BM information than younger adults. Their performances decreased markedly at a distance as far away as 4 m (critical for collision avoidance), whereas performance in young adults remained constant up to 1 m. We trained observers between 64 and 73 years of age on the 3D-MOT speed task and looked at BM perception at 4 and 16 m distances in virtual space. We also had a control group trained on a visual task and a third group without training. The perceptual-cognitive training eliminated the difference in BM perception between 4 and 16 m after only a few weeks, whereas the two control groups showed no transfer. This demonstrates that 3D-MOT training could be a good generic process for helping certain observers deal with socially relevant dynamic scenes.

The effects of blurred vision on auditory-visual speech perception in younger and older adults

Abstract Speech understanding is improved when the observer can both see and hear the talker. This study compared the effects of reduced visual acuity on auditory-visual (AV) speech-recognition in noise among younger and older adults. Two groups of participants performed a closed-set sentence-recognition task in one auditory-alone (A-alone) condition and under three AV conditions: normal visual acuity (6/6), and with blurred vision to simulate a 6/30 and 6/60 visual impairment. The results showed that (1) the addition of visual speech cues improved speech-perception relative to the A-alone condition, (2) under the AV conditions, performance declined as the amount of blurring increased, (3) even under the AV condition that simulated a visual acuity of 6/60, the speech recognition scores were significantly higher than those obtained under the A-alone condition, and (4) generally, younger adults obtained higher scores than older adults under all conditions. Our results demonstrate the benefits of visual cues to enhance speech understanding even when visual acuity is not optimal. Sumario La comprensión del lenguaje mejora cuando el observador puede tanto ver como oír a su interlocutor. Este estudio compara los efectos de una agudeza visual reducida, en el reconocimiento auditivo-visual (AV) del lenguaje con ruido, entre adultos jóvenes y mayores. Dos grupos de participantes realizaron una tarea de reconocimiento de oraciones en contexto cerrado en una condición solo auditiva (Solo-A) y en tres condiciones AV: con agudeza visual normal (6/6) y con visión borrosa simulando impedimentos visuales de 6/30 y 6/60. Los resultados mostraron: (1) la adición de claves visuales de lenguaje mejora la percepción del mismo en relación con la condición de Solo-A; (2) en las condiciones AV, el desempeño declinó conforme aumentó el grado de visión borrosa; (3) incluso en la condición AV que simulaba una agudeza visual de 6/60, las puntuaciones en el reconocimiento del lenguaje fueron significativamente superiores que las obtenidas en la condición de Solo-A y (4) generalmente, los adultos jóvenes obtuvieron puntuaciones más altas que los adultos mayores, en todas las condiciones. Nuestros resultados demuestran los beneficios de las claves visuales para aumentar la comprensión del lenguaje, incluso cuando la agudeza visual no es óptima.

Cholinergic Potentiation Improves Perceptual-Cognitive Training of Healthy Young Adults in Three Dimensional Multiple Object Tracking

A large body of literature supports cognitive enhancement as an effect of cholinergic potentiation. However, it remains elusive whether pharmacological manipulations of cholinergic neurotransmission enhance complex visual processing in healthy individuals. To test this hypothesis, we randomly administered either the cholinergic transmission enhancer donepezil (DPZ; 5 mg P.O.) or placebo (lactose) to young adults (n = 17) 3 h before each session of the three-dimensional (3D) multiple object tracking (3D-MOT) task. This multi-focal attention task evaluates perceptual-cognitive learning over five sessions conducted 7 days apart. A significant amount of learning was observed in the DPZ group but not the placebo group in the fourth session. In the fifth session, this learning effect was observed in both groups. Furthermore, preliminary results for a subgroup of participants (n = 9) 4–14 months later suggested the cholinergic enhancement effect was long lasting. On the other hand, DPZ had no effect on basic visual processing as measured by a motion and orientation discrimination task performed as an independent one-time, pre-post drug study without placebo control (n = 10). The results support the construct that cholinergic enhancement facilitates the encoding of a highly demanding perceptual-cognitive task although there were no significant drug effects on the performance levels compared to placebo.

Normal Aging and the Perception of Curvature Shapes

Purpose. The present study assessed whether different curve geometries involve different perceptual processing levels and whether these perceptual requirements can interact with the normal aging process. Methods. Amplitude thresholds for three different curve types were assessed for young and older observers using 2AFC psychophysical methods. The stimuli were individually adjusted for visibility. The three stimulus types evaluated represented a bell shape, a quadratic, and a compressed arc function. Results. As predicted, the geometry influenced the perception of curvature where the compressed arc was most difficult to perceive followed by the quadratic and bell-shaped curves. Moreover, older observers showed relatively higher thresholds for the quadratic and compressed arc shapes, while they had similar thresholds to the younger observers for the bell-shaped function. Conclusions. In general, the data support the notion that aging affects the processing of curvature requiring the integration of oriented receptors. This is in accordance with studies that have found reduced orientation selectivity of cortical neurons in senescent animals. Our findings suggest that older observers would have more difficulties with form discrimination tasks where curvature is an inherent component of the image and also predict age-related differences in perceiving ophthalmic lens-induced distortions.

Does donepezil improve visual stimuli detection and perceptivo-cognitive performance of heathy young adults ?

Donepezil enhances the cholinergic synaptic transmission in the brain by inhibiting the enzyme that metabolizes acetylcholine in the synaptic cleft, thereby prolonging the action of this neurotransmitter. It has been demonstrated that chronic administration of donepezil increases perceptual learning. Our study examines the effect of acute administration of donepezil on first and second order visual stimuli detection on one hand and on perceptual-cognitive performance on the other hand. A double-blind, placebo controlled design was used to evaluate the effect of cholinergic enhancement - donepezil administration (5 mg, given per os) - on visual attention using two different attention tasks. 10 young healthy adults were enrolled in each group. The task was performed 3 hours after the donepezil (or placebo) intake to synchronize with the peak plasma concentration of the drug. We started by testing the first and second order visual detection for motion and direction using the Neurominder task (Habak & Faubert, 2000) before and after taking donepezil. Motion and direction identification thresholds for the first order and second order visual detection were identical before and after donepezil intake. The multifocal attention of the participant was tested by the multiple object tracking task (Legault and Faubert, 2012). During this perceptual-cognitive task, the observer is required to simultaneously track multiple moving items among distracters in a dynamic virtual reality environment. The task is repeated once a week during 5 weeks to test the effect of learning. The speed thresholds in the MOT task increased significantly in each session in the same range for both donepezil and control groups. Our results suggest that an acute 5mg dose of donepezil might not be sufficient to elicit perceptual-cognitive or visual detection performance improvement when given to healthy young subjects. Additional studies are needed to better define the involvement of acetylcholine enhancement on perceptual learning/attentional tasks. Meeting abstract presented at VSS 2015.