PSYC 310 1st Edition Lecture 4Outline of Last Lecture I. Language & Brain ImagingII. Event Related PotentialIII. Representation in the BrainOutline of Current Lecture I. Types of Perception & DefinitionsII. Direct Perception TheoriesIII. Helmholtz’s Theory of Unconscious Inference (~1860)IV. Perceptual OrganizationCurrent LectureI. Types of Perception & Definitionsa. The Complexity of Perceptioni. Perception is…1. The process of recognizing, organizing and interpreting information from senses2. Not an exact copy of “the world”3. Influenced by past experiences and expectationsii. Bottom-up Processing1. Perception may start with the senses2. Incoming raw data3. Energy registering on receptorsiii. Top-down processing1. Perception may start with the brain2. Person’s knowledge, experience, expectationsiv. Definitions:These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1. Sensation – absorbing raw energy (light waves, sound waves) through our sensory organs2. Transduction – conversion of this energy to neural signals3. Attention – concentration of mental energy to process incoming information4. Perception – selecting, organizing, and interpreting these signalsII. Direct Perception Theoriesa. Direct Perception Theoriesi. Bottom-up processingii. Perception comes from stimuli in the environmentiii. Parts are identified and put together, and then recognition occursb. Bottom-up Processing Physiologicali. Overview: Sensation and Perception1. Energy contains information about the world (usually incomplete, full of noise, and distorted)2. Anatomical accessory structure modifies energy3. Receptor transduces energy into a neural response4. Sensory nerve transmits the coded activity to the central nervous system5. Thalamus processes and relays the neural responsea. Relayed to specialized areas of the cortex6. Perception of the world is created by activity in cortices7. Feature Detectors – Neurons that respond most efficiently to specific visual orientations, etc. (One of first steps of brain’s response to objects)ii. Bottom-up Processing: Behavioral1. Recognition-by-components theory (RBC; Biederman, 1978)a. We perceive objects by perceiving elementary featuresb. Geons: three-dimensional shapesc. An object is made of a unique configuration of a set of geonsd. Objects are recognized when enough information is available to identify object’s characteristic geons.2. Geonsa. Discriminability: geons can be distinguished from othergeons from almost all viewpointsb. Resistance to visual noise: geons can be perceived in “noisy” conditionsc. Distinct: 36 different geons have been identifiediii. Constructive Perception Theories1. Top-down processing – involves making inferences based on context, guessing from experience and basing one perception on another (occurs quickly and automatically)a. Using Knowledgei. Language:1. Speech segmentation: top-down processing2. Our knowledge of English allows us to find breaks between words3. When perceiving an unknown language, may sound continuous2. People actively construct perceptions using information based on expectationsa. Expectations can be due to current environment and/or knowledge from past experiencesiv. Perceiving Size: Taking Distance into Account1. Perceived size is a function of both bottom-up and top-down processing2. Bottom-up processinga. The size of the image on the retina3. Top-down Processinga. The perceived distance of the objectb. The size of the object relative to other objects in the environmentIII. Helmholtz’s Theory of Unconscious Inference (~1860)a. Top-down Theoryb. Some of our perceptions are the result of unconscious assumptions we make about the environmenti. We use our knowledge to inform our perceptionsc. We infer much of what we know about the worldd. Likelihood principle: we perceive the world in the way that is “most likely” based on our past experiencesIV. Perceptual Organizationa. “Old” view – structuralismi. Perception involves adding up sensationsb. “New” view – Gestalt Psychologistsi. The mind groups patterns according to laws of perceptual organizationii. Introduced by Wertheimer, Kohler &Koffkac. Gestalt Laws of Perceptual Organizationi. Law of good continuation1. Lines tend to be seen as following the smoothest pathii. Law of Good Figure (simplicity or prägnanz)1. Every stimulus pattern is seen so the resulting structure is as simple as possibleiii. Law of Similarity1. Similar things appear grouped togetheriv. Law of Familiarity1. Things are more likely to form groups if the groups appear more familiar or meaningfulv. Law of Proximity1. Things near each other appear grouped togethervi. Law of Common Fate1. Things moving in the same direction appear to be grouped togethervii. Gestalt Laws often provide accurate information about properties of the environment1. Reflect experience2. Used unconsciously3. Occasionally misleadingviii. Gestalt Laws are