Taking the rough with the smooth: aging effects on tactile surface texture perception

Lead Research Organisation: University of Birmingham
Department Name: School of Psychology

Abstract

Over the course of a day most of us handle numerous items, grasping and manipulating them, at the same time running our hands and fingers over their surfaces. Sometimes we touch and handle objects that are fully visible in order to carry out a particular task, for instance, picking up money from a countertop. At other times we may seek to identify an object, or some part of it, by its shape or surface texture when it cannot be seen, for example, when trying to retrieve money in a wallet. The sensations evoked by touching surfaces (e.g. smooth vs. textured, soft vs. hard, sticky vs. slippery) and the effect of products that change the feel of touched objects (e.g. in washing dishes, fabrics, hair) can be key to their usability and commercial success.
Despite the importance of surface feel, only now are we beginning to understand how humans explore surfaces, what is the physics of the interaction between finger and surface, what is the information that receptors in skin and muscles capture about surface texture, and how surface sensations are affected by multisensory signals. Recent neuroscientific studies, including research in our lab, indicate how, not only brain areas that respond to touch are involved in texture perception, but also regions that primarily process visual and auditory information contribute to texture perception, even in the absence of visual and auditory stimuli. These findings help our understanding of previous research showing that the feel of a touched surface can be influenced by concurrent sounds and images.
Surface exploration is an active process that may involve static or dynamic touching with the finger tip pressing (e.g. to determine hardness or temperature) or sliding (e.g. to determine roughness or stickiness) over the surface. In either case, good control of finger tip movement (position and force) is required, along with suitable cognitive resources to define exploration strategies appropriate to the surface possibilities. Given a number of touch components, each liable to variability or 'noise', are involved in active touch for surface perception, this can lead to deterioration in overall performance if, as is likely, the noise increases with age. On the other hand, redundancy may contribute to substitution of one process for another (or a change in their relative weighting), which can reduce the impact of deterioration in one or more of the components. Aging touch is therefore of both theoretical and practical importance in understanding touch.
In this project the Universities of Birmingham and Nottingham have come together with Procter & Gamble to understand how information from touch is actively generated, processed and combined with information from other senses (hearing, vision) and how these processes change later in life. Research into aging effects on perception has largely focused on vision and hearing. However, age-related changes in both peripheral and central aspects of touch have been observed. This project includes behavioural and brain imaging studies of active touch to develop a model of how information is actively sought and combined to sense texture and how these processes are adjusted to compensate for age-related changes. Furthermore the findings and model will be extended to a consumer product-testing environment to examine the effects of cleaning products on tactile surface perception.
In summary, the ways in which we use active touch to perceive surface texture are not fully understood and the effects of aging are relatively unknown. The proposed project addresses these topics by detailing surface perception on a wide scale (ranging from smooth surfaces to relatively coarse surfaces made of gratings with lines spaced hundreds of microns apart and including naturally occurring and manufactured surfaces with various coatings affecting frictional resistance to sliding) using behavioural, brain imaging and modeling approaches in healthy young and aging populations.

Technical Summary

The proposed project is a collaboration involving expertise in academia and industry to understand how information from multiple sources and senses is combined to perceive surface texture and how this process changes with age. Different textures, including roughness (ranging over smooth, fine, coarse) and surface friction (ranging from slippery to sticky), are known to be perceived via a combination of tactile and proprioceptive information mediated by receptors in skin and muscle. However, there is no formal model of how movement, tactile and proprioceptive inputs are integrated. Moreover, little is known about how other sensory cues contribute to the final percept, despite recent compelling evidence that touch is a multisensory experience that changes throughout the lifespan. This project combines behavioural and brain imaging experiments to relate changes in tactile surface perception with age to changes in skin biomechanics and to develop a Bayesian model of texture-based perceptual decisions. The model will be extended to a consumer product-testing environment to measure how texture is used to judge cleanliness in dish washing.
Three partners, Universities of Birmingham and Nottingham and Procter & Gamble, will take part in 3 work packages. WP 1 will measure the behavioural effects of varying texture stimuli on older and younger adults' performance on perceptual decisions. This will be the first step towards a model of the factors influencing texture perception. WP 2 will measure neural activity in brain regions selective for touch, auditory and visual stimuli as well as in 'higher' cognitive regions. This will allow us to understand the level of multisensory influence on texture perception, and if this varies as sensory abilities change with age. WP 3, will assess how texture perception is related to concepts of cleanliness and washing in order to evaluate how well our models generalize to everyday situations and product development.

Planned Impact

Procter & Gamble (P&G) has a formal collaboration with the University of Birmingham in the area of product formulation and engineering. Formulated products contain a wide range of different active ingredients that can interact with each other in a synergistic or detrimental manner. The products' chemistry, in conjunction with the processing of the product is what ultimately determines the products' chemical and physical properties and the consumer's perception when using a product or interacting with surfaces treated with the product. Understanding the process of how the consumer interacts with the products and the surfaces on which the products act is therefore seen as critical by P&G as they seek to optimize product design for consumer benefit. The proposed research area opens up a novel opportunity for collaboration with psychologists at Birmingham and Nottingham, which can help P&G in correlating how product characteristics are perceived by the product user's senses, especially touch. Thus, a major impact of this project will be commercial, with important additional impact envisaged in health/clinical settings and in public engagement and information.
Industrial/Economic:
Dish washing. We expect a direct contribution to product design and improvement from the understanding of the consumer experience of using washing products, in terms of product design (given improved understanding of touch sensing abilities) in order to supplement the designer's traditional mix of implicit knowledge and inspiration. The chosen target for short and medium term impact is via hand dishwashing liquid. Active touch is used every day to assess dirt or grease (consider running your finger over a shelf, or plates in the washing up). Cleanliness of dishes is important, both for those living independently, but also for those living in supported or cared for environments. As touch declines with age, it may be increasingly difficult to discriminate surface cleanliness with touch and there may be an increased reliance on vision to compensate. Products and strategies can be designed to 'fit' with these changes. The improvement of food preparation surface and eating utensil cleanliness is particularly critical in healthcare or nursing settings but also in the home. Improvements in the ease of cleaning would reduce costs for healthcare and improve well-being.
Coping with aging effects on touch. The effects of aging on active touch are not well understood. The methods for studying active touch developed in the project and the findings about aging effects on skin biomechanics and multisensory integration for surface perception will be explored with stakeholder groups including those working in elderly product design, for example, developing skin creams to help with skin hydration. Increasing the understanding of normal capacity and changes with age will also have implications for assessment in diagnosis and treatment of diseases affecting touch including peripheral vascular problems (eg diabetes), and disorders of the central nervous system (eg stroke). The incidence of many of these diseases increases with age so understanding the typical ranges of performance will aid in identifying the non-typical individual. Furthermore this will also aid in the planning of rehabilitation for those with impairments, for instance by encouraging use of alternate sensory information or different movement patterns in activities of daily living.
Public awareness.
There is general awareness of the decline of vision (at least to the extent of increased spectacle use) or hearing (hearing aids), but there is little knowledge of the typical decline of touch. Many older people will experience declines in tactile sensitivity so it may be helpful and reassuring, both to them and their carers, to understand normal changes that occur with aging and it may be useful to understand the role of the other senses in reducing the impact of the changes in touch.

Publications

10 25 50
 
Description Procter and Gamble studentship
Amount £48,500 (GBP)
Organisation Procter & Gamble 
Department Procter & Gamble (United Kingdom)
Sector Private
Country United Kingdom
Start 05/2019 
End 04/2022
 
Description Responsive mode
Amount £1,100,000 (GBP)
Funding ID BB/R003971/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 01/2018 
End 12/2020
 
Title Functional imaging of brain activity during applicaiton of various textures to the finger 
Description A standardised procedure has been developed for assessing brain activity during tactile contact with surfaces of varying roughness presented either with static pressure or sliding across the finger pad. 
Type Of Material Physiological assessment or outcome measure 
Year Produced 2018 
Provided To Others? No  
Impact Data are currently being collected to contrast brain activity during toiuch in young and lder adults 
 
Title Texture discrimination methods 
Description A robust psychophysical method using 2 interval forced choice discrimination with contact force measurement and finger motion capture has been developed for testing texture discrimination in young and older adult participants. 
Type Of Material Physiological assessment or outcome measure 
Year Produced 2018 
Provided To Others? No  
Impact Data are nw being collected to contrast young and older adult performance 
 
Description Aging touch industrial collaboration 
Organisation Procter & Gamble
Department Brussels Innovation Centre
Country Belgium 
Sector Private 
PI Contribution The taking the rough with the smooth project involves 13 studies, grouped into 3 work packages (WPs). WP1, with 7 studies, focuses on psychophysics and modelling of texture discrimination (O1,O3), WP2, with 3 studies, centres on brain function through functional imaging and electrical stimulation (O2). WP3, with 3 studies, translates the research findings into understanding surface texture perception in the applied context of discriminating changes in surface coating due to the use of surfactants (washing up liquid) to remove grease and deposits when hand washing plates (O4). WP3 is being run in collaboration with Procter & Gamble BIC.
Collaborator Contribution Procter & Gamble BIC will peovide access to research facilities at their consumer testing centre at BIC
Impact A workshop on Aging touch was run by the academic team at BIC in Autumn 2019
Start Year 2018
 
Description Collaborative Visit to P & G 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact A visit by Uni of Nottingham and Uni Birmingham to Protor and Gamble in Brussels. The visit included expert presentations on the project, seminars on business skills by industry leaders and discussions on industry activities and future works
Year(s) Of Engagement Activity 2019
 
Description Conference oral presentation: Roughness perception spans the hands: Roberts R, Wing A 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Title: Roughness perception spans the hands:
Authors: Roberts R, Wing A
Oral presentation vie teleconferncing at Psychonomic Society TActile Research Group November 2020 meeting
Using 2-IFC and AME tasks with spatial gratings in the .4 to 2.0 mm range we show the perception of roughness at one digit (the thumb) is biased by roughness at a second, distraction digit (the index finger) on the same hand. This extends the findings of previous studies using dots and sandpaper to spatial gratings. The novel finding is that the distraction finger bias occurs between hands. The magnitude of the effect is reduced in the discrimination task
Year(s) Of Engagement Activity 2020
 
Description Conference poster presentation: Early sensory processing of tactile texture in the brain: Loomes AR, Roberts RD, Kwok HF, Allen, H, Wing AM. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Title: Early sensory processing of tactile texture in the brain
Loomes AR, Roberts RD, Kwok HF, Allen, H, Wing AM.
Poster presentation vie teleconferencing at Society for Neuroscience Connectome January 2021 meeting

Tactile processing of surface texture is important in handling and recognition of everyday objects. Psychophysical studies support a duplex theory in which texture perception is mediated by vibration coding (driven by relative motion between digit and stimulus and underpins the perception of very fine textures) and spatial coding (does not require relative motion and underlies coarse texture perception). We examined differences in activation of primary and secondary somatosensory, auditory and visual cortex associated with fine and coarse tactile spatial gratings applied by sliding or touching (moving vs static contact) on the index finger pad. We found regions, contralateral to the stimulated digit, in BA1 in S1, OP1, OP3 and OP4 in S2, and TE1.0 in auditory cortex, but not in visual cortex, which were significantly more activated by moving textures. Regions in brain areas activated by vibrotactile stimuli (including auditory cortex) were also modulated by whether or not the gratings moved. In a control study we showed that this contrast persisted even when the salience of the static condition was increased by using a double touch. These findings constitute the first evidence from functional brain imaging of cortical substrates for the duplex theory of texture perception and provide further support for multisensory cortical mechanisms in tactile processing.
Year(s) Of Engagement Activity 2021
 
Description Conference poster presentation: The Effects on Vision on Static-touch Coarse Roughness Discrimination: Li, M. S., Di Luca, M., & Roberts, R. D 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Title: The Effects on Vision on Static-touch Coarse Roughness Discrimination
Authors: Li, M. S., Di Luca, M., & Roberts, R. D
Poster presentation vie teleconferncing at Experimental Psychology Society Jauary 2021 meeting
Non-discrepant visual input improves roughness discrimination. Effects of mismatching visuotactile signals are dependent on tactile sensitivity.
Year(s) Of Engagement Activity 2021
 
Description Conference poster presentation: Two-point discrimination task in young and elderly: a psychophysical and computational study: Deflorio D., Di Luca M., Wing, A.M. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Title: Two-point discrimination task in young and elderly: a psychophysical and computational study
Authors: Deflorio D., Di Luca M., Wing, A.M.
Poster presentation vie teleconferncing at Experimental Psychology Society Jauary 2021 meeting

Tactile sensitivity is affected by age, as shown by the deterioration of spatial acuity assessed in 2-points discrimination task (Kalisch et al.,
2009). This is thought to be partly due to age-related anatomical and morphological changes including a decrease in mechanoreceptors density (Garcia-Piqueras et al., 2019) and reduced skin elasticity (van Kuilenburg et al., 2013). However, because recording the nerve fibers is technically challenging, the relationship between these age-related factors, the resulting activity of tactile receptors, and perception is not fully understood.
This study addresses: (1) whether spatial information is present at peripheral level (2) whether skin elasticity and afferent density can quantitatively
account for the performance of the two age-groups
Year(s) Of Engagement Activity 2021
 
Description Creepy crawling 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Poster and demonstrations exploring touch with Professor Alan Wing and his BBSRC project team including Al Loomes and Roberta Roberts from the School of Psychology. How does sense of touch differ across different species and what does this tell us? What do would touch be like for zombies versus werewolves and why might they be different?
 
Year(s) Of Engagement Activity 2018
 
Description Exploring touch through the lifespan 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact The changes in perception of touch, and how it relates to other senses, is not well understood. There is considerable evidence that coarse and fine textures are perceived via different brain mechanisms. For instance, fine texture seems to make use of vibration sensors whereas coarse textures are more likely to use sensors specific to shape. This leads to different predictions about how multisensory input might be combined. This workshop focuses on how older people might combine information across senses to understand touch. This activity is first designed to communicate our work and engage with our users.
The workshop (max 3 hours) involves approximately 10 participants discussing their experience of touch and how it changes with age. The event is be facilitated by a creative artist (http://grahamelstone.mystrikingly.com/#creative-education) who is experienced with similar events.
Year(s) Of Engagement Activity 2020
 
Description Science in the Park 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Science in the Park is an event for everyone, held in a stately home in Nottingham. We exhibited demonstrations from our project to the public.
Year(s) Of Engagement Activity 2019
URL http://nottsbsa.org/science-park-2019/science-fair-science-park-2019/