1. Computational Model of Perception

2. Distal Stimulus (Information in the World)
Humans see only a sliver of light

3. Some reflected light gets to eye…
Distal Stimulus (Information in the World)
Light is reflected
Light is scattered
Light is absorbed
Some reflected light gets to eye…
A sliver of a sliver

4. Distal Stimulus (Information in the World)
The eye collects and focuses light….
But is filled with fluid…

5. Distal Stimulus (Information in the World)
The eye collects and focuses light….
But is filled with fluid…

6. Distal Stimulus (Information in the World)
3-Dimentional image is reversed and inverted on to a 2-Dimentional Screen

7. Distal Stimulus (Information in the World)
3-Dimentional image is reversed and inverted on to a 2-Dimentional Screen
- Image is necessarily distorted

8. Proximal Stimulus (Information in the Brain)
Fovea
Photoreceptors (Rods & Cones) on retina translate light into nerve impulses…
This translation is necessary because the nerve cells in the brain only respond to other nerve cells (not to light)

9. Proximal Stimulus (Information in the Brain)
Nerves connect retinal image
to the brain…
Along the way, the information is
pooled, edited, and altered…
Visual cortex receives and
interprets the signal

10. Perceptual Experience (Interpretation of Proximal Stimulus)

11. Makes best guess about the world
Perceptual Experience (Interpretation of Proximal Stimulus)
Detective Metaphor
Information in the world is impoverished
Makes best guess about the world

12. Problems With The Computational Model of Perception
Impoverished World?
- What does science say?

13. Problems With The Computational Model of Perception
Impoverished World?
- What does science say?
2. Indirect Perception and Radical Skepticism
- Logically denies access to reality

14. Problems With The Computational Model of Perception
Impoverished World?
- What does science say?
2. Indirect Perception and Radical Skepticism
- Logically denies access to reality
3. Homunculus – Where does it stop?

15. Problems With The Computational Model of Perception
In 1942, J. J. Gibson was tasked by the US Air Force
to select recruits who would be good pilots…
Created a battery of perceptual test based on what was
know about perception at the time…
Tests included balance, eye movements, reaction time,
depth perception, and recognition of airplane shapes…
However….
Tests failed to predict flying ability!!!
Tests ignored the role of perception
in performing goal-directed behaviors

16. Problems With The Computational Model of Perception
The tests Gibson created were based on the computational perspective
and the assumptions embedded within that model of perception
The COMPUTATIONAL perspective does a reasonable job
explaining some aspects of perception, such as…
Behavior-Neutral Properties of the World
(Color, Shape, Sizes, and Depth)
The Model one uses informs the questions they ask and the results that follow…

17. Problems With The Computational Model of Perception
The tests Gibson created were based on the computational perspective
and the assumptions embedded within that model of perception
The COMPUTATIONAL perspective does a reasonable job
explaining some aspects of perception, such as…
Behavior-Neutral Properties of the World
(Color, Shape, Sizes, and Depth)
But struggles to explain perception of
Behavior-Relevant Properties
(like those required to fly an airplane)
The Model one uses informs the questions they ask and the results that follow…

18. Ecological Approach to Perception
Rather than asking “What is perception?”
Gibson asked “What is perception for?”
For Gibson, perception is for
the control of goal-directed behavior
If perception is for the control of behavior,
animals must be able to perceive
opportunities for behavior
Gibson believed that the strategy of reductionism was not the appropriate scale of analysis needed
to understand perception of affordances.
The Model one uses informs the questions they ask and the results that follow…

19. Ecological Approach to Perception
For Gibson, the appropriate scale of analysis was
Perception is the relationship between animal & environment
1. The world is full of informative stimulation patterns…
- Invariant and do not require computation
2. Perception is direct…
- Reflect fit between animal & environment and do not require processing
3. No homunculus but perception includes whole body…
- Perception is active and not passive
The Model one uses informs the questions they ask and the results that follow…

20. Perception is the relationship between animal & environment
Ecological Approach to Perception
Perception is the relationship between animal & environment
1. The world is full of informative stimulation patterns…
- Invariant and do not require computation
The Model one uses informs the questions they ask and the results that follow…

21. Perception is the relationship between animal & environment
Ecological Approach to Perception
Perception is the relationship between animal & environment
1. The world is full of informative stimulation patterns…
- Invariant and do not require computation
The Model one uses informs the questions they ask and the results that follow…

22. Perception is the relationship between animal & environment
Ecological Approach to Perception
Perception is the relationship between animal & environment
1. The world is full of informative stimulation patterns…
- Invariant and do not require computation
2. Perception is direct…
- Reflect fit between animal & environment and
do not require processing
Animals create their niche;
the niche support the animal
World is full of informative stimulation patterns
that support animals;
World is its own best model
The Model one uses informs the questions they ask and the results that follow…

23. Perception is the relationship between animal & environment
Ecological Approach to Perception
Perception is the relationship between animal & environment
1. The world is full of informative stimulation patterns…
- Invariant and do not require computation
2. Perception is direct…
- Reflect fit between animal & environment and
do not require processing
3. No homunculus but perception includes whole body…
- Perception is active and not passive
Animals create
informative
stimulation patterns
The Model one uses informs the questions they ask and the results that follow…

24. Ecological Approach to Perception
The ECOLOGICAL argument versus computational:

25. Wagman, Langley, Farmer-Dougan, 2016
The Question: How do canines perceive reaching affordances?
Performing any behavior requires perceiving whether and how that behavior can be performed (i.e., affordances).
Perception of affordances is action scaled. It reflects the fit between environmental properties and action capabilities.
For example, human perception of maximum reaching distance is longer for long- than for short-armed people but occurs at the same ratio of object-distance-to-arm-length for both groups.

26. We investigated perception of maximum reaching heights by canines.
Wagman, Langley, Farmer-Dougan, 2016
The Question: How do canines perceive reaching affordances?
We investigated perception of maximum reaching heights by canines.
We expected that perceived reaching boundary would occur at a taller height for tall than for short dogs but at the same ratio of shoulder-height-to-treat-height for both groups.

27. 19 canines of various breeds
Wagman, Langley, Farmer-Dougan, 2016
The Question: How do canines perceive reaching affordances?
19 canines of various breeds
6 dogs were pets (2 were deaf)
5 were service dogs in training
8 were shelter dogs

28. Wagman, Langley, Farmer-Dougan, 2016
The Question: How do canines perceive reaching affordances?
We systematically presented treats at various heights to determine the height at which dogs transitioned from reaching with the head to rearing.

29. Wagman, Langley, Farmer-Dougan, 2016
The Question: How do canines perceive reaching affordances?
We systematically presented treats at various heights to determine the height at which dogs transitioned from reaching with the head to rearing.
Tall canines reared at a taller height (M = 92.5 cm, SD = 6.5 cm) than shorter canines (M = 78.3 cm, SD = 6.27 cm)

30. Wagman, Langley, Farmer-Dougan, 2016
The Question: How do canines perceive reaching affordances?
We systematically presented treats at various heights to determine the height at which dogs transitioned from reaching with the head to rearing.
But the average ratio of rearing-height-to- shoulder height did not differ for tall (M = 1.52, SD = 0.03) and short canines (M = 1.52, SD = 0.07).
Tall canines reared at a taller height (M = 92.5 cm, SD = 6.5 cm) than shorter canines (M = 78.3 cm, SD = 6.27 cm)

31. Wagman, Langley, Farmer-Dougan, 2016
The Question: How do canines perceive reaching affordances?
We systematically presented treats at various heights to determine the height at which dogs transitioned from reaching with the head to rearing.

32. Wagman, Langley, Farmer-Dougan, 2016
The Question: How do canines perceive reaching affordances?
We systematically presented treats at various heights to determine the height at which dogs transitioned from reaching with the head to rearing.
Importance:
Dogs rear at a constant ratio of shoulder height-to-treat height.
This ratio appears constant across breeds and dogs of differing sizes.
These data provide critical information for trainers handling dogs in agility, scent work, search and rescue, and other areas where dogs are required to rear up or otherwise manipulate their bodies in the environment.

33. Wagman, Langley, Farmer-Dougan, 2016
The Question: How do canines perceive reaching affordances?
We systematically presented treats at various heights to determine the height at which dogs transitioned from reaching with the head to rearing.
Future Research:
Backpack: We expect that there will be a change in the average ratio of rearing-height-to- shoulder height for the canines.

34. Wagman, Langley, Farmer-Dougan, 2016
The Question: How do canines perceive reaching affordances?
We systematically presented treats at various heights to determine the height at which dogs transitioned from reaching with the head to rearing.
Future Research:
Stress Behavior: We expect that there will be an increase in the frequency and duration of stress behaviors and an increase in response latency at the perceptual boundary.

35. Wagman, Langley, Farmer-Dougan, 2016
The Question: How do canines perceive reaching affordances?
We systematically presented treats at various heights to determine the height at which dogs transitioned from reaching with the head to rearing.
Future Research:
Hystersis: We expect that perceptual boundaries will occur at taller heights when heights are presented in ascending than in descending order.