Unmasking emotion: Exposure duration and emotional engagement MAURIZIO CODISPOTI, a MICHELA MAZZETTI, a and MARGARET M. BRADLEY b a University of Bologna, Bologna, Italy b University of Florida, Gainsville, Florida Abstract Effects of exposure duration on emotional reactivity were investigated in two experiments that parametrically varied the duration of exposure to affective pictures from 25–6000 ms in the presence or absence of a visual mask. Evaluative, facial, autonomic, and cortical responses were measured. Results demonstrated that, in the absence of a visual mask (Ex- periment 1), emotional content modulated evaluative ratings, cortical, autonomic, and facial changes even with very brief exposures, and there was little evidence that emotional engagement increased with longer exposure. When information persistence was reduced by a visual mask (Experiment 2), differences as a function of hedonic content were absent for all measures when exposure duration was 25 ms but statistically reliable when exposure duration was 80 ms. Between 25–80 ms, individual differences in discriminability were critical in observing affective reactions to masked pictures. Descriptors: Emotion, Masking, Duration, Affect, Pictures, Affective perception Motivationally relevant cues elicit a broad range of emotional responses, involving autonomic, cortical, and subjective changes that reflect the motivational system that is engaged (i.e., defen- sive or appetitive) and its intensity of activation (Bradley & Lang, 2007). Many studies have found that when participants view pictures for a sustained period of time (e.g., 6 s), cortical and peripheral changes co-vary either with system engagement (va- lence) or with motive intensity (arousal). For instance, compared to neutral pictures, both pleasant and unpleasant pictures prompt a marked positive late potential (LPP; e.g., Codispoti, Ferrari, & Bradley, 2007; Cuthbert, Schupp, Bradley, Birbau- mer, & Lang, 2000), as well as larger skin conductance changes (e.g., Lang, Greenwald, Bradley, & Hamm, 1993). On the other hand, corrugator electromyographic (EMG) activity varies with affective valence, with larger corrugator EMG responses when viewing unpleasant, compared to pleasant or neutral, pictures (e.g., Lang et al., 1993). For a variety of methodological, conceptual, and theoretical reasons, however, experimental exposure to affective pictures can vary from brief to sustained durations. In this study, we explore effects of exposure duration on emotional reactivity when pic- tures are presented from 25 ms to 6 s, comparing affective mod- ulation of the late positive potential of event-related potential (ERP), electrodermal responses, facial muscle activity, and eval- uative judgments. The resulting database provides information regarding whether brief exposures are sufficient to elicit affective reactions in a variety of response systems, as well as whether the magnitude of emotional reactivity increases or decreases as ex- posure duration changes. In studies that have explored effects of an exposure less than 6 s, evidence of affective modulation was evident in both the late positive potential (e.g., De Cesarei & Codispoti, 2006; Johnston & Wang, 1991; Kayser et al., 1997; Schupp, Jungho¨ fer, Weike, & Hamm, 2004) as well as in skin conductance change (e.g., Codi- spoti, Bradley & Lang, 2001; Globisch, Hamm, Esteves, & O ¨ hman, 1999). Nonetheless, in the absence of a direct compar- ison across a variety of exposure durations, it is not clear whether presentation duration modulates the magnitude of emotional reactivity, or whether there is a minimal duration necessary to elicit measurable changes. In the current study, we assessed the effects of exposure duration on affective responding by para- metrically varying exposure duration from 25–6000 ms while measuring evaluative, facial, and autonomic responses, as well as the late positive component of the ERP. In the absence of a perceptual masking stimulus that imme- diately follows picture presentation, visual processing can con- tinue, due to information persistence (Coltheart, 1980; Loftus, Duncan, & Gehrig, 1992). Thus, even with the brief durations previously explored (e.g., 100 ms), it is possible that affective modulation reflects this facet of perceptual processing. To more specifically assess the effects of exposure duration alone, in Ex- periment 2 we reduced information persistence by presenting a visual pattern mask immediately following picture offset. Pictures were presented for either 25, 40, 50, 80, 150, 250, or 1000 ms and followed by a 1 s visual pattern mask, while evaluative, We thank Roberto Ceccanti, Rossella Cardinale, Roberta Amaduzzi, Michela Rendano, Chiara Barbarino, and Cristina Angeloni for helping with data collection. Address reprint requests to: Maurizio Codispoti, Department of Psychology, University of Bologna, Viale Berti Pichat, 5, 40127 Bologna, Italy. E-mail: maurizio.codispoti@unibo.it Psychophysiology, 46 (2009), 731–738. Wiley Periodicals, Inc. Printed in the USA. Copyright r 2009 Society for Psychophysiological Research DOI: 10.1111/j.1469-8986.2009.00804.x 731