1. Sensation and Perception

7. Sensation vs. Perception
The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment
Perception
The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

8. Bottom-up Processing
Analysis of the stimulus begins with the sense receptors and works up to the level of the brain and mind. (simple to high)
Letter “A” is really a black blotch broken down into features by the brain that we perceive as an “A.”

10. THE CHT Top-Down Processing
Information processing guided by higher-level mental processes as we construct perceptions, drawing on our experience and expectations. (analytical)
THE CHT

11. Example of Top-Down Processing
Aoccdrnig to rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a total mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.

12. Making sense of Complexity
Top-down and Bottom-Up both work together to help us sort out complex issues

13. Selective Attention
Focusing conscious awareness on a particular stimulus to the exclusion of others
The ability to focus on one stimulus at a time
Allows a person to function in a world filled with many stimuli

14. PSA
fMRI scans reveal that brain activity in areas vital to driving decreases by 37% when a driver is attending to a conversation

16. Inattentional Blindness
Failing to see visible objects when our attention is directed elsewhere

17. Change Blindness
Failing to notice changes in the environment

18. Transduction
Transforming of stimulus energies into neural impulses our brain can interpret

19. Absolute Threshold
The minimum amount of a stimulation needed to detect a particular stimulus
Amount of a stimulus that a person can detect 50% of the time

20. Detection Absolute Threshold Intensity No No No Yes Yes Detected
Observer’s Response
Detected
Tell when you (the observer) detect the light.

21. Absolute Thresholds for Humans
Vision: Candle flame seen at 30 miles on a clear, dark night
Hearing: Tick of a watch under quiet conditions at 20 feet
Touch: A bee's wing falling on your cheek from 1 centimeter above
Smell: 1 Drop of perfume diffused into a three-room apartment
Taste: 1 Teaspoon of sugar in 2 gallons of water

22. Difference Threshold
Minimum difference between two stimuli required for detection 50% of the time, also called just noticeable difference (JND)
Difference
Threshold No No
Yes
Observer’s Response
Tell when you (observer) detect a difference in the light.

24. Weber’s Law
The size of the JND is proportional to the intensity of the stimulus
If the stimulus intensity is high, the JND will be large (or it will take a bigger increase to be noticed)
If the stimulus intensity is low, the JND will be smaller (or it will take less of an increase to be noticed)

25. Subliminal Threshold
When stimuli are below one’s absolute threshold for our conscious awareness
In other words…for most people these items are not detected

26. “Subliminal” messages in advertisements

28. More subtle subliminal messages…….

30. Signal Detection Theory
Assumes there is no absolute threshold
Depends on an individuals experience, expectations, motivation, and alertness

31. Sensory Thresholds Sensory adaptation
Diminished sensitivity as a consequence of constant stimulation
An adjustment of the senses to the level of stimulation they are receiving

32. What do these letters spell?F O L K

33. What do these letters spell?C R O A K

34. What do these letters spell?K

35. What do we call the white of an egg?

36. Influences on Perception

37. Perceptual Set

38. Perceptual Set
A mental predisposition to perceive something one way and not another
Example of top-down processing
Influence of the “power of suggestion” (subliminal perception)
Guided by schemas: concepts or mental frameworks that organize and interpret information (develop from experience)

40. Context Effect
Different stimulus may trigger radically different perceptions

41. The “little guy” shown here is actually 6’9 who would tower over most of us
The other guy is the world’s tallest basketball player at that time, 7’9