This document discusses perception and how the brain interprets sensory information from the external world. It explains that perception involves both bottom-up processing, where individual sensory inputs are constructed into a whole, as well as top-down processing, where prior knowledge and expectations influence perception. The document also discusses several optical illusions and a study showing cultural differences in susceptibility to the Muller-Lyer illusion, suggesting experiences shape an individual's perceptual tendencies.

1. Perception
How we interpret our world

2. IB Learning Outcomes
C9- With reference to relevant research
studies, to what extent is one cognitive
process reliable?
Key-Terms:
 Bottom-Up and Top-Down processing

3. Which Ball is Bigger?
How do you know?

4. What is Perception?
The process by which the brain organizes and
interprets sensory information.
 Takes in sensory information from our outside world and
gives it meaning.

5. Sensory Receptors
1. Information collected through the Eyes, Ears,
Nose, Skin, Tongue (Sensory Receptors).
2. Information processed in the brain.

6. Visual Cues
Distance & Size (Depth)
Boundaries & Edges
Figures & Backgrounds
Color & Shading (Texture)
Placement
Others?

7. How I Perceive Annie the
Anniversary Dog

8. Types of Processing
Bottom-Up Processing
Top-Down Processing

9. Bottom-Up Processing
Data Driven Processing
Processing incoming individual pieces of
sensory data and constructing them into a
whole. (Parts into Whole)
Starting point of perception.

10. Bottom-Up Processing Example

11. Bottom-Up Perception
Lets break it down…
Thousands of Yellow and Brown Lego Bricks
 Blades of grass
Fences
A crowd of people in the background
 Start with a pile of legos at the Bottom (Individual
elements) and you must build them Up (Whole)

12. Top-Down Processing
Knowledge/Context/Hypothesis Driven
Processing
 Processing based on our knowledge about the
world.
We perceive what we are expecting to perceive

13. Schema Theory
A mental representation of knowledge stored in the
brain. A Schema can be seen as a network of
knowledge, beliefs, and expectations about
particular aspects of the world.
We use our schemas to help us process
information from our environments and they
impact how we interpret that information.

14. Top-Down Processing

15. Optical Illusions
How does Bottom-Up and Top-Down
processing help explain the following
illusions?

18. Group 1

19. Group 2

20. What do you see?

21. Perceptual Sets
Perceptual Sets: Sets formed when
expectations influence perceptions

22. Perceptual Sets

24. The Müller-Lyer Illusion

25. Segall et al. (1966)
Aim: To determine if perception of the Muller-Lyer
Illusion is universal.
 Method: With the help of cultural anthropologists,
showed the Muller-Lyer Illusion to members of 17
different groups and recorded their ability to
identify the length of the lines.
 Non-Western Tribes: Uganda, Congo, Central Australia,
Nigeria. (and others)
 Western Groups: European South Africans, Americans

26. Segall et al. (1966)
Findings:
Westerners are significantly more susceptible to
the illusion than individuals from non-western
cultures.
Some non-western tribes experienced no
problems with the illusion.
Conclusion: Experiences (not necessarily
culture) impact the ability of individuals to
perceive particular illusions using depth of
field.

27. Carpentered World Theory
Living in a world with many structured angles
make westerns more likely to use depth of field
to guide their perception than non-westerners.

28. Discussion Questions
To what extent is our perception reliable?
 If our perception has failed us before, can we ever
trust it again?