Page 115 - It' about time: Studying the Encoding of Duration

Chapter 6 a situation in which the object becomes occluded, we could investigate the effect of temporal frequency content on the perceived duration of the occluded stimulus. If the temporal frequency content of the illusion-inducing stimulus is represented during occlusion, it should still influence the perceived duration of the event even when that object is no longer visible. In two experiments we found that (expected) temporal frequency content influenced the perceived duration of a stimulus while it was occluded. From this, we concluded that the representations of occluded objects contain a wide range of features derived from the period when the object was still visible, including information about both the static and dynamic properties of the object. Interestingly, the results reported in Chapter 5 also underscore the role of temporal frequency as an integral component of our perception of duration. Even under conditions when information about change is no longer present, a representation of this information is actively maintained and used to inform our perception of duration. Summary To summarize, we demonstrated that duration-tuned mechanisms: are located at a relatively late stage in the visual processing hierarchy (Chapter 2); rely on attention to effectively select duration information when multiple source of duration information are present (Chapter 3) and; encode duration based on the length of the sensory signal (Chapter 4). We conclude that duration is a high- level stimulus feature which is encoded via an effortful process which relies on attention to select relevant onset and offset information to encode duration. Together these studies demonstrate the value of using sensory adaptation and the duration channel model as a guiding framework for studying the encoding of duration. In addition, we demonstrated that temporal information is maintained during conclusion and discussed the importance of temporal frequency as a source of temporal information (chapter 5). In the following sections, we will discuss theoretical considerations and outstanding issues that are relevant for future research. Since the bulk of this dissertation focuses on duration perception, this discussion will focus on critically evaluating the role of the DAE and the duration channel model in studying and understanding the encoding of duration. 114