Perception, Change blindness and Inattentional blindness

Question 1

What is the subject matter of psychophysics

Answer 1

The study of the relationship between the physical features of stimuli and our psychological experience of them

Question 1

What are the typical definitions of sensation and perception?

Answer 1

Sensation - physical feeling caused by having one or more of the sense organs stimulated

Perception - the brain interprets data from our senses to provide info about the environment

Question 2

Why is it said that our brains experience the world indirectly? … What is transduction?

Answer 2

transduction is when physical energy gets converted into neural activity!

• brains expereince the world indirectly because the sense organs convert stimulation through neural impulses

Question 3

Do objects have colour? Why?

Answer 3

NO, objects absorbs certain wavelengths of light and reflects others, wavelengths are energy and colours are created by our nervous system in response to them.

Question 4

Explain why perception can be viewed as a constructive process

Answer 4

because what we experience is due to the energy outside of us and what we percieve, and the transformation of this energy is due to our perceptual and cognitive systems.

Question 5

Define change blindness and inattentional blindness

Answer 5

change blindness - inability to detect large changes in the visual environment following a momentary distraction (blink)

Inattentional blindness - inability to detect an unusual object that is present as your mind is elsewhere

Question 6

How did Levin et al (2002) show that we exaggerate our ability to detect visual changes?

Answer 6

• asked observers to watch videos of 2 people in a restraunt
• in one video the plates change from red to white, in another a scarf worn by one person dissapeared
• observers said that 46% wouls notice the colour change, 78% would notice the scarf change
• in actual fact 0% of observers noticed the change

Question 7

Describe what is called ‘change blindness blindness’

Answer 7

• our wildly optimistic beliefs about our ability to detect visual changes
• avoiding change blindness

Question 8

What are the three differences between change blindness and inattentional blindness

Answer 8

1) TARGET DETECTION IN CHANGE BLINDNES PARADIGMS ARE OFTEN HARD EVEN WITH INSTRUCTIONS

2) CHANGE BLINDNESS REQUIRES MEMORY

3) INNATENTIONAL BLINDNESS ONLY OCCURS IN TASKS THAT REQUIRE GOAL DIRECTED ATTENTION e.g talking on the phone

Question 9

What is a saccade

Answer 9

rapid movement of the eye between fixation points

Question 10

According to Jensen et al (2011), successful change detection requires 5 steps; what are they?

Answer 10

1) DIRECT ATTENTION TO CHANGE LOCATION

2) PRE CHANGE VISUAL STIMULUS AT THE CHANGE LOCATION MUST BE ENCODED INTO MEMORY

3) POST CHANGE VISUAL STIMULUS AT THE CHANGE LOCATION MUST BE ENCODED INTO MEMORY

4) THE PRE AND POST CHANGE REPRESENTATIONS MUST BE COMPARED

5) CONSCIOUSLY RECOGNIZE THE DISCREPANCY

failure in these steps can lead to change blindness

Question 11

Why does EK8 say that change blindness underestimates visual processing?

Answer 11

visual processing isnt really taking place as its mainly uncoscious processing

Question 12

What are the two major competing theories of change blindness that provide partial answers to the question ‘what causes change blindness’?

Answer 12

1) THE ATTENTIONAL APPROACH

2) THE IMPORTANCE OF PERIPHERAL VISION

Question 13

Summarise the Hollingworth and Henderson (2002) study in the role of attention in change blindness.

Answer 13

• used eye tracking
• ppts study images for 20s in view of a memory test, asked to press a button each time they notice change.

RESULTS:
-fixation of object prior to the change is necassary for change detection
- 40% fixation on fixated object, so 60% blindness

Question 14

What is visual crowding

Answer 14

The inability to recognize objects in peripheral vision due to the presence of neighbouring objects

Question 15

Describe the study by Sharan et al into why change blindness may occur due to limitations of peripheral vision

Answer 15

• put change detection tasks as easy medium or hard on the basis of how quickly observers detecte change.
• ppts were told that there will be changes
• 2 images, then asked if the 3rd image is the same as the other 2.

RESULTS:
- 85% accuracy when it was easy and medium
- change detection performance was good even when it was well into peripheral vision, peripheral vision plays a major role in determining change detection performance.

Question 16

Why does category similarity matter

Answer 16

you must be able to know what diffferent categories mean e.g if the task was to point out number u need to know what numbers are

Question 17

Describe the study by Most et al (2001) (black and white shapes for inattentional blindness)

Answer 17

• black and white shapes on either side of the line, white cross going from side to side, ppts asked to count how many times black shapes hit each other, many dont realise the white cross going side to side

Question 18

Why are the results of perush and melara significant in demonstrating Barack Obama Blindness

Answer 18

absense of visual awareness to a single object