Dinse2 Abstract Cognitive and Tactile Factors Affecting Human Haptic Performance in Later Life Tobias Kalisch1,2*, Jan-Christoph Kattenstroth2, Rebecca Kowalewski2, Martin Tegenthoff1, Hubert R. 1 Department of Neurology, BG-Kliniken Bergmannsheil, Ruhr-University Bochum, Bochum, Germany, 2 Neural Plasticity Lab, Institute for Neuroinformatics, Ruhr- University Bochum, Bochum, Germany Background: Vision and haptics are the key modalities by which humans perceive objects and interact with their environment in a target-oriented manner. Both modalities share higher-order neural resources and the mechanisms required for object exploration. Compared to vision, the understanding of haptic information processing is still rudimentary. Although it is known that haptic performance, similar to many other skills, decreases in old age, the underlying mechanisms are not clear. It is yet to be determined to what extent this decrease is related to the age-related loss of tactile acuity or cognitive capacity. Methodology/Principal Findings: We investigated the haptic performance of 81 older adults by means of a cross-modal object recognition test. Additionally, we assessed the subjects’ tactile acuity with an apparatus-based two-point discrimination paradigm, and their cognitive performance by means of the non-verbal Raven-Standard-Progressive matrices test. As expected, there was a significant age-related decline in performance on all 3 tests. With the exception of tactile acuity, this decline was found to be more distinct in female subjects. Correlation analyses revealed a strong relationship between haptic and cognitive performance for all subjects. Tactile performance, on the contrary, was only significantly correlated with male subjects’ haptic performance. Conclusions: Haptic object recognition is a demanding task in old age, especially when it comes to the exploration of complex, unfamiliar objects. Our data support a disproportionately higher impact of cognition on haptic performance as compared to the impact of tactile acuity. Our findings are in agreement with studies reporting an increase in co-variation between individual sensory performance and general cognitive functioning in old age. Citation: Kalisch T, Kattenstroth J-C, Kowalewski R, Tegenthoff M, Dinse HR (2012) Cognitive and Tactile Factors Affecting Human Haptic Performance in Later Life. PLoS ONE 7(1): e30420. doi:10.1371/journal.pone.0030420 Editor: Daniel Goldreich, McMaster University, Canada Received September 19, 2011; Accepted December 15, 2011; Published January 23, 2012 Copyright: 2012 Kalisch et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This research was supported by Grants from the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) to HRD (Di 334/19-1, SFB 874) and MT (Te 315/4-1, SFB 874) and a Grant from FoRUM (F637-08) to TK. J-CK is a recipient of a stipend from the Allgemeiner Deutscher Tanzlehrerverband (ADTV). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: tobias.kalisch@rub.de Introduction Haptic perception Haptic object recognition is perfectly performed, countless times every day, as healthy adults can identify common and usual objects within 2–3 seconds with almost 100% accuracy [1]. Haptic perception is a process mediated by cutaneous and kinesthetic afferent subsystems [2]. A large number of mecha- noreceptors and thermoreceptors embedded in the skin as well as mechanoreceptors in muscles, tendons, and articulated joints provide the information necessary for the active exploration of objects and surface properties [3]. This manual exploration process is based on a number of so-called exploratory procedures, i.e., highly stereotypical hand-movements, which are associated with certain object properties [4,1]. Subjects who must recognize an object first employ a fast general exploratory procedure that provides an overview of multiple dimensions of the object. This overview is then used to decide which more specific exploratory procedures should be applied next in order to identify the object. The succession of selection and application of exploratory procedures will be repeated until the object is recognized [5]. Although vision is the primary sensory modality used by humans to explore and identify objects in their environment, haptic perception often provides the same information about certain characteristics of an object [6], as both modalities are based on the extraction of basic features such as the spatial arrangement of contours [7]. Macro geometric features such as object orientation, shape, and size, are predominantly processed by the visual system, even during haptic object exploration [8]. Visual and haptic object exploration are similarly impaired by changes in object characteristics such as orientation [9], size [10,11], and surface properties [12]. There is much converging evidence showing broad similarities between visual object recognition and haptic object recognition, which are a conse- quence of substantial overlaps in the higher-order neural resources PLoS ONE | www.plosone.org 1 January 2012 | Volume 7 | Issue 1 | e30420