Haptic Working Memory Research Articles

The suppression of spontaneous face touch and resulting consequences on memory performance of high and low self-touching individuals

Spontaneous touching of one's own face (sFST) is an everyday behavior that occurs primarily in cognitively and emotionally demanding situations, regardless of a persons’ age or gender. Recently, sFST have sparked scientific interest since they are associated with self-inoculation and transmission of respiratory diseases. Several studies addressed the need to reduce sFST behaviors without discussing the underlying functions of this spontaneous behavior. In addition, the question of why this behavior occurs very frequently in some individuals (high self-touching individuals, HT) but less frequently in others (low self-touching individuals, LT) has not yet been addressed. For the first time, we distinguished between HT and LT and investigated the behavioral consequences of sFST suppression in these two groups. For this purpose, we examined performance outcomes of 49 participants depending on sFST behaviors during a haptic working memory task. In addition, we assessed personality traits of HT and LT using the Freiburg Personality Inventory (FPI-R). The results of our study reveal that suppressing sFST in HT is negatively related to memory performance outcomes. Moreover, HT show tendencies to differ from LT in certain personality traits. Our results highlight the relevance of distinguishing between HT and LT in future studies of sFST.

The Nature of Haptic Working Memory Capacity and Its Relation to Visual Working Memory

Abstract I conducted three experiments to investigate haptic working memory capacity using a haptic change detection task with 2D stimuli. I adopted a single-task paradigm comprising haptic single-feature (orientation or texture) and haptic multifeature (orientation and texture) conditions in Experiment 1 and a dual-task paradigm with a primary haptic orientation or texture change detection task and a concurrent secondary visual shape or colour change detection task in Experiments 2–3. I observed that in the single-task paradigm, haptic change detection capacity was higher for single features than it was for multiple features. In haptic working memory, unlike in visual working memory, features of two different dimensions within an object cannot be integrated. In the dual-task paradigm, interference was observed when the concurrent visual shape change detection task was combined with the haptic orientation change detection task although interference was not observed when the concurrent visual colour change detection task was combined with it. In addition, the concurrent visual shape or colour change detection task did not interfere with the capacity for haptic texture memory, which was higher than that for haptic orientation memory. These findings demonstrate that geometric properties perhaps retained a common storage system shared between haptic working memory and visual working memory; however, haptic texture might be retained in an independent stable storage system that is haptic-specific.

The Effects of Aging on Haptic Working Memory During Length Discrimination

Background: If human touch an object, even if they are blindfolded, they can reliably perceive its properties, such as temperature, material, length, height, texture and so on. In this study, we focused on investigating length perception, because length perception was an essential factor of object perception. Objective and Methods: 15 young and 15 old subjects participated in this experiment. They were blindfolded during experiment and actively grasped the displayed length with thumb and index finger and then perceived it. Two working memory-related experiments, varied delay times experiment and n-back experiment were performed separately, in order to investigate whether length discrimination abilities of young and old subjects degraded with aging. Results and Conclusion: With the increment of delay times, length discrimination threshold of both young and old subjects increased, delay times significantly affected length discrimination. No agerelated differences were found in varied delay times length discrimination experiment. However, we did confirm age-related differences in n-back length discrimination experiment. Keywords: Working memory, length discrimination, age, delay times, n-back, blindfolded.

Inferring the depth of 3-D objects from tactile spatial information

Four psychophysical experiments were conducted to examine the relation between tactile spatial information and the estimated depth of partially touched 3-D objects. Human participants touched unseen, tactile grating patterns with their hand while keeping the hand shape flat. Experiment 1, by means of a production task, showed that the estimated depth of the concave part below the touched grating was well correlated with the separation between the elements of the grating, but not with the overall size of the grating, nor with the local structure of the touched parts. Experiments 2 and 3, by means of a haptic working memory task, showed that the remembered depth of a target surface was biased toward the estimated bottom position of a tactile grating distractor. Experiment 4, by means of a discrimination task, revealed that tactile grating patterns influenced speeded judgments about visual 3-D shapes. These results suggest that the haptic system uses heuristics based on spatial information to infer the depth of an untouched part of a 3-D object.

Persistent Neuronal Firing in Primary Somatosensory Cortex in the Absence of Working Memory of Trial-specific Features of the Sample Stimuli in a Haptic Working Memory Task

Previous studies suggested that primary somatosensory (SI) neurons in well-trained monkeys participated in the haptic-haptic unimodal delayed matching-to-sample (DMS) task. In this study, 585 SI neurons were recorded in monkeys performing a task that was identical to that in the previous studies but without requiring discrimination and active memorization of specific features of a tactile or visual memorandum. A substantial number of those cells significantly changed their firing rate in the delay compared with the baseline, and some of them showed differential delay activity. These firing changes are similar to those recorded from monkeys engaged in active (working) memory. We conclude that the delay activity is not necessarily only observed as was generally thought in the situation of active memorization of different features between memoranda after those features have been actively discriminated. The delay activity observed in this study appears to be an intrinsic property of SI neurons and suggests that there exists a neural network in SI (the primary sensory cortex) for haptic working memory no matter whether the difference in features of memoranda needs to be memorized in the task or not. Over 400 SI neurons were also recorded in monkeys well-trained to discriminate two memoranda in the haptic-haptic DMS task for comparison of delay firing of SI neurons between the two different working memory tasks used in this study. The similarity observed in those two situations suggests that working memory uses already-existing memory apparatus by activating it temporarily. Our data also suggest that, through training (repetitive exposure to the stimulus), SI neurons may increase their involvement in the working memory of the memorandum.

A study of feature integration in haptic working memory

A study of feature integration in haptic working memory

Different haptic working memory stores for length and roughness

Different haptic working memory stores for length and roughness

Patterned firing of parietal cells in a haptic working memory task

Abstract Cells in the somatosensory cortex of the monkey are known to exhibit sustained elevations of firing frequency during the short-term mnemonic retention of tactile information in a haptic delay task. In this study, we examine the possibility that those firing elevations are accompanied by changes in firing pattern. Patterns are identified by the application of a pattern-searching algorithm to the interspike intervals of spike trains. By sequential use of sets of pattern templates with a range of temporal resolutions, we find patterned activity in the majority of the cells investigated. In general, the degree of patterning significantly increases during active memory. Surrogate analysis suggests that the observed patterns may not be simple linear stochastic functions of instantaneous or average firing frequency. Therefore, during the active retention of a memorandum, the activity of a 'memory cell' may be characterized not only by changes in frequency but also by changes in pattern.