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Temporal Illusions Subsequent to Movement

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Temporal Illusions Subsequent to Movement Temporal illusions subsequent to movement Kielan Nicholas Yarrow Submitted for the degree of Ph.D (Neurological Studies) from the University of London University College London ProQuest Number: 10014439 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest. ProQuest 10014439 Published by ProQuest LLC(2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. Microform Edition © ProQuest LLC. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 Abstract When saccadic eye movements are made to a silently ticking clock, observers sometimes think that the second hand takes longer than normal to move to its next position. For a short period, the second hand appears to have stopped; then, suddenly, it ticks on. This phenomenon is of intuitive interest as an experience that many people recognise, and formed the starting point of the research described here. A comparison methodology was employed in which subjects judged the perceived duration of a visual stimulus relative to that of subsequent stimuli. The duration of the first stimulus varied across trials, permitting the derivation of a matched time at which subjects felt the stimuli to be of equal duration. When the first stimulus was fixated immediately after a saccade, lower matched times were obtained relative to constant fixation conditions, indicating that subjective time had been stretched out. This effect is termed saccadic chronostasis. The methodology permitted accurate quantification of saccadic chronostasis under various task conditions. Manipulations explored include movement size, movement type (saccades of various types, hand/arm movements), the nature of the stimulus that is to be judged and its relationship to other perceptual objects. Key results include the illusion’s dependency upon both saccade size and the continuity of certain components of the visual scene. Similarities and important differences emerged when the paradigm was extended to arm movements (manual chronostasis). Chronostasis offers a novel insight into the integration of action and perception, with implications for theories of perceptual continuity across movements. It is an illusion of time, and must be dealt with by theories that seek to explain temporal perception, but also has more general relevance when considering the manner in which conscious experience emerges from a sequence of sensory events. These issues inform an initial characterisation of the effect. Table of contents Title page................................................................................................ 1 Abstract.................................................................................................2 Table of contents ....................................................................................3 Publications, collaborations and acknowledgements ........................5 Chapter 1. Introduction ................................................................... 6 Chapter 2. Saccadic chronostasis .................................................. 22 Chapter 3. Image discontinuities destroy saccadic chronostasis. 52 Chapter 4. Saccadic chronostasis and moving stimuli ................ 80 Chapter 5. Registration/dissociation between saccadic chronostasis and motor timing/tactile stimulation... 105 Chapter 6. Manipulations of saccade type and post-saccadic stimuli................................................... 130 Chapter 7. Manual chronostasis ...................................................... 157 Chapter 8. General discussion ........................................................ 186 References .............................................................................................. 217 Appendix A. The modified binary search algorithm .......................235 Appendix B. Timing issues in visual basic .......................................241 List of Tables Table 6.1 MOBS parameters for experiment 6a.......................... 134 Table 6.2 Mean standard deviations for experiment 6a ..............139 Table 8.1 Comparison of experimental manipulations ...............186 List of Figures Figure 1.1 Schematic of SET internal clock model .....................9 Figure 2.1 Schematic of experimental procedure (la)................ 27 Figure 2.2 Mean subjective seconds (la) ..................................... 30 Figure 2.3 Example logistic regression plot (la).........................31 Figure 2.4 Mean subjective seconds (Ib) ................................... 35 Figure 2.5 Mean subjective seconds (le) .................................... 39 Figure 2.6 Mean reaction time and error rates (Id) .................... 43 Figure 2.7 Mean subjective seconds (Id ) ................................... 45 Figure 2.8 Mean subjective seconds (la and Id, subgroup) ...... 46 Figure 3.1 Schematic of experimental procedure (2a) ............... 58 Figure 3.2 Mean subjective seconds and Weber ratios (2a) ...... 6? Figure 3.3 Mean subjective seconds (2b) ................................... 69 Figure 3.4 Mean subjective seconds (2d) ................................... 73 Figure 4.1 Schematic of motion/chronostasis interaction Accounts ...................................................................... 81 Figure 4.2 Mean subjective seconds (3a) ..................................... 88 Figure 4.3 Mean localisation errors (3b) ..................................... 93 Figure 4.4 Mean continuity points (3 c) ....................................... 99 Figure 5.1 Schematic of experimental procedure and predictions (4a) ............................................................ 108 Figure 5.2 Mean subjective seconds (4a) ..................................... 114 Figure 5.3 Mean tap contact times (4a) ....................................... 115 Figure 6.1 Mean subjective duration estimates (5a) ................... 137 Figure 6.2 Schematic of arousal based account of chronostasis. 140 Figure 6.3 Mean subjective seconds (5b) .................................... 147 Figure 6.4 Mean subjective seconds (5c) ..................................... 151 Figure 7.1 Schematic of experimental procedure (6a)................ 160 Figure 7.2 Examples of signal recordings (6a)........................... 164 Figure 7.3 Mean subjective seconds (6a) ..................................... 165 Figure 7.4 Mean subjective seconds (6b) ................................... 171 Figure 7.5 Block by block subjective seconds, by subject (6c).. 178 Figure 7.6 Overall subjective seconds, by subject (6c) .............. 179 Figure 7.7 Mean subjective seconds (6c) ..................................... 18? Figure 8.1 Schematic showing perceived position based on a flattened internal representation of eye position.... 193 Figure 8.2 Shematic showing perceived position when neurones remap their receptive fields ....................... 194 Publications, collaborations and acknowledgements Experiments la, Ib, le, Id, 2a and 2b bave previously been published in the following article: Yarrow K, Haggard P, Heal R, Brown P, Rothwell JCE (2001). Illusory perceptions of space and time preserve cross-saccadic perceptual continuity. Nature 414: 302-305. Experiment 6a was conducted in collaboration with Lisa Webster, and has also been included in her final project contributing towards the degree of MSc (Clinical Neuroscience; UCL). Experiment 6c was conducted in collaboration with Helen Johnston, and will also be included as part of her thesis for the degree of PhD (Psychology; UCL) I would like to thank my primary supervisor. Professor John C Rothwell, for providing the vital seed for this research while granting me the freedom to explore my own ideas, make my own mistakes, and hopefully learn from them. I would also like to thank my secondary supervisor. Dr Patrick Haggard, for numerous enlivening discussions. Both have shown a light touch while remaining available. Thanks also to Dr Kai V Thilo for introducing me to the modified binary search. Chapter 1 : Introduction The accurate representation of time is a fundamental requirement for humans. It underlies both perception within a dynamic environment and the production of co-ordinated behaviour. Timing is ubiquitous, woven into the fabric of sensory and motor processes, whether it is explicitly represented/controlled or arises indirectly as an emergent property of a given system. Despite its central role, time perception is not as well understood as sensory modalities like vision and touch, perhaps because we lack an obvious dedicated organ for its measurement. The research to be described in the bulk of this thesis relates to a particular illusion of timing that occurs in the context of movement and may therefore shed light upon perception in dynamic contexts. This illusion has not been described previously, so no substantial body of work is available to summarise at this point. The handful of experiments that appear of most direct relevance are dealt with in greater detail in the experimental chapters that follow. Here, a selective review of previous timing-related research is presented to provide some general orientation for the reader. The retrospective/prospective distinction in interval timing.
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