Daniele Cassaghi
Affiliation: University of Turin
Category: Philosophy
Keywords: Specious present, Temporal perception, Temporal consciousness
Date: Wednesday 3rd of September
Time: 18:30
Location: Room 154 (154)
View the full session: Temporal Consciousness
The doctrine of the specious present—according to which the contents of our perceptual acts are temporally extended and thus make us aware of time intervals rather than single instants—has been the target of numerous critiques over the past decade. Some of these, such as those put forward by Valtteri Arstila (2017), are based on empirical evidence.
Arstila’s starting point is the experiments conducted by Vincent Di Lollo (1980). In each condition, Di Lollo presented his participants with a pair of sets of twelve dots, with a 10 ms interstimulus interval. If the two sets of dots were superimposed, the resulting configuration would be a 5 × 5 matrix of dots with one missing. The task was to identify the missing dot in each condition. The various conditions differed only in respect to the duration of the first set of dots: it was presented for 10, 40, 80, 120, 160, and 200 ms, respectively. According to Di Lollo, success in the task depends on the ability to have both sets of dots “available to perception,” meaning roughly that all twenty-four dots should be present together in the same perceptual content. Results show that when the first set of dots lasts less than 100 ms, subjects succeed; with longer onset stimuli, they fail.
Elaborating on Di Lollo’s own view, Arstila contends that these results are inconsistent with the specious present view. Indeed, if a specious present theorist wishes to explain successful trials in Di Lollo’s task by claiming that both sets of dots are present to the subject within the same specious present, they find themselves unable to explain the failures. Given the mere 10 ms interstimulus interval, both sets of dots are part of the same perceptual content in every condition. Thus, the objector concludes, subjects should always succeed in Di Lollo’s task.
In this talk, I will offer an explanation of Di Lollo’s experiments that is compatible with the doctrine of the specious present. I will show that this objection against the specious present view is viable only if an unmotivated assumption is taken for granted in the background—namely, the idea that the specious present is “homogeneous in terms of information or resolution” throughout the represented interval. By this, I mean the following: according to this “homogeneity thesis,” all objects within the specious present appear with the same amount of detail and property determination. Furthermore, the properties of objects occurring at different temporal locations within the specious present are assumed to be presented with the same degree of determinability. The “homogeneity thesis” should be rejected in order to account for Di Lollo’s findings within a specious present perspective, I will show.
The “Patchy specious present” view, in fact, negates the “homogeneity thesis.” According to my view, there is a difference in information, resolution, and determination among the properties of objects presented at different temporal locations within the specious present. Properties of objects at the “center” of the specious present appear to subjects with the highest amount of determination, information, and resolution. Properties of objects at the periphery—namely, in the past coda of the specious present—appear much less determinate (and much more determinable). An easy analogy can be made with the spatial visual field: it is well known that objects in the focal center appear full of details and determinate properties, while objects in the periphery do not appear full of details because their properties are far less determinate. The specious present works in the same way with respect to different temporal locations.
The Patchy specious present explains why people fail at Di Lollo’s task. Indeed, in every scenario, the onset set of dots lies in the past coda of the specious present anytime the second set of dots appears. Thus, the information about the internal configuration of the first set of dots may no longer be available when the second set of dots appears, even though a residual amount of information about the first twelve dots (i.e., the occurrence of a determinable set of dots) is still retained in the specious present. This, in turn, explains why subjects report perceiving the succession of the two matrices, even though they do not identify the missing dots (Hogben and Di Lollo 1973).
Obviously, an explanation for the success cases should also be provided. I will show how the specious present theorist can deploy the very same suggestion advanced by Di Lollo to explain success (Shardlow 2019). He proposes that our perceptual system is endowed with a mechanism that “artificially” extends the duration of a stimulus up to 100 ms anytime this stimulus is briefer than 100 ms. The idea, he maintains, is that our downstream identification processes require stimuli longer than 100 ms to function properly. So, this mechanism proposed by Di Lollo helps with the identification of briefer stimuli.
For our purposes, it is useful to notice that the activation of this mechanism with the onset twelve dots, which are briefer than 100 ms, might make the onset dots last long enough to become simultaneous with the second set of dots. Thus, when this mechanism activates, both sets of dots appear simultaneously in the “center” of the specious present, allowing subjects to identify the missing dots accordingly.
Notably, the strategy I propose to explain Di Lollo’s task is the same one deployed by the anti-specious present theorist Arstila (2018). He also explains failures in terms of information loss in our perceptual content—albeit, in his view, due to a change in perceptual content—and success in virtue of Di Lollo’s mechanism.
After discussing Di Lollo’s experiments, I will offer some brief remarks on a series of related issues. Firstly, I will explain why, in my view, the “Patchy specious present” is not committed to the claim that change is experienced less vividly than other properties like color (see Dainton 2023). Secondly, I will clarify more precisely how my view differs from that of Phillips (2011), who was the first to propose a “determinable” specious present in my sense.