Tactile Acuity Charts: A Reliable Measure of Spatial Acuity

Abstract

For assessing tactile spatial resolution it has recently been recommended to use tactile acuity charts which follow the design principles of the Snellen letter charts for visual acuity and involve active touch. However, it is currently unknown whether acuity thresholds obtained with this newly developed psychophysical procedure are in accordance with established measures of tactile acuity that involve passive contact with fixed duration and control of contact force. Here we directly compared tactile acuity thresholds obtained with the acuity charts to traditional two-point and grating orientation thresholds in a group of young healthy adults. For this purpose, two types of charts, using either Braille-like dot patterns or embossed Landolt rings with different orientations, were adapted from previous studies. Measurements with the two types of charts were equivalent, but generally more reliable with the dot pattern chart. A comparison with the two-point and grating orientation task data showed that the test-retest reliability of the acuity chart measurements after one week was superior to that of the passive methods. Individual thresholds obtained with the acuity charts agreed reasonably with the grating orientation threshold, but less so with the two-point threshold that yielded relatively distinct acuity estimates compared to the other methods. This potentially considerable amount of mismatch between different measures of tactile acuity suggests that tactile spatial resolution is a complex entity that should ideally be measured with different methods in parallel. The simple test procedure and high reliability of the acuity charts makes them a promising complement and alternative to the traditional two-point and grating orientation thresholds.

Not only age but also tactile perception influences the preference for cosmetic creams applied to the forearm

“…The Landolt ring test is a highly reliable test of higher‐order tactile perceptual abilities and relies on more cognitive resources in comparison with the other two tactile tests . The relation between higher‐order tactile perception and the evaluation of cosmetic products seem to be highly complex mechanisms that require not only the active and attentive ability to focus on the percept, but also the ability to sense a product intensely.…”

“…It might be assumed that the more basic tests of tactile sensitivity and texture discrimination are more closely associated with age than the Landolt ring test and therefore do not have additional explanatory power. The latter test, however, much more depends on cognitive factors that reveal a huge variability of lifespan developmental trajectories.…”

“…The Landolt ring test was applied in order to identify the individual spatial tactile discrimination threshold. One Landolt ring chart included eleven rows with 4–8 rings in decreasing sizes in an acuity chart fabricated by polymer material.…”

“…The orientation of the gap had to be detected by moving the fingertip over the respective ring. All characters had an elevation of 0.4 mm . Note that the size of the C changes in proportion to the size of the gap (ratio 5:1) in each row.…”

Ability to recognize and identify the location of vibration stimulation on the fingers

“…And it was also suggested that the two point threshold may not represent effective measures space vision [9,11]. However, the most prominent alternative to the classical two-point threshold discussed in the literature is the grating orientation threshold (GOT) [12].…”