Eye movements disrupt episodic future thinking

Remembering the past and imagining the future both rely on complex mental imagery. We considered the possibility that constructing a future scene might tap a component of mental imagery that is not as critical for remembering past scenes. Whereas visual imagery plays an important role in remembering the past, we predicted that spatial imagery plays a crucial role in imagining the future. For the purpose of teasing apart the different components underpinning scene construction in the two experiences of recalling episodic memories and shaping novel future events, we used a paradigm that might selectively affect one of these components (i.e., the spatial). Participants performed concurrent eye movements while remembering the past and imagining the future. These concurrent eye movements selectively interfere with spatial imagery, while sparing visual imagery. Eye movements prevented participants from imagining complex and detailed future scenes, but had no comparable effect on the recollection of past scenes. Similarities between remembering the past and imagining the future are coupled with some differences. The present findings uncover another fundamental divergence between the two processes

Exploring the relationship between grapheme colour-picking consistency and mental imagery

Previous research has indicated a potential link between mental imagery and synaesthesia. However, these findings are mainly based on imagery self-report measures and recruitment of self-selected synaesthetes. To avoid issues of self-selection and demand effects we recruited participants from the general population, rather than synaesthetes specifically, and used colour-picking consistency tests for letters and numbers to assess a "synaesthete-like" experience. Mental imagery ability and mental rotation ability were assessed using both self-report measures and behavioural assessments. Consistency in colour-picking for letters (but not numbers) was predicted by performance on the visual mental imagery task, but not by a mental rotation task or self-report measures. Using the consistency score as a proxy measure of grapheme-colour synaesthesia, we provide more evidence for the suggestion that synaesthetic experience is associated with enhanced mental imagery, even when participants are naïve to the research topic

Eye movements disrupt spatial but not visual mental imagery

It has long been known that eye movements are functionally involved in the generation and maintenance of mental images. Indeed, a number of studies demonstrated that voluntary eye movements interfere with mental imagery tasks (e.g., Laeng and Teodorescu in Cogn Sci 26:207–231, 2002). However, mental imagery is conceived as a multifarious cognitive function with at least two components, a spatial component and a visual component. The present study investigated the question of whether eye movements disrupt mental imagery in general or only its spatial component. We present data on healthy young adults, who performed visual and spatial imagery tasks concurrently with a smooth pursuit. In line with previous literature, results revealed that eye movements had a strong disruptive effect on spatial imagery. Moreover, we crucially demonstrated that eye movements had no disruptive effect when participants visualized the depictive aspects of an object. Therefore, we suggest that eye movements serve to a greater extent the spatial than the visual component of mental imagery

“In the mind’s eye” – Exploring the interaction between oculomotor behaviour and memory-related processes in ageing and neurodegeneration

Much of the rich internal world constructed by humans is derived from, and experienced through, visual mental imagery. Despite growing appreciation of visual exploration in guiding imagery-rich construction-based processes, extant theories of memory retrieval and prospection have yet to accommodate the precise role of visual mental imagery and corresponding oculomotor dynamics in the service of past and future-oriented thinking, particularly as we age and in the presence of neurodegenerative syndromes. This thesis comprises three experimental studies investigating these issues. Chapter 2 demonstrates distinct signatures of oculomotor behaviour during visual exploration and memory retrieval in younger and cognitively healthy older adults, as well as patients with Alzheimer’s disease or semantic dementia. In Chapter 3, I further demonstrate age-related changes in eye movement metrics during the endogenous construction of atemporal scenes in the absence of externally cued visual stimuli. Results suggest a shift away from the production of eye movements in older adults as a function of increasing task complexity as cognitive demands exceed working memory capacities. Finally, Chapter 4 expands on the preceding findings in the context of episodic future thinking. The temporal distance and the level of plausibility of hypothetical future events are found to influence participants’ performance by encouraging the elaboration of scenarios that are particularly rich in contextual detail in selected experimental conditions. The work presented in this thesis adds to the extant literature by demonstrating and characterising the relationship between oculomotor behaviour and imagery-rich construction-based processes. Future enquiries exploring the potential and diverse applications of oculomotor metrics to neuropsychological and clinical research will further elucidate the complex adaptive mechanisms supporting cognitive performance in both healthy ageing and neurodegeneration

Determinants and Restrictions of the Processing and Reorganization of Spatial Configurations in Visual Working Memory

Der Mensch interagiert in jedem Moment seines Lebens mit mehreren Objekten. Um mit einzelnen Objekten umgehen zu können, ist der Mensch auf die räumlichen Beziehungen zwischen den Objekten angewiesen, um ein Netzwerk gleichzeitig zu verarbeiten. zu speichern und zu aktualisieren. Dieses mentale Netzwerk wird als (globale) räumliche Konfiguration bezeichnet, die u.a. im visuellen Arbeitsgedächtnis auf der Grundlage der Positionen und Relationen der enthaltenen Objekte dargestellt wird. Bisherige Forschung hat gezeigt, dass räumliche Konfigurationen mental flexibel dargestellt werden und dass die Möglichkeit besteht, dass eine globale räumliche Konfiguration in einen relevanten und einen irrelevanten Teil aufgeteilt werden kann. Die vorliegende Dissertation knüpft an diese Annahme an mit dem Ziel, das Verständnis dieses Mechanismus einschließlich der Determinanten und Einschränkungen bei der Verarbeitung von räumlichen Konfigurationen im visuellen Arbeitsgedächtnis zu vertiefen. Ziel war es, die Organisation und Reorganisation von räumlichen Konfigurationen genauer zu betrachten. Mit Hilfe empirischer Testung mittels eines Paradigmas zur Erkennung von Positionswechseln sowie einer Untersuchung des Einflusses von Hinweisreizen und offener visuellen Aufmerksamkeit führte (und veröffentlichte) ich vier Experimentalserien mit insgesamt elf Experimenten und etwa 500 Teilnehmer*innen. Die Studien zeigten, dass der Mensch in der Lage ist, räumliche Konfigurationen zu reorganisieren und Informationen zu (ir-)relevanten Teilkonfigurationen zu reduzieren. Darüber hinaus schränkte die (Nicht-)Verfügbarkeit von Augenbewegungen und Kontextinformationen diesen Prozess ein, während andere Mechanismen wie die individuelle Arbeitsgedächtnis-Kapazitätsschwelle und die begrenzte Möglichkeit der offenen visuellen Aufmerksamkeit über verschiedene Verarbeitungsstufen hinweg den beschriebenen Konfigurationsvorteil nicht einschränkten. Ich habe mir verschiedene Determinanten und Einschränkungen angesehen, aber verallgemeinert sind Menschen in der Lage, eine globale räumliche Konfiguration in eine relevante Teilkonfiguration im visuellen Arbeitsgedächtnis umzuorganisieren, die durch einen informativen Hinweisreiz induziert wird. Wichtig ist, dass der Mensch Augenbewegungen benötigt, um diesen Prozess zu bewältigen. Ein vollständiger Verlust der Verfügbarkeit von Augenbewegungen konnte nicht kompensiert werden, aber mit einer teilweise eingeschränkten Möglichkeit der Blickbewegungen zeigten die Versuchsteilnehmer*innen immer noch einen Konfigurationsvorteil. Während also die Verarbeitung räumlicher Konfigurationen im Gedächtnis durch die Fähigkeit zur Durchführung von Verschiebungen der offenen visuellen Aufmerksamkeit gefördert wird, ist die Konfigurationsverarbeitung nicht davon abhängig, dass diese Verschiebungen während der gesamten Aufgabe auftreten. Zukünftige Forschung sollte diese Ergebnisse aufgreifen, um sich einem präziseren Verständnis der Verbindung zwischen dem visuellen System und dem damit verbundenen Arbeitsgedächtnis anzunähern. Zusammenfassend unterstützt und erweitert die vorliegende Dissertation die Idee einer eher flexiblen mentalen Repräsentation einzelner Objekte, die in einer (globalen) Raumkonfiguration angeordnet sind.Humans interact with several objects every moment of their lifetime. In order to process single objects, humans rely on inter-object relations to maintain and update a network of different objects at once. This mental network is called a (global) spatial configuration, which is also represented in visual working memory (VWM) based on the locations and relations of the objects contained. Previous research revealed that spatial configurations are supposed to be represented mentally flexible and there might be the possibility that a global spatial configuration can be split up into a relevant part and an irrelevant part. The present dissertation connects with this assumption, and the objective was to deepen the understanding of this mechanism including determinants and restrictions of the processing of spatial configurations in VWM. The aim was to have a closer look at the organization and reorganization of spatial configurations. With the help of empiric behavioral testing via a location change detection paradigm as well as an investigation of overt visual attention induced by eye movements and the influence of retro cues, I conducted four experimental series including eleven experiments and about 500 participants. This revealed that humans are able to reorganize spatial configurations and reduce information leading to (ir-)relevant partial configurations. Furthermore, the (non-)availability of eye movements and contextual information restricted this process whereas other mechanisms such as the individual VWM capacity threshold and limited possibility of overt visual attention across different processing stages did not restrict the configuration advantage described. I had a look at different determinants and restrictions, but in general, humans are able to reorganize a global spatial configuration into a relevant partial one in VWM, induced by an informative retro cue. Importantly, participants needed eye movements to handle this process. While a total enforced fixation reduced the configuration advantage heavily, participants showed a comparable one to free view conditions with a partially restricted fixation. Thus, whereas the processing of spatial configurations in VWM is boosted by the ability of performing shifts of overt visual attention, configurational processing does not rely on these shifts occurring throughout the task. Future research should investigate these findings in order to approach a more precise understanding of the link between the visual sensorium and VWM. In summary, this dissertation supports and extends the idea of a rather flexible mental representation of single objects arranged in a (global) spatial configuration