Aim How do sensory adaptation and habituation differ

Aim: How do sensory adaptation and habituation differ? What is a threshold? Do Now: 1. Put a pencil behind your ear. 2. What is absolute threshold? Give an example. Homework: Study for test next week TUESDAY. Work on study guide.

Do you still fee the pencil on your ear or did you become less sensitive to it? There are TWO ways we become LESS SENSTITIVE to stimuli…. Adaptation Habituation

Sensory Adaptation • a change in the responsiveness of the sensory stem based on the average level of surrounding stimulation, become less responsive to an unchanging stimuli ( it takes time ) – blind right after you turn off lights – freezing when first in pool • Fatigue effect - receptors become fatigued and fire less frequently - “hard to go back” • This occurs automatically – you have no control over it

George Stratton 1897 • Wondered what would happen if we found ourselves in an upside down, wrong way visual world. • Designed Glasses and wore them. • What do you think happened? After a week of wearing them? When he removed them? https: //www. youtube. com/watch? v=koh. Up. Qw. Zt 8&app=desktop

Perceptual Adaptation • The brain adapts to perception it receives. • Vision adjusted to distorted visual sensation and takes time to readjust as well

Movement Afterimage • • Stare at spiral. Then look at your hand. What happened? Why? Relate to feature detectors, sensory adaptation and fatigue effect. • http: //www. sandlotscience. com/Aftereffects/Andrus_Spiral. htm

Movement Afterimage Explained • Caused by the adaptation of motion-specific detectors being viewed. (feature detectors) • Detectors gradually adapt and become less sensitive. (adaptation) • When the stimulus is removed, the motion detectors for the opposite direction produce a stronger signal for a few seconds (opponent process effect).

Feature Detectors • feature detectors – neurons in the brain’s visual system that respond to particular features of a stimulus • Specialized nerve cells in brain respond to specific features of visual stimuli (lines, edge, movement, angle). Discovered by Hubel & Weisel http: //www. youtube. com/watch? v=IOHayh 06 LJ 4&safety_mode=t rue&persist_safety_mode=1&safe=active

The Visual Cortex: David Hubel and Torsten Wiesel (1963) • won Nobel Prize for research on feature detectors (in cats) – recorded activity of a single neuron in a cat while it looked at patterns that varied in size, shape, color , and movement – found that the visual cortex has neurons that are individually sensitive to different types of lines and angles – Noted that when deprived of certain types of visual stimulation early one, kittens lost the ability to perceive these patterns • Suggests there might be a critical period in visual development and that the brain requires stimulation it its efforts to delegate its resources to different perceptual tasks brain “learns” to perceive through experience. http: //www. youtube. com/watch? v=IOHayh 06 LJ 4&safety_mode=t rue&persist_safety_mode=1&safe=active

Aim: To review for exam Do Now: Think of an example of sensory adaptation for each sense. Homework: Study for test tomorrow. Study Guide Due and Children’s Book Due

Think of an example of Sensory Adaptation in the following senses. • • • Smell Taste Touch Vision Hearing Vestibular

Demonstration – Monkey Business Illusion TASK: Count # of times white shirts pass ball. • ORIGINAL TEST https: //www. youtube. com/watch? v=IGQmdo. K_Zf

What is Habituation?

Perceiving Sensory Stimuli: Attention • attention – the process of focusing awareness on a narrowed aspect of the environment • Cocktail party effect/ selective attention/ habituation • – the process of focusing on a specific aspect of experience while ignoring others, where you are less responsive to some stimuli. WHY? ? ? • To protect you from too much sensations you block out certain sights, sounds etc. , but you have the ability to go back to the sound/ sight etc. (attention can shift back and forth. )

What influences attention? • shiftable – Monitoring many things at once • novel stimuli – Novel – Different – Unusual • size, color, movement • emotional stimuli (specific words, etc. ) – emotion-induced blindness – when we encounter an emotionally charged stimulus, we often fail to recognize a stimulus that is presented immediately after • inattentional blindness – failure to detect unexpected events when our attention is engaged by tasks http: //www. youtube. com/watch? v=ub. NF 9 QNEQLA&safety_

Habituation • A Person can shift attention away from things to block out stimuli • We can ignore unchanging stimuli and we a drawn to novel stimuli • This is a more conscious process • Ie loud noises over time you “block out”

Stroop Effect • Illustrates the way that automatically reading a color name can make it difficult to name the color in which the word is printed • failure of selective attention/ dividing attention is difficult • We can only pick and choose one thing to focus on

Review Activities

How is selective attention affected by the following… • • Color Intensity of Stimulus Changes in Stimulus Magnitude of Stimulus Repetition Meaning Novelty

Give an example of where attention has affected your perception?

Herman Herring Illusion

Herman Herring Illusion • The retina is partially composed of many small nerves, which function as receptors of light. These receptors are arranged in rows on the inside of your retina • It was discovered that if you illuminate a single receptor (A) you will get a large response; however, when you add illumination to A‘ • Thus the illumination of receptors "inhibits" of firing of neighboring receptors. This effect is called lateral inhibition.

• In the Hermann grid, there is light coming from the four sides of the intersection, but from only two sides of a band going away from the intersection. The region viewing the intersection is more inhibited than the region of the band going away. Thus the intersection appears darker than the other section. You see dark spots at the intersections of the white bands, but not at the points away from the intersections.