Psychology Lecture Notes PDF

Lecture 5: Sensation & Perception: ================================== 1. **Sensation vs. Perception**: a. **Sensation** is the process by which sensory receptors and the nervous system detect stimuli from the environment. b. **Perception** is how the brain organizes and interpr...

Lecture 5: Sensation & Perception: ================================== 1. **Sensation vs. Perception**: a. **Sensation** is the process by which sensory receptors and the nervous system detect stimuli from the environment. b. **Perception** is how the brain organizes and interprets this sensory information to make it meaningful, allowing us to recognize objects, events, and patterns. c. Example: Sensation occurs when light hits the retina in the eye, while perception happens when the brain interprets this light as an image or object. 2. **Sensory Receptors & Transduction**: d. **Sensory receptors** are specialized neurons that detect external stimuli. e. **Sensory transduction** is the process of converting physical stimuli (like light or sound) into chemical energy (neuronal signals). This is the first step in sensation. f. Example: In vision, light waves are transduced into neural signals that the brain interprets as visual images. 3. **The Visual System**: g. **Light** is a form of electromagnetic radiation, with wavelengths between 380 nm and 760 nm being visible to the human eye. h. **The human eye** has several key parts: i. **Cornea**: Transparent outer layer where light enters. ii. **Iris**: Muscular ring that controls the size of the **pupil** (the hole where light enters). iii. **Lens**: Focuses light onto the retina. iv. **Retina**: Contains the **photoreceptors** (rods and cones) responsible for detecting light. v. **Optic nerve**: Transmits signals from the retina to the brain. 4. **Photoreceptors: Rods vs. Cones**: i. **Cones**: vi. Responsible for detailed, color vision and work best in daylight. vii. Concentrated in the **fovea**, the area of the retina with the highest visual acuity. j. **Rods**: viii. More numerous than cones and responsible for vision in low-light conditions. ix. Located primarily in the peripheral parts of the retina and do not detect color. k. Example: In dim light, we rely more on rods, which is why colors are harder to see at night. 5. **Depth Perception**: l. **Binocular depth cues**: x. Relies on the slightly different views from both eyes (retinal disparity) and the **convergence** of the eyes when focusing on objects up close. m. **Monocular depth cues**: xi. Useful for objects at greater distances and include cues like **relative size** (closer objects appear larger) and **linear perspective** (parallel lines appear to converge as they get farther away). xii. Example: The **Ponzo illusion** is a classic example of how linear perspective can trick our depth perception. 6. **Gestalt Principles of Perception**: n. **Gestalt psychology** studies how we perceive whole objects rather than just a collection of parts. o. Key principles: xiii. **Closure**: We fill in gaps to create a complete object. xiv. **Similarity**: Objects that are similar are grouped together. xv. **Proximity**: Objects that are near each other are perceived as related. xvi. **Good continuation**: We perceive smooth, continuous lines rather than disjointed ones. 7. **Perceptual Constancies**: p. **Size constancy**: We perceive objects as the same size even if their image on the retina becomes smaller as they move away. q. **Shape constancy**: We perceive objects as maintaining the same shape even when viewed from different angles. r. **Color constancy**: Our brain adjusts for changes in lighting so that we perceive objects as maintaining their color. Lecture 6: Learning & Memory: ============================= 1. **Learning vs. Memory**: a. **Learning** is a lasting change in behavior resulting from experience. b. **Memory** refers to the process of encoding, storing, and retrieving information in the brain as a result of learning. c. Learning involves behavioral change, while memory allows us to retain and use learned information. 2. **Classical Conditioning (Ivan Pavlov)**: d. **Classical conditioning** is a type of learning where a neutral stimulus becomes associated with an unconditioned stimulus, eventually eliciting a conditioned response. e. Key terms: i. **Unconditioned stimulus (UCS)**: A stimulus that naturally produces a response (e.g., food). ii. **Unconditioned response (UCR)**: The natural response to the UCS (e.g., salivation). iii. **Conditioned stimulus (CS)**: Previously neutral stimulus that, after being paired with the UCS, elicits the conditioned response (e.g., a bell). iv. **Conditioned response (CR)**: The learned response to the CS (e.g., salivation at the sound of the bell). f. Example: Pavlov's dogs learned to salivate at the sound of a bell when it was repeatedly paired with food. 3. **Operant Conditioning (B.F. Skinner)**: g. **Operant conditioning** involves learning through rewards and punishments, where behaviors are influenced by their consequences. h. **Reinforcement** (increases behavior): v. **Positive reinforcement**: Adding something pleasant (e.g., a treat). vi. **Negative reinforcement**: Removing something unpleasant (e.g., ending a chore). i. **Punishment** (decreases behavior): vii. **Positive punishment**: Adding something unpleasant (e.g., scolding). viii. **Negative punishment**: Removing something pleasant (e.g., taking away TV privileges). j. **Reinforcement schedules**: ix. **Continuous reinforcement**: Behavior is reinforced every time. x. **Intermittent reinforcement**: Reinforcement is given at varying intervals or ratios, making behavior more resistant to extinction. 4. **Memory Types**: k. **Explicit memory**: xi. **Episodic memory**: Memory of personal experiences. xii. **Semantic memory**: Facts and general knowledge. l. **Implicit memory**: xiii. **Procedural memory**: Skills and tasks (e.g., riding a bike). xiv. **Associative memory**: Classical conditioning responses. m. **H.M.'s case**: After surgery to treat epilepsy, H.M. lost the ability to form new explicit memories, highlighting the role of the hippocampus in memory consolidation. 5. **Forgetting and Interference**: n. **Forgetting curve** (Ebbinghaus): We forget most information rapidly after learning, but what remains tends to be retained over time. o. **Proactive interference**: Old memories interfere with new memories (e.g., learning a new language after mastering another). p. **Retroactive interference**: New memories interfere with recalling old memories (e.g., difficulty remembering an old address after moving). q. **Flashbulb memories**: Strong memories formed under intense emotional experiences, though they may not always be accurate. Lecture 5: Sensation & Perception (Additional Notes): ===================================================== - **Light as a Stimulus**: - Light is part of the electromagnetic spectrum (380-760 nm). - Wavelength determines color (short = blue/violet, long = red). - **The Auditory System**: - Sound waves are created by vibrating objects. - **Frequency (Hz)** determines pitch, **amplitude (dB)** determines loudness. - Structure of the ear: - **Outer** **ear** (Pinna): Collects sound waves. - **Middle ear**: Tympanic membrane (eardrum) & ossicles (malleus, incus, stapes). - **Inner ear**: Cochlea, where sound is transduced into neural signals by hair cells. - **Transduction of Sound**: - Sound vibrations move the **basilar membrane**, shearing hair cells, which convert it to neural signals (auditory nerve). - **Somatosensory System**: - Detects sensations: touch, pressure, vibration, pain, temperature. - Receptors: pressure-sensitive, thermoreceptors, nociceptors (pain). - **The Homunculus & Somatosensory Cortex**: - Sensory input is mapped in the brain; body parts with more sensory input are represented larger (e.g., hands, lips). - **Perception & Psychophysics**: - **Psychophysics**: Study of stimulus-perception relationship. - **Absolute threshold**: Minimum stimulus intensity detectable 50% of the time. - **Subliminal perception**: Processing stimuli below conscious detection. - **The Gestalt School & Grouping Principles**: - Gestalt psychology: Perception of whole objects, not just parts. - **Grouping principles**: Similarity, proximity, continuity, closure. Lecture 6: Learning & Memory (Additional Notes): ================================================ - **Real-World Classical Conditioning**: - Explains preferences, aversions, emotional reactions (e.g., food poisoning leading to aversion). - **Extinction in Classical Conditioning**: - **Extinction**: CS no longer paired with UCS, leading to CR disappearance; spontaneous recovery may occur. - **Operant Conditioning: Skinner's Reinforcement Schedules**: - **Fixed ratio**: Reward after a set number of responses. - **Variable ratio**: Reward after unpredictable number (e.g., gambling). - **Fixed interval**: Reward after set time (e.g., paycheck every 2 weeks). - **Variable interval**: Reward after unpredictable time (e.g., checking email). - **Cognitive Learning (Edward Tolman)**: - **Latent learning**: Learning occurs without immediate reinforcement; cognitive maps (e.g., rats navigating a maze). - **Memory Encoding, Storage, and Retrieval**: - **Encoding**: Converting input to memory. - **Storage**: Retaining information. - **Retrieval**: Accessing stored information. Memory model compared to a computer (input, processing, storage, retrieval). - **Short-Term vs. Long-Term Memory**: - **Short-term memory**: Temporary, limited capacity (7±2 items). - **Long-term memory**: Stable, lasting years/lifetime; consolidated in the hippocampus. - **The Case of H.M. & Memory Systems**: - H.M.'s case showed the hippocampus is crucial for forming long-term **explicit memories** but not needed for **implicit memories**. - H.M. retained short-term memory but couldn't form new episodic or semantic memories. - **Forgetting and Memory Interference**: - **Proactive interference**: Old memories disrupt new learning. - **Retroactive interference**: New information disrupts old memories. - **Context-dependent memory**: Better recall when context matches the learning environment. - **Eyewitness Memory & Misinformation Effect**: - Eyewitness testimony is unreliable; memory can be altered by misleading information. - **Elizabeth Loftus**: Leading questions and external cues can change memory recall.