An n-back task using vibrotactile stimulation with comparison to an auditory analogue

Tactile Working Memory Capacity of Users Who Are Blind in an Electronic Travel Aid Application with a Vibration Belt

Electronic travel aids (ETAs) can increase the safety and comfort of pedestrians who have a visual impairment by displaying obstacles through a vibrotactile navigation belt. Building a complete picture of relevant obstacles and finding a safe route requires ETA users to integrate vibrotactile cues over time and space in their tactile working memory. Previous research suggests that the sense of touch exhibits a working memory that has characteristics similar to vision and audition. However, the capacity of the tactile working memory and the effects of secondary tasks are still under-researched. We investigated tactile working memory capacity of 14 adolescent participants who are blind in an immediate, whole report recall test. Participants received trials consisting of one to five vibration patterns presented sequentially at different locations on their torso representing obstacles with a direction (vibration location) and distance (vibration pattern). Recall performance was assessed under four conditions: baseline and with distracting background sounds and/or while walking with the long cane. Both walking and ignoring distracting sounds are relevant for everyday use of an ETA and were expected to decrease memory performance. We calculated the 75% correct scores for two memory performance measures: the number of items in a trial (numerosity), and item location and pattern correct. In the baseline condition, the scores were close to ceiling (i.e., 5 items). However, in the presence of distracting sounds and while walking, the scores were reduced to 3.2 items for numerosity and 1.6 items for location and identity correct. We recommend using 2 items as the maximum tactile working memory load in an applied setting unless users are trained and/or can adopt their strategy without unacceptable costs, such as reducing their walking speed.

Tactile Display Design for Flight Envelope Protection and Situational Awareness

Spatial disorientation and visual channel saturation are defined as critical situations encountered by military pilots. Such subjects are interesting research areas likely to create innovative systems able to surmount obstacles of this kind. The integration of new stimulation techniques (sensory substitute, adjunct for visual and audio feedback) may be considered to make the visual channel better. This contribution may help in integrating tactile stimulation to improve or substitute the visual channel. It may also help to better interpret the spatial disorientation awareness signals and the vestibulo-ocular response limitations. The innovation of the proposed approach translates in: (i) the development of the PI-Inverse dynamics controller to provide a time delay reduction of the low cost tactile actuator, and thus, high-performance tactile system; (ii) an approach based on fuzzy logic controller (FLC) is being used in order to translate the turn rate angle, the flight path climb angle and the warning messages into tactile signal features instead of a conventional approach based on direct coding of the pitch and bank angles; and (iii) the consideration of the flight envelope. The fuzzy set translation of flight parameters into tactile signals is also a pragmatic and useful way to design the system.

Novel n-back spatial working memory task using eye movement response

We created a novel eye movement version of the n-back task to measure spatial working memory (WM). Rather than one continuous trial, discrete trials were presented in order to develop a simpler WM task. In Experiment 1, we varied the visibility of the final stimulus to maximize the difference in performance between 0-back and 1-back tasks (WM effect). In Experiment 2, we administered the optimized task to children. In Experiment 3, we further simplified the task. Both adults and children easily completed our task, displaying significant WM effects. Further, similar WM effects were obtained in our original and simplified n-back spatial WM tasks, demonstrating flexibility. Because WM deficits are often an early feature of disease and a marker of disease progression, our saccadic measure of spatial WM may be particularly useful in hard-to-test populations, such as patients and children, and may have application in brain-imaging studies that require discrete trials.

A cognitive training intervention improves modality-specific attention in a randomized controlled trial of healthy older adults

Age-related deficits in cognitive and sensory function can result in increased distraction from background sensory stimuli. This randomized controlled trial investigated the effects of a cognitive training intervention aimed at helping healthy older adults suppress irrelevant auditory and visual stimuli. Sixty-six participants received 8 weeks of either the modality-specific attention training program or an educational lecture control program. Participants who completed the intervention program had larger improvements in modality-specific selective attention following training than controls. These improvements also correlated with reductions in bimodal integration during selective attention. Further, the intervention group showed larger improvements than the control group in non-trained domains such as processing speed and dual-task completion, demonstrating the utility of modality-specific attention training for improving cognitive function in healthy older adults.