1. Sensation and Perception
How accurate are our senses?
Selective Attention: Humans block out almost everything that bombards us. We have a unique ability that allows us to focus on what we need to focus on while blocking out everything else.
Our senses take in 11 million bits
of information per second – but we only process about 40 of them.
2 things about Selective Attention
1.) Cocktail party effect
our ability to drown out all but one person’s voice despite all of the other noise around us

2. Sensation
The result of converting physical stimulation into a sensory experience
“What you felt/experienced”
Subjective in nature

3. Stimulus
Any aspect or change in the environment to which an organism responds
Objective in nature
Psychophysics deals/studies the relationship of sensation and stimulus

4. Absolute Threshold
The smallest amount of energy (stimulus) that produces a sensation at least half the time

5. Difference Threshold The just noticeable difference between stimuli
Hearing tests, vision tests

6. Weber’s Law
The stronger the stimulus, the larger the change required for the observer to notice
Examples: baby weight, hair weight, stereo sound, dusk

7. Perception Selective Attention focusing of conscious
awareness on a particular stimulus
What do you see? Circles with white lines, a cube, the little x, peace signs?
Humans have a the unique ability to block out the majority of information that is thrown at us. We can ignore most things while focusing on what we need to focus on.
Our senses are take in 11 million bits of information per second, but we only process about 40.
2 things to think about with Selective Attention
1.) The cocktail party effect
the ability to drown out everything but one person’s voice despite the large amount of noise

8. Change Blindness #2 is Change Blindness
Won’t notice if something changes around you if we’re really focused on something else

9. Perceptual Illusions Which is longer?
Most say they are the same length, but AB is longer than BC

10. Perceptual Organization: Gestalt
Grouping
the perceptual tendency to organize stimuli into coherent groups
Grouping Principles
proximity--group nearby figures together
similarity--group figures that are similar
continuity--perceive continuous patterns
closure--fill in gaps
connectedness--spots, lines, and areas are seen as unit when connected

11. Perceptual Organization: Grouping Principles

12. Perceptual Organization: Closure
Gestalt grouping principles are at work here.

13. Perceptual Organization: Grouping Principles
Gestalt grouping principles are at work here.

14. Perceptual Organization: Grouping Principles
Impossible doghouse

15. Perceptual Organization
Figure and Ground--organization of the visual field into objects (figures) that stand out from their surroundings (ground)

16. Perceptual Organization: Depth Perception
Visual Cliff

17. Perceptual Organization: Depth Perception
Monocular Cues
relative size
smaller image is more distant
interposition
closer object blocks distant object
relative clarity
hazy object seen as more distant
relative brightness
closer objects appear brighter

18. Perceptual Illusions
Look at the girls this way

19. Perceptual Illusions Now look at them again. Why did it change?
There are no right angles in the room which throws off your perception and the clocks are different sizes
Look in your book at page 234 – the St. Louis Arch it is the same distance wide as it is tall.

20. Ames Room
The Ames room is designed so that the monocular depth cues give the illusion that the two people are equally far away

21. Perceptual Organization: Depth Perception
Relative Size

22. Perceptual Organization: Depth Perception
Interposition

23. Perceptual Illusions
Fog can affect our perception. Which one seems further away?

24. Perceptual Illusions
There are more illusions in the book

25. Perceptual Organization: Depth Perception
Monocular Cues (cont.)
relative height
higher objects seen as more distant
relative motion
closer objects seem to move faster
linear perspective
parallel lines converge with distance
texture coarse --> close fine --> distant

26. Perceptual Organization: Depth Perception
Relative Height

27. Perceptual Organization: Depth Perception
Perspective Techniques

28. Perceptual Organization: Depth Perception
Light and Shadow

29. Perceptual Organization

30. Perceptual Interpretation
Perceptual Adaptation
(vision) ability to adjust to an artificially displaced visual field
prism glasses
Perceptual Set
a mental predisposition to perceive one thing and not another

31. Perceptual Set: Schemas
What you see in the picture is influenced by perceptual set

33. Sensory Adaption
Senses have a general ability to adapt to constant levels of stimulation
Examples: light in room, clothes, street noises, trains etc
Senses are most sensitive to changes in environment / stimuli

34. Habituation
Loss of sensation due to unchanging magnitude of stimulation
Examples: glasses, cap, jewelry, etc.

44. Seeing 4-5 faces is average, 6-7, above average, 8-9 very observant, 10-11 extraordinary orbervant.

49. Illusions