Page 51 - It' about time: Studying the Encoding of Duration

Chapter 3 that event (Block et al., 2010; Mattes & Ulrich, 1998; Tse et al., 2004). However, these studies do not address the role of attention in situations where multiple sources of duration information are present. This is surprising, as several theories of duration encoding have stressed the role of attention in gating duration information for subsequent encoding (Gibbon et al., 1984; Meck, 1984; Pariyadath & Eagleman, 2007; van Rijn et al., 2014; Zakay & Block, 1997). In the current study, we investigated the role of attention in the selective encoding of duration. We presented participants with multiple duration signals and investigated whether attending one source of duration information modulated duration encoding. We used duration-adaptation (Heron et al., 2012) to probe duration encoding and measured whether allocating attention towards one of multiple sources of duration information modulated the resulting duration after-effect (DAE). The DAE is a repulsive after-effect in which adaptation to a specific duration in one modality leads to a repulsive shift in the perceived duration of post-adaptation stimuli presented in the same modality (Heron et al., 2012; Li, Yuan, & Huang, 2015; Maarseveen, Hogendoorn, Verstraten, & Paffen, 2017; Shima et al., 2016). For example, adaptation to an 800 ms visual stimulus will lead to subsequent presentations of a visual stimulus with a shorter duration (i.e. 400 ms) to be perceived as even shorter, and presentations of a visual stimulus with a longer duration (i.e. 1200 ms) as even longer. This after- effect of adapting to duration is interpreted to reflect selective adaptation of duration-tuned channels as a result of the repeated encoding of their preferred duration (Heron et al., 2012). In line with this interpretation, modulation of the DAE is taken to reflect changes in the strength of encoding of the presented duration information. In Experiment 1, participants adapted to two asynchronous streams of stimuli, each consisting of repetitions of a single duration stimulus that lasted either 200 or 800 ms (Figure 1). To probe the modulatory effect of attention, participants were instructed to detect duration oddballs in either the 200 or the 800 ms stream. Following adaptation, we measured the resulting DAE using a duration judgment task, in which participants compared the duration of an auditory reference (400 ms) to that of a visual test stimulus. We predicted that if attention modulates duration encoding, adaptation to the attended duration should increase relative to the adaptation to the unattended duration. In other words, attending the 800 ms durations should lead to a 400 ms test stimulus being perceived as shorter, compared to attending the 50