Page 28 - It' about time: Studying the Encoding of Duration
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                                An investigation of the spatial selectivity of the duration after-effect  Introduction Human observers can readily encode duration information from events that vary in duration, and use that information to guide their behavior (Fraisse, 1984; Gibbon, 1977). Especially in the sub-second range, accurate duration encoding is instrumental for many complex behaviors such as precise motor control (i.e. in activities such as sport and dance), speech recognition and generation, and 2 the processing of social cues (Ambadar, Cohn, & Reed, 2009; Buhusi & Meck, 2005; Diehl, Lotto, & Holt, 2004; Janata & Grafton, 2003; Mauk & Buonomano, 2004; Merchant & Georgopoulos, 2006; Schmidt, Ambadar, & Cohn, 2005). Recently, there has been a renewed interest in studying this temporal aspect of our behavior and the way in which our brain encodes this information. This has resulted in several different types of models on duration encoding that each propose different mechanisms for the encoding of duration (Gibbon, 1977; Ivry & Schlerf, 2008; Jones & Boltz, 1989; Karmarkar & Buonomano, 2007; Matell & Meck, 2004; van Wassenhove, 2009). A recent model suggests the involvement of duration-selective neurons in the processing of duration information (Becker & Rasmussen, 2007; Heron et al., 2012). Evidence for these models come from adaptation studies that demonstrate a duration after-effect following adaptation. For example, Heron et al. (2012) showed that adapting to the duration of a visual or auditory event causes the perceived duration of a subsequently presented event with a slightly different duration to be skewed away from the adapted duration. This pattern of repulsion following adaptation to duration occurred when both stimuli were of the same modality but not for different modalities, implicating modality specific processing of duration. Importantly, this duration after-effect only occurred when the adaptation duration was close to the tested duration, disappearing when the difference between the two stimuli exceeded ~1.5 octaves. As such, adaptation to duration resulted in a pattern of repulsion similar to that observed for other visual properties such as orientation, spatial frequency, and temporal frequency, which are known to be processed by groups of neurons that show feature selectivity (K. K. De Valois, 1977; R. L. De Valois, Albrecht, & Thorell, 1982; R. A. Smith, 1971). Similar results have been reported by studies investigating the effect of trial history on duration judgments (Becker & Rasmussen, 2007; Walker, Irion, & Gordon, 1981). These studies also show that presentation of a particular duration causes the perception of subsequent shorter or longer  27 


































































































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