Perception
Perception is the process of organizing and interpreting sensory information to give it meaning. While sensation is about detecting stimuli, perception is about making sense of what we detect.
Bottom-Up Processing
Analysis that begins with sensory receptors and works UP to brain's integration of sensory information.
Data-driven: "What am I seeing?"
Top-Down Processing
Information processing guided by higher-level mental processes—using experience and expectations.
Concept-driven: "What do I expect to see?"
"The whole is greater than the sum of its parts."
| Principle | Description | Example |
|---|---|---|
| Figure-Ground | We organize perception into objects (figures) that stand out from surroundings (ground) | Rubin's vase/faces illusion |
| Proximity | We group nearby objects together | ○○ ○○ ○○ seen as 3 pairs |
| Similarity | We group similar objects together | ●●○○●●○○ seen as alternating pairs |
| Continuity | We perceive smooth, continuous patterns | Crossing lines seen as two lines, not four |
| Closure | We fill in gaps to create complete objects | Seeing a circle even with gaps: ( ) |
| Common Fate | Objects moving together are grouped | Flock of birds perceived as one unit |
Monocular Cues (one eye)
- Relative Size: Smaller = farther
- Interposition: Overlapping objects
- Linear Perspective: Converging lines
- Texture Gradient: Less detail = farther
- Relative Height: Higher = farther
- Motion Parallax: Closer objects move faster
Binocular Cues (two eyes)
- Retinal Disparity: Different images in each eye; greater difference = closer object
- Convergence: Eyes turn inward for near objects; muscle tension provides distance cues
- Know the difference: Sensation (detection) vs. Perception (interpretation).
- Gestalt principles are frequently tested—memorize all six!
- Perceptual constancies: Size, shape, color, and brightness constancy help us perceive stable objects.
1) A radiologist looking at an X-ray uses their medical training to identify a tumor. Is this bottom-up or top-down processing?
2) Which Gestalt principle explains why we see "IBM" in a logo made of horizontal lines?
Show Answers
1) Top-down processing—they're using prior knowledge and expectations to interpret the sensory data.
2) Closure—we fill in the gaps to perceive complete letters even though they're made of separate lines.
Thinking, Problem-Solving, Judgments, and Decision-Making
Cognition involves the mental activities associated with thinking, knowing, remembering, and communicating. This section covers how we form concepts, solve problems, and make decisions.
| Strategy | Description |
|---|---|
| Trial and Error | Testing solutions until one works |
| Algorithm | Following a systematic procedure (e.g., solving a Rubik's cube with a formula) |
| Heuristics | Using rules of thumb (e.g., "If it looks like a duck...") |
| Insight | Sudden "aha!" realization of a solution |
🔒 Fixation
Mental Set: Tendency to use solutions that worked before, even when they're not optimal now.
Functional Fixedness: Inability to see objects as having functions beyond their typical use.
🎯 Confirmation Bias
Tendency to search for information that confirms our preexisting beliefs while ignoring contradictory evidence.
| Heuristic | Description | Example |
|---|---|---|
| Representativeness | Judging likelihood based on how well something matches a prototype | Assuming a shy person is more likely a librarian than a salesperson |
| Availability | Judging likelihood based on how easily examples come to mind | Overestimating plane crash deaths after seeing news coverage |
| Anchoring | Relying too heavily on the first piece of information (the "anchor") | Negotiating salary based on initial offer rather than market value |
- Algorithm vs. Heuristic: Algorithm = guaranteed but slow; Heuristic = fast but risky.
- The three heuristics (representativeness, availability, anchoring) are AP favorites!
- Functional fixedness often appears in FRQ scenarios—look for creative problem-solving contexts.
The Candle Problem: Given a candle, matches, and a box of tacks, attach the candle to the wall so wax doesn't drip on the table.
Solution: Empty the box, tack it to the wall, place candle inside.
Most people fail because they see the box only as a container for tacks, not as a potential shelf.
1) After seeing several news stories about shark attacks, Maria refuses to swim in the ocean. Which heuristic is at play?
2) A doctor initially diagnosed a patient with a rare disease because the symptoms perfectly matched the textbook description, ignoring that common diseases are more likely. Which heuristic?
Show Answers
1) Availability heuristic—recent media coverage makes shark attacks easily come to mind, leading to overestimation of the risk.
2) Representativeness heuristic—judging probability based on how well symptoms match a prototype, ignoring base rates (how common each disease actually is).
Introduction to Memory
Memory is the persistence of learning over time through encoding, storage, and retrieval of information. Without memory, we'd have no sense of personal history or identity.
The classic model of memory proposes three distinct memory systems:
📸 Sensory Memory
Iconic: Visual (lasts ~0.5 sec)
Echoic: Auditory (lasts ~3-4 sec)
💭 Working Memory
Active processing of incoming and retrieved info
Chunking increases capacity
🗄️ Long-Term Memory
Potentially permanent storage
Explicit (conscious) & Implicit (unconscious)
- Magic number 7±2: Miller's Law—short-term memory capacity.
- Chunking example: FBI-CIA-IBM is easier to remember than FBICIAIIBM.
- Working memory ≠ short-term memory: Working memory emphasizes active processing, not just storage.
1) You hear your name called across a crowded room. Which type of sensory memory initially holds this sound?
2) Why does rehearsal help transfer information to long-term memory?
Show Answers
1) Echoic memory—the brief sensory memory for auditory information.
2) Rehearsal keeps information active in working memory longer, giving more opportunity for encoding into long-term memory. Elaborative rehearsal (connecting to existing knowledge) is more effective than simple repetition.
Encoding Memories
Encoding is the first step in creating a memory—transforming sensory information into a form that can be stored. The deeper you process information, the better you'll remember it.
Memory depends on the depth of processing, not just time spent studying.
| Level | Type of Processing | Example | Memory Strength |
|---|---|---|---|
| Shallow | Structural (appearance) | "Is the word in capital letters?" | Weakest |
| Intermediate | Phonemic (sound) | "Does the word rhyme with train?" | Moderate |
| Deep | Semantic (meaning) | "Does the word fit in this sentence?" | Strongest |
🔄 Elaborative Rehearsal
Connecting new information to existing knowledge and experiences.
More effective than rote repetition!
📊 Chunking
Organizing information into meaningful groups.
Example: Phone numbers as XXX-XXX-XXXX
🏠 Method of Loci
Associating items with locations in a familiar place.
Ancient Greek memory palace technique
🔗 Mnemonic Devices
Memory aids using acronyms, rhymes, or visual associations.
ROY G. BIV for rainbow colors
Visual Encoding: Remembering what something looks like (imagery)
Acoustic Encoding: Remembering what something sounds like (phonetic)
Semantic Encoding: Remembering the meaning of something
Semantic encoding is most effective for long-term retention because it creates deeper, more meaningful connections.
- Spacing effect vs. massed practice: Spacing wins every time for long-term retention.
- Testing effect: Practice tests > re-reading notes.
- Dual coding: Combining verbal and visual information enhances memory.
1) A student remembers vocabulary words by creating a story using all the words. What encoding strategy is this?
2) Why does the testing effect work better than re-reading?
Show Answers
1) Elaborative rehearsal (and semantic encoding)—creating meaningful connections between words through narrative.
2) Testing requires active retrieval, which strengthens the neural pathways to the memory. Re-reading is passive and creates an illusion of knowing without actually practicing recall.
Storing Memories
Once information is encoded, it must be stored for later use. Different types of memories are stored in different brain systems and have different characteristics.
| Brain Structure | Role in Memory |
|---|---|
| Hippocampus | Encoding new explicit memories; memory consolidation |
| Amygdala | Emotional memories; enhances memory for emotional events |
| Cerebellum | Procedural memories; motor learning |
| Basal Ganglia | Procedural memories; habit formation |
| Prefrontal Cortex | Working memory; retrieval strategies |
Famous patient who had his hippocampus removed to treat epilepsy. Results:
- Could NOT form new explicit memories (anterograde amnesia)
- Could still recall old memories from before surgery
- Could still learn new procedural skills (like mirror tracing)
This proved the hippocampus is essential for forming new explicit memories but not for procedural memory or old memories.
- Explicit vs. Implicit: Can you consciously recall it? Yes = explicit. Is it automatic? Yes = implicit.
- Flashbulb memories: Vivid, detailed memories of emotionally significant events (9/11, JFK assassination). Seem accurate but can still be distorted.
- Know H.M.: His case is frequently referenced on AP exams!
1) Remembering how to type without looking at the keys is an example of what type of memory?
2) A patient with hippocampal damage can still remember their childhood but cannot form new memories of daily events. Explain why.
Show Answers
1) Procedural (implicit) memory—it's an automatic skill that doesn't require conscious recall.
2) The hippocampus is needed for encoding new explicit memories, but old memories have already been consolidated and are stored in the cortex. Damage prevents new memory formation but doesn't erase previously stored memories.
Retrieving Memories
Retrieval is the process of getting information out of memory storage. A memory isn't useful if you can't access it when needed!
📝 Recall
Retrieving information without cues.
Example: Fill-in-the-blank test
More difficult
✅ Recognition
Identifying previously learned information from options.
Example: Multiple choice test
Easier
| Effect | Description | Example |
|---|---|---|
| Context-Dependent Memory | Memory is better when retrieval occurs in same physical environment as encoding | Scuba divers recalled words better underwater if they learned them underwater |
| State-Dependent Memory | Memory is better when retrieval occurs in same mental/physical state | Studying while caffeinated → test while caffeinated |
| Mood-Congruent Memory | We recall memories consistent with our current mood | When sad, we remember other sad times more easily |
When recalling a list, we remember items at the beginning and end better than those in the middle.
Primacy Effect
Better recall of items at the beginning of a list.
Had more time to rehearse → transferred to LTM
Recency Effect
Better recall of items at the end of a list.
Still in working memory
Priming: Exposure to one stimulus influences response to a subsequent stimulus.
If you see the word "yellow," you'll recognize "banana" faster because the concepts are associated in memory.
Priming demonstrates that memories are connected in networks of associations.
- Recall vs. Recognition: Essay tests require recall; multiple choice tests use recognition.
- Serial position effect: Very common AP topic—know both primacy and recency!
- Tip-of-the-tongue phenomenon: Knowing you know something but can't quite retrieve it—demonstrates retrieval failure.
1) You studied for your exam in the library. According to context-dependent memory, where should you take the test?
2) Why do students remember the first and last items of a lecture better?
Show Answers
1) In the library (or a similar environment). Context-dependent memory suggests retrieval is enhanced when the physical environment matches the encoding environment.
2) Serial position effect: Primacy effect (first items had more rehearsal time) and recency effect (last items are still in working memory).
Forgetting and Other Memory Challenges
Forgetting isn't a flaw—it's actually adaptive! Imagine remembering every single detail of every day. But sometimes forgetting causes problems, and memory can be surprisingly unreliable.
| Theory | Explanation | Example |
|---|---|---|
| Encoding Failure | Information never entered long-term memory | Can't remember the image on a penny—never encoded it |
| Storage Decay | Memory trace fades over time without use | Forgetting high school Spanish after years of not using it |
| Retrieval Failure | Information is stored but can't be accessed | Tip-of-the-tongue phenomenon |
| Interference | Other memories block the target memory | Old and new phone numbers interfere |
⬅️ Proactive Interference
OLD interferes with NEW
Your old phone number makes it hard to remember your new one.
"Pro" = forward (old blocks new)
➡️ Retroactive Interference
NEW interferes with OLD
Learning your new phone number makes you forget your old one.
"Retro" = backward (new blocks old)
Retrograde Amnesia
Can't remember events BEFORE the trauma.
"Retro" = past
Anterograde Amnesia
Can't form NEW memories AFTER the trauma.
"Ante" = forward (like H.M.)
Loftus showed participants a video of a car accident. Those asked "How fast were the cars going when they smashed into each other?" estimated higher speeds than those asked about cars that "hit" each other.
A week later, "smashed" participants were more likely to falsely remember seeing broken glass.
This demonstrates how leading questions can create false memories—critical for understanding eyewitness testimony limitations.
- Proactive vs. Retroactive: Use the direction words! Pro = old → new; Retro = new → old.
- Ebbinghaus forgetting curve: Most forgetting happens quickly after learning, then levels off.
- Repression (Freud's concept): Motivated forgetting of painful memories—controversial and hard to prove.
1) After learning Spanish, you have difficulty remembering the French you learned in high school. What type of interference?
2) A crime witness is asked, "Did you see THE broken headlight?" vs. "Did you see A broken headlight?" Why does this matter?
Show Answers
1) Retroactive interference—new learning (Spanish) interferes with old learning (French).
2) Using "THE" implies there definitely was a broken headlight, which can create a false memory through the misinformation effect. Leading questions can distort eyewitness testimony.
Intelligence and Achievement
What is intelligence? This seemingly simple question has sparked decades of debate. Is it one thing or many? How do we measure it? Can it change?
| Theorist | Theory | Key Ideas |
|---|---|---|
| Spearman | General Intelligence (g) | One underlying factor influences all mental abilities |
| Thurstone | Primary Mental Abilities | Seven distinct abilities (verbal, numerical, spatial, etc.) |
| Gardner | Multiple Intelligences | Eight independent intelligences (linguistic, logical-mathematical, musical, spatial, bodily-kinesthetic, interpersonal, intrapersonal, naturalist) |
| Sternberg | Triarchic Theory | Three types: Analytical, Creative, Practical |
| Salovey & Mayer | Emotional Intelligence | Ability to perceive, understand, manage, and use emotions |
| Test | Description |
|---|---|
| Stanford-Binet | First widely used IQ test; originated from Binet's work in France |
| Wechsler Tests | WAIS (adults), WISC (children); most widely used today; measures verbal and performance IQ separately |
📏 Reliability
Consistency of results over time.
Does the test give the same score each time?
🎯 Validity
Does the test measure what it claims to measure?
Does it actually measure intelligence?
📊 Standardization
Uniform testing procedures and comparison norms.
Everyone takes it the same way
Evidence for Genetics (Nature):
- Identical twins have more similar IQs than fraternal twins
- Heritability estimates: 50-80%
- Adopted children's IQs correlate more with biological parents
Evidence for Environment (Nurture):
- Flynn Effect: IQ scores rising over generations
- Education, nutrition, and enrichment boost IQ
- Early intervention programs show lasting effects
Stereotype Threat: Awareness of a negative stereotype about one's group can impair performance on tasks related to that stereotype.
When women are reminded of the stereotype that "men are better at math" before a math test, their performance decreases—not because of ability, but because of the psychological burden of the stereotype.
This demonstrates how social factors influence test performance beyond actual ability.
- Gardner vs. Sternberg: Gardner = 8 types; Sternberg = 3 types (analytical, creative, practical).
- Reliability vs. Validity: A test can be reliable but not valid (consistently measuring the wrong thing).
- Flynn Effect: Key evidence that environment influences intelligence.
1) According to Sternberg's triarchic theory, what type of intelligence would help someone navigate office politics?
2) If a test has high reliability but low validity, what does that mean?
Show Answers
1) Practical intelligence—the ability to adapt to and succeed in everyday environments ("street smarts").
2) The test gives consistent results (same score each time) but does not actually measure what it claims to measure. For example, a "creativity test" that reliably measures memory instead.