8. What are the advantages and disadvantages of using a virtual reality environment to study the brain and behavior? Give examples of the way that virtual reality can be used in Psychology. What is meant by visual search? 11. Describe the Sprague and Ballard theory (Walter) of gaze control. What evidence is there to support the theory. Why is it useful? 12. Describe a follow up experiment you would do to extend or improve on Lab 4, indicating how would you interpret the possible outcomes.
What are the advantages and disadvantages of using a virtual reality environment to study the brain and behavior? -Can do experiments in naturalistic environments. Why is this important? -Control of stimulus. Important in complex environments. -Can do impossible manipulations. -Unrealistic in many ways: small field of view, latency of display following movement, stereo cues weak, other cues missing. Visual-vestibular conflict -Discomfort. -Environment might change the behavior - eg heavy helmet suppresses head movements.
Describe the Sprague and Ballard theory (Walter) of gaze control. What evidence is there to support the theory. Why is it useful?
Walter is a purely top-down model of gaze control. • Virtual Humanoid has a small library of simple visual behaviors: • Sidewalk Following • Picking Up Blocks • Avoiding Obstacles Sprague & Ballard (2003) Each behavior uses a limited,task-relevant selection of visual information from scene.
Walter learns where/when to direct gaze using reinforcement learning algorithm. litter obstacles sidewalk The model can predict the sequence of fixations that a human might make in a similar situation.
What evidence is there to support the theory. Why is it useful? Evidence: top down control – everyday experience – look at task relevant locations Shinoda experiment – change the task, change the fixation patterns. Evidence that gaze is learned – walking with rogue pedestrians, also Shinoda experiment Why useful?: Since model is formulated in terms of behavior in a complex environment, can directly compare performance of model and humans in complex settings. Explicitly test hypotheses and change model to better approximate human behavior.
What is meant by visual search? How does the visual system locate objects? Visual search is the process by which the visual system locates a target in a visual scene and either allocates attention to that region, or makes a saccade to the target. When a saccade is made. It is called “overt attention”. Wen a saccade does not occur it is called “covert attention”.
Give examples of the way that virtual reality can be used in Psychology. 1. A way of developing a theory of human behavior 2. Other applications: training/testing How are gestures integrated with speech? How is gaze used to express emotion? How is gaze/gesture used in social interactions? Understanding infant language acquisition How is gaze used in language learning? Understanding human movement control Medical training, patient education (need realistic videos) Armed forces training. Safe testing of therapeutic strategies. Make rehab more interesting.
Describe a follow up experiment you would do to extend or improve on Lab 4, indicating how would you interpret the possible outcomes.
To investigate whether change blindness is reduced by familiarity, need to run longer sessions, more subjects, more objects changing. Calculate fixation probability early and late in session. Increased fixation probability late in session indicates effect of familiarity. To investigate effect of visual memory on search need to measure fixations. Time is not sensitive enough. Need more stable objects that are continuously visible. Fewer search objects. Fix problem that some objects are visible from outside the room. Discount time between target fixated on TV and time to room.