What is the difference between sensation and. Perception:

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1 4C signal detection and subliminal messages 1 What is the difference between sensation and perception? Sensation: The process of detecting a stimulus, such as light waves (vision), Perception: The process of integrating, organizing and interpreting sensations. sound waves (hearing), chemical molecules (smell and taste ), heat or pressure (touch). You might want to think of sensation and perception as two ends of a continuum. There is no clear dividing line between sensation and perception. Where sensation ends and perception begins is difficult to determine.

2 4C signal detection and subliminal messages 2 Signal Detection Theory Signal detection theory states that detecting a stimulus [by a person] is not an objective processes (page 178). Detecting a stimulus is a subjective decision involving (1) sensitivity to the stimulus in the presence of distractions from other stimuli (noise) and (2) the criteria used to make judgments from ambiguous information (also see response bias, page 178). When detecting light stimuli, (1) The reality of the light is that it is on or off, and (2) you must decide if it is on or off. Image source: Psychological Science, 4 th edition, (2013), Gazzaniga, Heatherton, and Halpern

3 4C signal detection and subliminal messages 3 Signal Detection: Intensity of the Stimulus Higher Intensity Light presented Light not presented Your response yes, yes yes, yes Your response no, no no, no, no, no, no, no, no, no Lower Intensity Light presented Your response yes, yes Your response no, no, no, no Light not presented yes, yes no, no, no, no, no, no

4 4C signal detection and subliminal messages 4 Signal Detection: Response bias Liberal: You are more likely to say yes. Your standards are more lax. Light presented Your response yes, yes Your response no, no Light not presented yes, yes no, no There is a higher risk of s (false alarm) where you will respond when there is no actual event (light) Conservative: You are more likely to say no. Your standards are high. Light presented Your response Your response no, no, no, no, no, no, no, no Light not presented yes, yes no, no, no, no, no, no, no, no There is a higher risk of ing something that really is there where you won t respond to something that actually is there.

5 4C signal detection and subliminal messages 5 Signal Detection: Response bias Liberal: If people haven t paid their taxes, was it an honest mistake (Ming) and be forgiving? The person made an honest mistake Be forgiving Come down hard on them The person was trying to cheat on their taxes There is a higher risk of s (false alarm) where you will respond when there is no actual event (light) Conservative: If people haven t paid their taxes, did they try to cheat the system (Boris) and need come down hard on them? The person made an honest mistake Be forgiving Come down hard on them The person was trying to cheat on their taxes There is a higher risk of ing something that really is there where you won t respond to something that actually is there.

6 4C signal detection and subliminal messages 6 Signal Detection: Response bias Liberal: You are more likely to accept new information, regardless of whether it is accurate or not. New information is true Believe it Dis it New information is false There is a higher risk of s (false alarm) where you believe lots of things that are not true. Conservative: You are less likely to accept new information, regardless if it is true or not. New information is true New information is false Believe it Dis it There is a higher risk of ing something that really true, but don t believe it. Critical thinking can help you evaluate incoming information. However, we are prone to use biased thinking (see Chapter 1 and Psy 202).

7 4C signal detection and subliminal messages 7 Signal Detection: Response bias Signal Detection Theory: An observation that the response to a stimulus depends both on Intensity of the stimulus on a person s response bias. Is the Light on? Image source: Psychology (2009), Schacter et. al

8 4C signal detection and subliminal messages 8 In the real world, we have to make judgments under uncertainty such as school closures due to bad weather, surgery for cancer, detection of enemy aircraft, assessment of bomb threats, lie detection, etc.

9 4C signal detection and subliminal messages 9 When distributing financial aid, there are some people who may need it, and some who may not really need it. Award financial aid Reject financial aid Sam needs financial aid Chris doesn t need financial aid Should you perform a medical procedure for breast cancer? Perform surgery Not perform surgery you have breast cancer* you have don t have breast cancer* * there is uncertainty in detection of cancer

10 4C signal detection and subliminal messages 10 A decision at 5:00 am needs to be made: Should you close the school? Close school Keep school open Weather will get worse Weather will get better Is the bomb threat real? Evacuate Not evacuate There is a bomb There is NO bomb

11 4C signal detection and subliminal messages 11 Should you attack an unknown aircraft? Shoot aircraft down Hold your fire Enemy aircraft Friendly aircraft Is the person lying about stealing $100 when the lie detector is spiking? I think they are lying I think they are telling the truth They lied about stealing They are telling the truth about stealing What are other decisions that can be looked at with the signal detection framework?

12 4C signal detection and subliminal messages 12 How much product should I order? I order a lot of product I order a small amount of product The product will sell The product won t sell As a police officer, do I shoot that person? I shoot I hold my fire The person is a criminal The person is not a criminal is the person dangerous? Is the item a weapon?

13 4C signal detection and subliminal messages 13 Sensory Processes There are some basic concepts that psychologists use when talking about the sensitivity of the senses (pages Sensory adaptation: A decrease in sensitivity to a constant level of stimulation (page 178). Sensory adaptation: The decline in sensitivity of the basic senses to a constant stimulus. Therefore, a stronger stimulus is required to activate the senses (another definition). Smell: Touch Hearing:

14 4C signal detection and subliminal messages 14 Sensory Adaptation How does sensory adaptation help us understand the world around us? Image source: unknown

15 4C signal detection and subliminal messages 15 Sensory Adaptation How does sensory adaptation help us understand the world around us? Image source: unknown

16 4C signal detection and subliminal messages 16 Why is understanding sensory adaptation important in what cases would sensory adaptation be bad? in what cases would sensory adaptation be good?