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

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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.

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 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.