Habituation in acoustic startle reflex: Individual differences in personality Angel Blanch a,b, ⁎, Ferran Balada a,b,c , Anton Aluja a,b a Department of Psychology, University of Lleida, Spain b Institute of Biomedical Research (IRB Lleida), Spain c Department of Psychobiology, Institute of Neurosciences, Autonomous University of Barcelona, Spain abstract article info Article history: Received 21 June 2013 Received in revised form 20 December 2013 Accepted 2 January 2014 Available online 9 January 2014 Keywords: Habituation Startle reflex Personality This study analyzed the relationship of individual differences in personality with habituation in the acoustic star- tle response (ASR). Data from nine trials in ASR to white noise bursts and a personality questionnaire based on the alternative big five personality approach were modelled with a latent growth curve (LCM) including inter- cept and slope habituation growth factors. There was a negative correlation between the intercept and slope, in- dicating that individuals with higher initial ASR levels had also a more pronounced and faster decrease in the ASR. Contrary to expectations, Extraversion and Sensation Seeking did not relate with habituation in ASR. Neuroticism and Aggressiveness related asymmetrically with the habituation rate in ASR. Higher levels of Neuroticism were related with faster habituation, whereas higher levels of Aggressiveness were related with slower habituation. Further studies with the LCM should be undertaken to clarify in a greater extent the association of personality with habituation in ASR. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Habituation is an intriguing and complex process. As an elementary form of learning, it takes place at the neural level, and implies a progres- sive decrement in a given response issued after a repeated stimulation. The dual-process theory is the most influential systematization of this phenomenon, with the key assumption of two intertwined processes in the central nervous system: habituation (decline of the response), and sensitization (intensification of the response). There are two important stimulus parameters, intensity and frequency, that influence both pro- cesses in different ways. Higher intensity levels tend to rule sensitization, whereas higher frequencies influence habituation in a greater extent. Within this framework, it is also useful to distinguish between short- term habituation, a decay of the response in the same experimental ses- sion, and long-term habituation, a decay of the response between differ- ent experimental sessions (Groves and Thompson, 1970; Thompson and Spencer, 1966). Later refinements about habituation have suggested that the identi- fication of influential pathways might be of use to clarify the cellular and neuronal mechanisms embedded within the habituation processes (Rankin et al., 2009; Thompson, 2009). On the other hand, a psycholog- ical constructionist approach to human emotion advocates for the fact that biological explanations of behaviour such as brain activity, chemical circuitries, or synaptic connections should not replace the psychological accounts for the wide array of mental experiences. Albeit physiological attributes are certainly important elements in the configuration of emotion and mental states, they would not be specific for instance to emotions such as interest, happiness, sadness, anger, disgust, or fear (Barrett et al., 2007; Miller, 2010). Recent evidence from the neuroim- aging literature supports this psychological constructionist scheme in contrast to a locationist approach, which defends the correspondence of emotion categories with different brain regions (Lindquist and Barrett, 2012; Lindquist et al., 2012). Thus, complex psychological de- scriptors might be outlined at a strongly wired network level, suggest- ing that emotion categories would emerge from non-specific general brain systems. Nevertheless, it has also been argued that neuroimaging studies tend to manage the effects of individual differences as noise that needs to be dealt with because of the emphasis on brain activation ar- rangements assumed as common across individuals (Hamann and Harenski, 2004; Murphy et al., 2012). Moreover, the association of spe- cific brain activation with emotional and cognitive processing has been suggested to be strongly leveraged by individual differences such as personality, mood, dispositional affect, sex, and genotype, whereby these would be important modulators of the neurobiological basis of emotion and cognition (Canli et al., 2004; Hamann and Canli, 2004). Bearing this in mind, habituation in responses to emotional and cog- nitive processing is a neurobiological process influenced by individual differences in personality, despite the paucity of studies addressing this particular topic. In this work, we analyzed the association of habit- uation in acoustic startle reflex (ASR) and broad personality dimensions with a latent curve model (LCM). At present, there are only a few studies International Journal of Psychophysiology 91 (2014) 232–239 ⁎ Corresponding author at: Department of Pedagogy and Psychology, Faculty of Education Science, University of Lleida, Avda de l'Estudi General, 4, 25001 Lleida, Catalonia, Spain. Tel.: +34 973706529. E-mail address: ablanch@pip.udl.cat (A. Blanch). 0167-8760/$ – see front matter © 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ijpsycho.2014.01.001 Contents lists available at ScienceDirect International Journal of Psychophysiology journal homepage: www.elsevier.com/locate/ijpsycho