Aphantasia, i.e., the inability to voluntarily form visual mental images, affects approximately 2 to 5 percent of the population and plays an important role in a more general debate revolving around the role of imagery for our cognition. This thesis investigates aphantasia by means of an interdisciplinary approach, combining insights from contemporary neuroscientific research with historical philosophical arguments, with a specific focus on the later philosophy of Ludwig Wittgenstein. A new theoretical concept, meta-imagination, is developed and it is argued that (...) the concept can explain why aphantasics perform successfully on a wide range of visual imagery tasks, thus providing important implications for the more general debate about the connection between imagery and cognition. (shrink)

This thesis investigates the relationship between eye movements, mental imagery and memory retrieval in four studies based on eye-tracking experiments. The first study is an investigation of eye movements during mental imagery elicited both visually and verbally. The use of complex stimuli and the development of a novel method where eye movements are recorded concurrently with verbal data enabled the above-mentioned relationship to be studied to an extent going beyond what previous research had been able to do. Eye movements were (...) found to closely reflect content and spatial layout while participants were listening to a spoken scene description, while they were describing the same scene from memory, and while they were describing a picture they had previously seen. This effect was equally strong during recall from memory irrespective of whether the scene visualised had originally been inspected visually by the participants or whether it was constructed whole-cloth from long-term memory. It was also found that eye movements "to nothing" appeared both when the participants were visualising scenes while looking at a blank screen and when they were doing so in complete darkness. The second study explored an effect frequently observed in the first study, involving a "scaling-down" during recall of participants' gaze patterns to an area smaller than that occupied by the stimulus encoded. It was found that this scaling effect correlated with spatial-imagery ability: the gaze patterns of participants with weaker spatial-imagery ability were closer in size to the encoded scene than the gaze patterns of those stronger in spatial-imagery ability. In the third study, the role of eye movements during mental imagery was investigated in four experiments where eye movements were prohibited during either the encoding phase or the recall phase. Experiments 1 and 2 showed that maintaining central fixation during visual or auditory encoding, respectively, had no effect on how eye movements were executed during recall. Thus, oculomotor events during recall are not reproductions of those produced during encoding. In Experiments 3 and 4, central fixation was instead maintained during recall. This turned out to alter and impair scene recollection, irrespective of the modality of encoding. Finally, in the fourth study, the functional role of eye movements in relation to memory retrieval was further investigated by means of direct eye-movement manipulation in the retrieval phase of an episodic-memory task. Four conditions were used: free viewing on a blank screen, maintaining central fixation, viewing within a square congruent with the location of the objects to be recalled, and viewing within a square incongruent with the location of the objects to be recalled. The results obtained show that gaze position plays an active and facilitatory role during memory retrieval. The findings from these studies are discussed in the light of current theories regarding eye movements during mental imagery and memory retrieval. (shrink)

Proponents of phenomenal intentionality share a commitment that, for at least some paradigmatically intentional states, phenomenal character constitutively determines narrow intentional content. If this is correct, then any two states with the same phenomenal character will have the same narrow intentional content. Using a twin-earth style case, I argue that two different people can be in intrinsically identical phenomenological states without sharing narrow intentional contents. After describing and defending the case, I conclude by considering a few objections that help to (...) further illustrate the problem. (shrink)