  Coming from a very different direction, Grush has argued (2005b, 2006, 2007, 2016) that Retentional models have a distinct advantage over Extensional models when it comes to accommodating certain ‘temporal illusions’. The relevant category of cases are those where a stimuli occurring later than a time t affects the character of what is perceived as occurring at t itself; the so-called flash-lag effect and the phi-phenomenon fall into this category. These instances of (apparent) retro-active causation are only found occurring over brief intervals, but they are certainly as puzzling as they are intriguing. Grush suggests that Retentional models can handle such cases by virtue of the fact that what is perceived as occurring at t need not remain constant from one specious present to another. So, for example, a particular spot of light might be perceived as motionless in a specious present S1 occurring very shortly after t, and that same spot might be perceived as being in motion in a later specious present S2. This option is not available to Extensional theorists – since on this view the spot is represented just once – and as a consequence there will be conflicting perceptual experiences of what is occurring at t: the spot will be perceived (impossibly) as both stationary and in motion. However, there are replies available to the Extensional theorist. It takes some time for our perceptual systems to produce an experience in response to a stimuli; perhaps our perceptual systems make use of this time to work out (as it were) a single coherent response to ambiguous or conflicting stimuli. Accordingly, rather than the spot’s being experienced as both stationary and as moving, it is experienced just the once, in motion. For more on the relevant illusions, Grush’s argument, and the responses available to the Extensionalist see Section 3 of the supplementary document  Husserl, the Brain and Cognitive Science,  and the supplementary document   Interpreting Temporal Illusions.