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

在一天的过程中，我们大多数人都要处理许多东西，抓住并操纵它们，同时我们的手和手指在它们的表面上滑动。有时，我们触摸和处理完全可见的物体是为了完成一项特定的任务，例如，从台面上捡起钱。在其他时候，我们可能会在看不见的情况下，通过物体的形状或表面纹理来识别物体或物体的某些部分，例如，当我们试图从钱包里取出钱时。触摸表面所引起的感觉（如光滑与纹理，软与硬，粘与滑）以及改变触摸物体感觉的产品效果（如洗碗，织物，头发）可能是其可用性和商业成功的关键。尽管表面感觉很重要，但直到现在我们才开始了解人类是如何探索表面的，手指和表面之间相互作用的物理原理是什么，皮肤和肌肉中的受体捕获的关于表面纹理的信息是什么，以及表面感觉是如何受到多感官信号的影响的。最近的神经科学研究，包括我们实验室的研究，表明，即使在没有视觉和听觉刺激的情况下，不仅对触觉做出反应的大脑区域参与了纹理感知，而且主要处理视觉和听觉信息的区域也参与了纹理感知。这些发现有助于我们理解之前的研究，即触摸表面的感觉会受到同时出现的声音和图像的影响。表面探索是一个主动的过程，可能包括用指尖按压（例如确定硬度或温度）或滑动（例如确定粗糙度或粘性）在表面上进行静态或动态触摸。在任何一种情况下，都需要良好的指尖运动控制（位置和力量），以及适当的认知资源来定义适合表面可能性的探索策略。考虑到许多触觉组件，每个都容易受到变化或“噪音”的影响，涉及到表面感知的主动触摸，如果随着年龄的增长，噪音可能会增加，这可能会导致整体性能的恶化。另一方面，冗余可能有助于用一个过程代替另一个过程（或改变它们的相对权重），这可以减少一个或多个组件恶化的影响。因此，老化触觉在理解触觉方面具有理论和实践的重要性。在这个项目中，伯明翰大学和诺丁汉大学与宝洁公司合作，了解来自触觉的信息是如何积极地产生、处理并与来自其他感官（听觉、视觉）的信息结合在一起的，以及这些过程在以后的生活中是如何变化的。关于衰老对感知的影响的研究主要集中在视觉和听觉上。然而，已经观察到与年龄相关的触觉外围和中心方面的变化。该项目包括对主动触觉的行为和脑成像研究，以建立一个模型，说明信息是如何被积极地寻找和组合到感觉纹理上的，以及这些过程是如何调整以补偿与年龄相关的变化的。此外，研究结果和模型将扩展到消费者产品测试环境中，以检验清洁产品对触觉表面感知的影响。总之，我们使用主动触觉感知表面纹理的方式尚未完全了解，老化的影响也相对未知。拟议的项目通过在健康的年轻人和老年人群中使用行为、脑成像和建模方法，在大范围内详细描述表面感知来解决这些问题（从光滑表面到由相距数百微米的光栅制成的相对粗糙的表面，包括自然发生的和具有各种涂层的人造表面，这些涂层会影响摩擦阻力）。

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.