I. Genetic influence vs. environmental influenceI. II. Ames’ RoomII. Size Constancya. Retinal ImageVariation in brain structure among people because of genomesTestosterone: higher levels of testosterone associated with higher levels of aggressiveness. Drugs that activate serontoninergic neurons/synapses can greatly reduce aggressive acts in people with an aggressive history- Violent has declined: world-wide battle deaths have decreasedSensory processes = bottom-up. Perceptual process = top-down- At least 30% of the brain is involved in visual processes- Many basic processes of sensing and perceiving are fast, automatic, and pre-conscious- People tend to have a dominant eye- Perceived properties of the visual world tend to remain constant even though the proximal stimulus (retinal image in vision) constantly changes.Ex: watching a door open. Learned that doors are rectangular throughout our lives. Doors don’t change shape, I’ve learned this throughout my life. Non-conscious shape constancy. The shape of the retinal image of an object differs according to object motion and viewpoint, but we don’t perceive the object’s shape as changing.- Size constancy: size of the retinal image changes as distance from the object to viewer increases, but you don’t see the object as getting taller, we look at it as a object in the distance.There are other cues in the visual field that provide distance information – “same object at different distances”- Distance cues: occlusion, linear perspective, texture density, plus top-down influences (existing knowledge, context, expectations). Binocular vision can also supply cues to distance- Distance can be misleading and lead to perceptual illusions: differences in or changes in the perceived size of objects, caused by misleading distance cues.Why do illusions occur?  If two objects that are at different distances from the observer produce the same-sized retinal image, the more distant object must be larger. The perceptual system of the brain will arrive at this conclusion even when the objects are not at different distances but seem to be.- Looking at two objects: what are their apparent distances? What about the retinal image size?- Illusion: The perceptual system interprets the differences in retinal image size as being due to different distances, not differences in actual sizes• The brain’s perceptual system says: “These two people seem about the same distance away from me, but A has a much smaller retinal image than B.”- Ames’ room: example of perceived distancesTop-Down: the effect of existing knowledge and past experience and expectations (schema) on the perception of new stimulus events.Schema: a “mental framework” for interpreting and assimilating new information.Bottom-up: analysis of the basic properties of incoming sensory information (sense organs, thalamus, early cortical processing).Perception is most often the product of both processes.Top-down usually facilitates sensing and perceiving. But top-down can impair perception as well.Context can bias perception, sometimes to your advantage and sometimes not. “Distal stimulus” can be the same but the perceived stimulus is quite different.Ex: number 15 and word “is” when written by hand- Mairzey Doats: when heard without lyrics, the song sounds like sounds, but with lyrics you can understand what the song is saying. Printed lyrics provide an interpretive context (schema) for the song lyrics. Aids perception of an ambiguous stimulus.PSYC 100 1st Edition Lecture 10 Outline of Last Lecture I. Genetic influence vs. environmental influence Outline of Current LectureI. II. Ames’ RoomII. Size Constancya. Retinal ImageCurrent Lecture Variation in brain structure among people because of genomes- Testosterone: higher levels of testosterone associated with higher levels of aggressiveness. Drugs that activate serontoninergic neurons/synapses can greatly reduce aggressive acts in people with an aggressive history - Violent has declined: world-wide battle deaths have decreased Sensory processes = bottom-up. Perceptual process = top-down - At least 30% of the brain is involved in visual processes - Many basic processes of sensing and perceiving are fast, automatic, and pre-conscious  - People tend to have a dominant eye - Perceived properties of the visual world tend to remain constant even though the proximal stimulus (retinal image in vision) constantly changes. - Ex: watching a door open. Learned that doors are rectangular throughout our lives. Doors don’t change shape, I’ve learned this throughout my life. Non-conscious shape constancy. The shape of the retinal image of an object differs according to object motion and viewpoint, but we don’t perceive the object’s shape as changing.  - Size constancy: size of the retinal image changes as distance from the object to viewer increases, but you don’t see the object as getting taller, we look at it as a object in the distance.- There are other cues in the visual field that provide distance information – “sameobject at different distances” - Distance cues: occlusion, linear perspective, texture density, plus top-down influences (existing knowledge, context, expectations). Binocular vision can also supply cues to distance - Distance can be misleading and lead to perceptual illusions: differences in or changes inthe perceived size of objects, caused by misleading distance cues.- Why do illusions occur?  If two objects that are at different distances from the observer produce the same-sized retinal image, the more distant object must be larger. The perceptual system of the brain will arrive at this conclusion even when the objects are not at different distances but seem to be. - Looking at two objects: what are their apparent distances? What about the retinal image size?  - Illusion: The perceptual system interprets the differences in retinal image size as being due to different distances, not differences in actual sizes • The brain’s perceptual system says: “These two people seem about the same distance away from me, but A has a much smaller retinal image than B.”  - Ames’ room: example of perceived distances Top-Down: the effect of existing knowledge and past experience and expectations (schema) on the perception of new stimulus events.  Schema: a “mental framework” for interpreting and assimilating new information.