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Catherine E. Grafton Phd Thesis BINOCULAR VISION AND THREE-DIMENSIONAL MOTION PERCEPTION: THE USE OF CHANGING DISPARITY AND INTER-OCULAR VELOCITY DIFFERENCES Catherine E. Grafton A Thesis Submitted for the Degree of PhD at the University of St Andrews 2011 Full metadata for this item is available in Research@StAndrews:FullText at: http://research-repository.st-andrews.ac.uk/ Please use this identifier to cite or link to this item: http://hdl.handle.net/10023/1922 This item is protected by original copyright This item is licensed under a Creative Commons Licence Binocular Vision and Three-Dimensional Motion Perception: The Use of Changing Disparity and Inter-Ocular Velocity Differences Catherine E. Grafton Submitted for degree of Doctor of Philosophy Friday August 20th 2010 Thesis Declaration I, Catherine Grafton, hereby certify that this thesis, which is approximately 69,700 words in length, has been written by me, that it is the record of work carried out by me and that it has not been submitted in any previous application for a higher degree. I was admitted as a research student in October 2006 and as a candidate for the degree of PhD in November 2010; the higher study for which this is a record was carried out in the University of St Andrews between 2006 and 2010. date ..................... signature of candidate ................................ I hereby certify that the candidate has fulfilled the conditions of the Resolution and Regulations appropriate for the degree of PhD in the University of St Andrews and that the candidate is qualified to submit this thesis in application for that degree. date ..................... signature of supervisor ................................ In submitting this thesis to the University of St Andrews we understand that we are giving permission for it to be made available for use in accordance with the regulations of the University Library for the time being in force, subject to any copyright vested in the work not being affected thereby. We also understand that the title and the abstract will be published, and that a copy of the work may be made and supplied to any bona fide library or research worker, that my thesis will be electronically accessible for personal or research use unless exempt by award of an embargo as requested below, and that the library has the right to migrate my thesis into new electronic forms as required to ensure continued access to the thesis. We have obtained any third-party copyright permissions that may be required in order to allow such access and migration, or have requested the appropriate embargo below. The following is an agreed request by candidate and supervisor regarding the electronic publication of this thesis: Embargo on both printed copy and electronic copy for the same fixed period of 2 years on the following ground: publication would preclude future publication; date ...............................signature of candidate ................................... signature of supervisor ……………………………………… Acknowledgements Firstly, I would like express my gratitude to my supervisor, Julie Harris, for inviting me to work with her in the Vision Lab at St. Andrews, and for her continued support and inspiration. I have also had the pleasure of working with Paul Hibbard throughout my undergraduate and post-graduate time at St. Andrews. All members of the St. Andrews Vision Lab have contributed to my work, through direct feedback, pilot trials or general discussion, including Dhanraj Vishwanath, Lisa O’Kane, Harold Nefs, Vit Drga, Katharina Zeiner, Louise O’Hare, Stephane Clery, George Lovell, Peter Scarfe and Ross Goutcher. Experiment 6 of this thesis was administered by Sebastian Hutchinson, who I would like to thank for doing the leg-work that saved me many vital hours. Of course, my gratitude also goes out to the many observers who donated their time and effort to contribute to this research. It is not enough to say that this couldn’t have been done without them. Thanks also goes to Eric Bowman and Mike Oram for their input on the statistical analyses performed in this thesis, the workshop guys for being on hand and for patiently resuscitating lifeless laptops. I would like to express my gratitude to the school of Psychology at St. Andrews for being my second home for 8 years and giving me a superb education as well as providing me with the facilities to conduct my research. I am also indebted to the EPSRC that funded my research. The Scottish Vision Group is also worthy of mention as they have allowed me to express my ideas and research and given extensive feedback and discussion. i There are many non-academics who have helped me through the process of this thesis. My parents have been a great source of support, and there’s no more that they could have done for me over the years. My brother, Josh, has also been a huge help, taking calls at all hours for purposes of tech-support, and confidence boosting. There have been many friends and house-mates that have contributed to this work in their own way, in particular, the band has been a great help over the last year (Graeme Crawford, Al McQueen, Bruce Norton and Alf). I would also like to thank Tina Tassadaq-Kiratli, who has always been a wonderful friend, but has surpassed herself with the proof-reading of this thesis. Last, but by no means least, I would like to thank Doug Zabel, for his years of love, support and laughter. ii Abstract This thesis investigates the use of binocular information for motion-in-depth (MID) perception. There are at least two different types of binocular information available to the visual system from which to derive a perception of MID: changing disparity (CD) and inter-ocular velocity differences (IOVD). In the following experiments, we manipulate the availability of CD and IOVD information in order to assess the relative influence of each on MID judgements. In the first experiment, we assessed the relative effectiveness of CD and IOVD information for MID detection, and whether the two types of binocular information are processed by separate mechanisms with differing characteristics. Our results suggest that, both CD and IOVD information can be utilised for MID detection, yet, the relative dependence on either of these types of MID information varies between observers. We then went on to explore the contribution of CD and IOVD information to time- to-contact (TTC) perception, whereby an observer judges the time at which an approaching stimulus will contact them. We confirmed that the addition of congruent binocular information to looming stimuli can influence TTC judgements, but that there is no influence from binocular information indicating no motion. Further to this, we found that observers could utilise both CD and IOVD for TTC judgements, although once again, individual receptiveness to CD and/or IOVD information varied. Thus, we demonstrate that the human visual system is able to process both CD and IOVD information, but the influence of either (or both) of these cues on an individual’s perception has been shown to be mutually independent. iii iv Contents 1. General Introduction 1 1.1 Binocular Information 1 1.2 Binocular Vision and Depth Perception: A Brief History 2 1.3 Binocular Disparity: Definitions 6 1.3.1 Absolute Binocular Disparity 6 1.3.2 Relative Binocular Disparity 8 1.3.3 Small Angle Approximations 10 1.4 Binocular Vision and Depth Perception: Evidence 12 1.5 Motion-In-Depth (MID) 15 1.5.1 Looming 15 1.5.2 Horizontal Vergence 17 1.5.3 Changing Disparity (CD) 21 1.5.4 Inter-Ocular Velocity Differences (IOVD) 22 1.6 MID Information from Random Dot Stimuli 24 1.6.1 Random-Dot Stereograms (RDS) 25 1.6.2 Dynamic Random Dot Stereograms (DRDS) 26 1.6.3 Temporally Correlated Random Dot Stereograms (TCRDS) 27 1.7 Evidence for Isolation of CD and IOVD Information 28 1.8 Specific Mechanisms for CD and IOVD Processing? 29 1.9 Evidence for the Use of CD and IOVD Cues 31 1.9.1 MID Detection 32 1.9.2 Speed Discrimination 35 1.9.3 Summary 37 1.10 Statement of Motivation 37 1.11 Aims of Thesis 38 2. Relative Binocular Motion-in-Depth Information 41 2.1 Introduction 41 2.1.1 Absolute and Relative Information 41 2.1.2 Relative vs. Absolute MID Perception 42 2.1.3 Relative vs. Absolute Binocular Depth Perception 44 2.1.4 Relative vs. Absolute 2-D Motion Perception 45 2.1.5 Aims 46 2.1.6 Rationale 47 v Binocular Vision and 3-D Motion Perception 2.1.7 Predictions 51 2.2 Methods 53 2.2.1 Apparatus 53 2.2.2 Observers 53 2.2.3 Stimuli and Conditions 54 2.2.3.1 Target stimuli 54 2.2.3.2 Noise 55 2.2.3.3 Reference stimuli 55 2.2.4 Procedure 56 2.2.5 Data and Analysis 57 2.3 Results 57 2.3.1 Strong vs. Weak Target-Reference Combinations 58 2.3.2 Individual Target-Reference Combinations 59 2.3.3 RDS 61 2.3.4 DRDS 61 2.3.5 TCRDS 63 2.3.6 Differences Between Target Types 64 2.3.7 Discarded Data 66 2.4 Discussion 66 2.4.1 Evidence of Target-Reference Combination Effects 66 2.4.2 Evidence of Separate Processes for IOVD and CD Information 68 2.4.3 Experimental Design 70 2.4.4 Relative Depth vs. Relative 2-D motion 71 2.4.5 Reference Stimulus Assumptions 73 2.5 Conclusions 74 3. Time-to-Contact: A General Introduction 75 3.1 Synopsis 75 3.2 TTC 75 3.3 Tau Theory 76 3.3.1 General Tau Theory 77 3.3.2 Relative Rate of Expansion 78 3.3.3 Optical vs.
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