Do “mudsplashes” induce tactile change blindness?

Neural correlates of perceptual texture change during active touch

Introduction

Texture changes occur frequently during real-world haptic explorations, but the neural processes that encode perceptual texture change remain relatively unknown. The present study examines cortical oscillatory changes during transitions between different surface textures during active touch.

Methods

Participants explored two differing textures whilst oscillatory brain activity and finger position data were recorded using 129-channel electroencephalography and a purpose-built touch sensor. These data streams were fused to calculate epochs relative to the time when the moving finger crossed the textural boundary on a 3D-printed sample. Changes in oscillatory band power in alpha (8-12 Hz), beta (16-24 Hz) and theta (4-7 Hz) frequency bands were investigated.

Results

Alpha-band power reduced over bilateral sensorimotor areas during the transition period relative to ongoing texture processing, indicating that alpha-band activity is modulated by perceptual texture change during complex ongoing tactile exploration. Further, reduced beta-band power was observed in central sensorimotor areas when participants transitioned from rough to smooth relative to transitioning from smooth to rough textures, supporting previous research that beta-band activity is mediated by high-frequency vibrotactile cues.

Discussion

The present findings suggest that perceptual texture change is encoded in the brain in alpha-band oscillatory activity whilst completing continuous naturalistic movements across textures.

Cost of Dual-Task Performance in Tactile Perception Is Greater for Competing Tasks of the Same Type

This study examines dual-task performance in the tactile modality and tests whether dual-task cost depends on task type. Experiment 1 involved competing tasks of the same type, using a primary localisation task on the left hand and a secondary localisation task on the right hand. In Experiment 2, the primary task on the left hand remained the same, while an intensity discrimination task was used as the secondary task on the right hand. Subjects in both experiments completed three conditions: the primary task alone, a dual-task condition, and the primary task with the secondary stimulus present but no response required. Across both experiments, performance on the primary task was best when it was presented alone, and there was a performance decrement when the secondary stimulus was present but not responded to. Performance on the primary task was further decreased when participants had to respond to the secondary stimulus, and the decrease was larger when the secondary task was localisation rather than discrimination. This result indicates that task type in the tactile modality may modulate the attentional cost of dual-task performance and implies partially shared resources underlie localisation and intensity discrimination.

Tactile, Visual, and Crossmodal Visual-Tactile Change Blindness: The Effect of Transient Type and Task Demands

OBJECTIVE

The present study examined whether tactile change blindness and crossmodal visual-tactile change blindness occur in the presence of two transient types and whether their incidence is affected by the addition of a concurrent task.

BACKGROUND

Multimodal and tactile displays have been proposed as a promising means to overcome data overload and support attention management. To ensure the effectiveness of these displays, researchers must examine possible limitations of human information processing, such as tactile and crossmodal change blindness.

METHOD

Twenty participants performed a unmanned aerial vehicle (UAV) monitoring task that included visual and tactile cues. They completed four blocks of 70 trials each, one involving visual transients, the other tactile transients. A search task was added to determine whether increased workload leads to a higher risk of change blindness.

RESULTS

The findings confirm that tactile change detection suffers in terms of response accuracy, sensitivity, and response bias in the presence of a tactile transient. Crossmodal visual-tactile change blindness was not observed. Also, change detection was not affected by the addition of the search task and helped reduce response bias.

CONCLUSION

Tactile displays can help support multitasking and attention management, but their design needs to account for tactile change blindness. Simultaneous presentation of multiple tactile indications should be avoided as it adversely affects change detection.

APPLICATION

The findings from this research will help inform the design of multimodal and tactile interfaces in data-rich domains, such as military operations, aviation, and healthcare.

The Development and Evaluation of Countermeasures to Tactile Change Blindness

OBJECTIVE

The goal of the present study was to develop and empirically evaluate three countermeasures to tactile change blindness (where a tactile signal is missed in the presence of a tactile transient). Each of these countermeasures relates to a different cognitive step involved in successful change detection.

BACKGROUND

To date, change blindness has been studied primarily in vision, but there is limited empirical evidence that the tactile modality may also be subject to this phenomenon. Change blindness raises concerns regarding the robustness of tactile and multimodal interfaces.

METHOD

Three countermeasures to tactile change blindness were evaluated in the context of a highly demanding monitoring task. One countermeasure was proactive (alerting the participant to a possible change before it occurred) whereas the other two were adaptive (triggered after the change upon an observed miss). Performance and subjective data were collected.

RESULTS

Compared to the baseline condition, all countermeasures improved intramodal tactile change detection. Adaptive measures resulted in the highest detection rates, specifically when signal gradation was employed (i.e., when the intensity of the tactile signal was increased after a miss was observed).

CONCLUSION

Adaptive displays can be used to counter the effects of change blindness and ensure that tactile information is reliably detected. Increasing the tactile intensity after a missed change appears most promising and was the preferred countermeasure.

APPLICATION

The findings from this study can inform the design of interfaces employing the tactile modality to support monitoring and attention management in data-rich domains.

Tactile warning signals for in-vehicle systems

The last few years have seen growing interest in the design of tactile warning signals to direct driver attention to potentially dangerous road situations (e.g. an impending crash) so that they can initiate an avoidance maneuver in a timely manner. In this review, we highlight the potential uses of such warning signals for future collision warning systems and compare them with more traditional visual and auditory warnings. Basic tactile warning signals are capable of promoting driver alertness, which has been demonstrated to be beneficial for forward collision avoidance (when compared to a no warning baseline condition). However, beyond their basic alerting function, directional tactile warning signals are now increasingly being utilized to shift the attention of the driver toward locations of interest, and thus to further facilitate their speeded responses to potential collision events. Currently, many researchers are focusing their efforts on the development of meaningful (iconic) tactile warning signals. For instance, dynamic tactile warnings (varying in their intensity and/or location) can potentially be used to convey meaningful information to drivers. Finally, we highlight the future research that will be needed in order to explore how to present multiple directional warnings using dynamic tactile cues, thus forming an integrated collision avoidance system for future in-vehicle use.

Tactile “Change Blindness” in the Detection of Vibration Intensity

A variety of data rich complex domains stand to benefit from the introduction of tactile displays that offload the visual and auditory information channels. Yet, a better understanding of factors that affect tactile information processing is needed to ensure the robustness of these interfaces. Recent research has shown, for example, that the sense of touch can be affected by phenomena that are analogous to visual change blindness, which describes the surprising difficulty in detecting changes to a visual scene when these changes coincide with masking stimuli or blank inter-stimulus intervals. To date, tactile change blindness has been demonstrated only for changes in the number of body locations where vibrations were presented. The present study examined whether change blindness is observed also in the context of detecting changes in vibration intensity and whether the introduction of a secondary task during vibrotactile presentations exacerbates these effects. The findings show that a 300-ms vibrotactile masking stimulus and a 600-ms “mudsplash” sequence of stimuli significantly degrade performance in detecting coincident intensity changes, as do intensity changes that occur gradually instead of abruptly. Change detection was significantly worse in dual-task (vs. isolation) conditions for only the “mudsplash” presentations. Implications of these effects for the design of tactile displays that encode information in vibration intensity are discussed.

Recognition of Asymmetric Alterations to Pictures of Cats: Effects of Method of Alteration and Type of Change in Elderly Subjects

Recognition of environmental changes is essential in everyday life. In this study, recognition of animate objects by elderly people was examined with various methods (introduction, restoration) and types (addition, deletion) of change. For restoration, deletions and additions were produced by eliminating features from pictures and reintroducing the deleted features, respectively. In introduction, additions and deletions were produced by adding and deleting features from original pictures. 37 subjects ( M age = 74 yr.) viewed each card for 10 sec. (learning phase) and were then asked (test phase) whether they had viewed the card in the learning phase and to rate their confidence in their answer. Percentage correct rejection and confidence ratings were higher for introductions compared to restorations and for deletions compared to additions. Findings are similar to those in young adults and children, which indicates developmental robustness of asymmetric effects in recognition of animate objects.

Tactile and Multisensory Spatial Warning Signals for Drivers

The last few years have seen many exciting developments in the area of tactile and multisensory interface design. One of the most rapidly-moving practical application areas for these findings is in the development of warning signals and information displays for drivers. For instance, tactile displays can be used to awaken sleepy drivers, to capture the attention of distracted drivers, and even to present more complex information to drivers who may be visually-overloaded. This review highlights the most important potential costs and benefits associated with the use of tactile and multisensory information displays in a vehicular setting. Multisensory displays that are based on the latest cognitive neuroscience research findings can capture driver attention significantly more effective than their unimodal (i.e., tactile) counterparts. Multisensory displays can also be used to transmit information more efficiently, as well as to reduce driver workload. Finally, we highlight the key research questions currently awaiting further research, including questions such as: Are tactile warning signals really intuitive? Are there certain regions of the body (or in the space surrounding the body) where tactile/multisensory warning signals are particularly effective? To what extent is the spatial coincidence and temporal synchrony of the individual sensory signals critical to determining the effectiveness of multisensory displays? And, finally, how does the issue of compliance vs. reliance (or the 'cry wolf' phenomenon associated with the presentation of signals that are perceived as false alarms) influence the effectiveness of tactile and/or multisensory warning signals?

Tactile and visual distractors induce change blindness for tactile stimuli presented on the fingertips

Recent studies of change detection have revealed that people are surprisingly poor at detecting changes between two consecutively-presented scenes, when they are separated by a distractor that masks the transients typically associated with change. This failure, known as 'change blindness', has been reported within vision, audition, and touch. In the three experiments reported here, we investigated people's ability to detect the change between two patterns of tactile stimuli presented to their fingertips. The two to-be-compared patterns were presented either consecutively, separated by an empty interval or else by a tactile, visual, or auditory mask. Participants' performance was impaired when an empty interval was inserted between the two consecutively-presented patterns as compared with the consecutive stimulus presentation. Participants' performance was further impaired not only when a tactile mask was introduced between the two to-be-compared displays, but also when a visual mask was used instead. Interestingly, however, the addition of an auditory mask to an empty interval did not have any effect on participants' performance. These results are discussed in relation to the multisensory/amodal nature of spatial attention.