10. What is meant by visual search?

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14 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

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8. What are the advantages and disadvantages of using a virtual reality

environment
to study the brain and behavior
?
















9.
Give
examples of the way that virtual reality can be used in Psychology
.


10.
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?


Virtual Humanoid has
a small library of
simple visual
behaviors:


Sidewalk Following


Picking Up Blocks


Avoiding Obstacles


Each behavior uses a
limited,

task
-
relevant

selection of visual information from scene
.

Sprague & Ballard (2003)

Walter is a purely top
-
down model of gaze control.

Walter learns where/when to direct gaze using reinforcement

learning algorithm.

The model can predict

the sequence
of
fixations that a human might

m
ake in a similar situation.

obstacles

sidewalk

litter

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

c
ompare 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

a
nd 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.

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.


1. A
way of developing a theory of human behavior

2. Other
applications: training/testing


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

t
o 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.