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Sensation and Perception. Sensation: your window to the world Perception: interpreting what comes in your window. Sensation. Sensation – process of detecting a stimulus through sensory receptors and the nervous system.
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Sensation and Perception Sensation: your window to the world Perception: interpreting what comes in your window.
Sensation • Sensation – process of detecting a stimulus through sensory receptors and the nervous system. • Process of sensing our environment through taste, sight, sound, touch and smell • Example: • Hearing Mrs. Joseph speak, the sound waves travel to the ears. The hair on the cells in the cochlea help transmit the information to the brain • Prosopagnosia – face blindness • All sensation, no perception
Perception • Perception – process by which we select, organize, and interpret sensory information to recognize meaningful objects and events • Based on our prior experiences and expectations • Example: • Seeing letters on a page and interpreting them as our favorite passage in a novel
Bottoms-up Processing • Bottoms Up Processing (AKA - Feature analysis) • Begins with the sensory receptors and works its way up to the brain • Use the features of the object itself to process the information • Examples: • seeing the individual fruits in this picture • Hearing a voice speak about AP Psych
Top Down Processing • Top Down Processing - Processing information from the senses with higher level mental processes using our experiences and expectations • Using your background knowledge to fill in the gaps • Examples: • Seeing the face in the picture made up of fruit • I _ope yo_ get an 5 on t_ _ A _e_am • Negative expectations about the pain of childbirth can increase pain during the birthing process
Find the following hidden items: • Scissors • Banana • Screwdriver • Horn • Heart • fish • boat • Shoe • needle
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Selective Attention • Selective Attention - Ability to focus our conscious awareness on a particular stimulus • Example: Cell phone usage while driving a car
The Stroop Effect • Stroop Effect –the difficulty attending to the color because of the interference with the meaning of the word
Cocktail-party phenomenon • cocktail party effect - ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations. • Form of selective attention. • Example: • You are at the football game and are cheering for the Comets when you hear Ms. Short call your name
Create your own examplesPick two that you are having the most difficulty with and make your partner come up with a new example • Sensation • Perception • Bottoms-up processing • Tops-down processing • Selective Attention • Stroop Effect • Cocktail Party effect No stinky examples!
Selective Inattention • Change Blindness/Inattentional Blindness - Falling to notice changes in the environment • Example: Eating your lunch in the cafeteria, when your friend switches your sandwich and you don’t notice • Choice Blindness - failure to notice a switch in a choice that is made • Example: Participants asked to pick between two photographed faces, when photographs are switched… • Change deafness – failure to notice a change in voices that are speaking • Example: Listening to Mrs. Joseph speak, failure to notice that Mrs. Harvey is now speaking
Pop Out Effect • Pop out – stimuli we don’t chose to attend to but they draw our eyes and demand our attention • Example: Picture on the left
Psychophysics • Psychophysics - Study of howphysical stimuli are translated into psychological experience. • Psychologists use thresholds to measure these events • Example: Tracking a person’s eye movements jumping every .33 of a second
Thresholds • Threshold – the point at which sensory information is strong enough to be noticed • Absolute threshold – minimum stimulation needed to detect a stimulus (light, sound, pressure, taste or order) 50% of the time • Examples:
Signal Detection Theory • Signal Detection Theory -Predicts how and when we detect a signal amid background noise • Assumes no absolute threshold • Detection depends partly on a person’s experience, expectations , motivation and alertness…people respond differently to same stimuli • Example: Enemy submarine, • Waiting for the Pizza man to come at a busy party
Subliminal Stimulation • Subliminal– below one’s absolute threshold for conscious awareness • Example: • Listening to tapes in your sleep to get you to lose weight • Priming– increased sensitivity to certain stimuli due to prior experience outside conscious awareness • Example: Seeing a picture of a mouse before viewing the picture on the left
100 75 Percentage of correct detections 50 Subliminal stimuli 25 0 Low Medium Absolute threshold Intensity of stimulus Do Subliminal Messages work? • Based on studies, some people do respond to stimuli below the absolute threshold, under some circumstances. • People behave differently at different threshold levels • Priming can briefly influence preferences or perceptions • Complex behaviors are NOT influenced by subliminal messages • Some people are more suggestible than others • Placebo effect
Think Pair Share • What is the difference between absolute threshold and signal detection theory? • You are conducting an experiment with participants who are listening to music that is gradually increased in volume. Describe a hit, miss, correct rejection, & false alarm for this scenario • According to signal detection theory, will the participant always raise their hand at the same volume level if the experiment is repeated? • What are priming and subliminal messaging?
Difference Threshold Difference Threshold (AKA Just Noticeable Difference) – the amount a change needed in a stimulus (stronger or weaker) for us to recognize the change has occurred • the greater the intensity (ex., weight) of a stimulus, the greater the change needed to produce a noticeable change. • Example: • Some people are better at detecting slight variations in the taste of pop
Weber’s Law • Weber’s Law (Related to JND) - For people to really perceive a difference, the stimuli must differ by a constant "proportion" not a constant "amount". • Proportion varies depending on the stimulus
Weber’s Law • JND • Pitch = .003 ( if someone sings a little off key, we will be able to tell) • Loudness = .10 • Saltiness = .20 • Light = .08 • Example: • JND for a 10oz weight = 1 oz. To notice a 50 oz weight would be 5oz • JND for a 10 decibel sound = .10 decibels . To notice a sound of 30 decibels would be _______?
Sensory Adaptation • Sensory Adaption - Diminished sensitivity as a consequence of constant stimulation • Example: Jumping into a cold swimming pool, doesn’t feel cold after a while Your eyes when you turn off the lights Do you feel your underwear all day?
