Agreeable Smellers and Sensitive Neurotics – Correlations among Personality Traits and Sensory Thresholds Ilona Croy 1,2 *, Maria Springborn 1 , Jo ¨ rn Lo ¨ tsch 3 , Amy N. B. Johnston 4 , Thomas Hummel 1 1 Smell and Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany, 2 Department of Psychosomatic Medicine, University of Dresden Medical School, Dresden, Germany, 3 Pharmazentrum Frankfurt/Zentrum fu ¨ r Arzneimittelforschung, Entwicklung und Sicherheit, Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany, 4 Clinical Neuroscience, Eskitis Institute of Cell and Molecular Therapies, Griffith University, Nathan, Australia Abstract Correlations between personality traits and a wide range of sensory thresholds were examined. Participants (N = 124) completed a personality inventory (NEO-FFI) and underwent assessment of olfactory, trigeminal, tactile and gustatory detection thresholds, as well as examination of trigeminal and tactile pain thresholds. Significantly enhanced odor sensitivity in socially agreeable people, significantly enhanced trigeminal sensitivity in neurotic subjects, and a tendency for enhanced pain tolerance in highly conscientious participants was revealed. It is postulated that varied sensory processing may influence an individual’s perception of the environment; particularly their perception of socially relevant or potentially dangerous stimuli and thus, varied with personality. Citation: Croy I, Springborn M, Lo ¨ tsch J, Johnston ANB, Hummel T (2011) Agreeable Smellers and Sensitive Neurotics – Correlations among Personality Traits and Sensory Thresholds. PLoS ONE 6(4): e18701. doi:10.1371/journal.pone.0018701 Editor: Hiroaki Matsunami, Duke University, United States of America Received September 27, 2010; Accepted March 15, 2011; Published April 27, 2011 Copyright: ß 2011 Croy 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: The authors were free to direct analysis and reporting without any influence from sponsors. There was no editorial direction or censorship from any sponsors. Competing Interests: The authors have declared that no competing interests exist. * E-mail: ilona.croy@tu-dresden.de Introduction Personality research often explores the development of and influences on personality traits, characteristics that are sometimes defined as ‘‘enduring tendencies or habitual patterns of behavior, thought, and emotion’’ [1]. Many models of personality, exploring and defining specific traits have been developed, some more complex than others. The five-factor model of personality [2] enables a description of human personality in a relatively economi- cal way. It is intended to supply a comprehensive taxonomy of traits using only five basic categories- extraversion, neuroticism, agreeableness, openness and conscientiousness and thus provides opportunity to effectively explore potential influences on the development of personality traits and their relationships with other parameters such as sensory ability. Indeed, one of the most interesting areas in current personality research deals with the problem of how personality may be shaped during development. What induces people to differ from each other in the way they think, feel or behave in certain situations? The last few decades of personality research and clinical praxis have seen the emergence of nature-nurture-interaction hypotheses in answer to such fundamental developmental issues [3,4]. These suggest that basic tendencies are constitutionally predisposed but are also developed and shaped during experiences with and within the environment. Thus, the environment enables subtle shaping of apparently underlying genetic components of personality. Prior to this study almost no research has explored the influence of variation in sensory thresholds on individual differences in personality, even though research has demonstrated that there are significant individual differences in visual, auditory, olfactory and gustatory capacity (e.g. [5,6,7]) as well as in tolerance to pain ([8,9,10]. Thus, this study set out to systematically examine whether there maybe relationships between sensory thresholds and inter-individual personality differences. Sensory ‘constitution’ could be an individual variable associated with and helping to form personality characteristics. This hypo- thesis is seated in the notion that people do not have an objective picture of the world surrounding them, but rather, a person- specific filtered one. The varying capacities of peoples’ sensory systems would form one part of a possible ‘sensory-filter’ system applied by all to their perception of their environment. Such a stable, rigid filter could profoundly influence an individual’s perception of the world and therefore influence their thoughts, behavior and emotions relative to their environment. In addition, the attention given by an individual to a particular stimuli or to a particular form of sensory input could also shape such a ‘sensory- filter’. Attention to particular kinds of sensory stimuli could be modulated by many factors including by current emotional state. For example, people suffering from posttraumatic stress disorder (PTSD) have been shown to process unpleasant, potential harming, stimuli in a preferred way [11,12]. ‘Thought’ experiments can be used to graphically illustrate this ‘sensory-filter’ concept. If one lived with increased strong feelings of pain, one might perceive the world as a rather unpleasant place. A major behavioral motivation for such a person would include reduction of pain, so that harm avoidance would become highly PLoS ONE | www.plosone.org 1 April 2011 | Volume 6 | Issue 4 | e18701