Coding, Capacity and Duration

Ever wondered why you can remember song lyrics perfectly but struggle with your shopping list? It's all about how your brain codes information - basically, the format it uses to store memories.

Your short-term memory (STM) loves sound - it codes information acoustically. That's why you might confuse words that sound similar when you're trying to remember them quickly. Long-term memory (LTM), however, is all about meaning - it codes semantically, focusing on what things actually mean rather than how they sound.

Baddeley's 1966 study proved this brilliantly. He gave people four types of word lists to remember - some that sounded similar, some that sounded different, some with similar meanings, and some with different meanings. When people had to recall immediately, they struggled with similar-sounding words. But after 20 minutes, they had more trouble with words that had similar meanings. This shows your STM and LTM work completely differently.

Capacity is where things get interesting. Your STM is ridiculously limited - only 5-9 items on average. Jacobs (1887) found people could remember about 9 digits and 7 letters before their memory gave up. Miller (1956) noticed everything comes in sevens and suggested we can boost our STM through chunking - grouping information into meaningful units.

Quick tip: Try chunking your revision notes into groups of 7 or fewer points - your brain will thank you for it!

Multi-Store Model and Types of Long-Term Memory

The Multi-Store Model treats your memory like a factory production line. Information flows from your sensory register (which holds everything you see and hear for about half a second) into your STM through attention, then into LTM through rehearsal.

Think of your STM as a temporary workspace - it holds information for about 30 seconds and has space for roughly 7 items. Maintenance rehearsal is like keeping plates spinning - you repeat information to keep it active. Your LTM is the ultimate storage warehouse with unlimited capacity and potentially permanent duration.

Baddeley's research supports this model beautifully. We mix up similar-sounding words in STM but confuse similar-meaning words in LTM, proving these are genuinely different systems working in completely different ways.

Your LTM isn't just one massive filing cabinet - it's actually three distinct systems. Episodic memory stores your personal experiences (like your first day at college), complete with timestamps and emotional context. Semantic memory holds your knowledge about the world (like knowing London is England's capital). Procedural memory handles your skills (like riding a bike or typing).

Real-world relevance: Understanding these memory types helps explain why someone with dementia might forget recent events but still remember how to play piano perfectly.

The evidence is rock-solid. Tulving's brain scans showed different areas lighting up for different memory types, while case studies of patients like HM and Clive Wearing revealed that brain damage can destroy one type of memory while leaving others completely intact.

Working Memory Model

Forget the idea that your short-term memory is just a simple storage box - it's actually a sophisticated multi-tasking system called working memory. Baddeley and Hitch (1974) revolutionised our understanding by showing that your STM actively processes different types of information simultaneously.

The central executive is like your brain's CEO, making decisions about what information gets attention and coordinating three specialist departments. The phonological loop handles all sound-based information, storing what you hear for about 2 seconds. The visuo-spatial sketchpad processes visual and spatial information - think of it as your mind's inner eye that can hold 3-4 objects.

The episodic buffer is the newest addition - a temporary mixing desk that combines information from all sources and links working memory to your long-term storage. It's modality free, meaning it can handle any type of information, and holds about 4 chunks of data.

Clinical evidence strongly supports this model. KF, a brain-damaged patient studied by Shallice and Warrington, had perfectly normal visual processing but couldn't handle verbal information - proving these systems operate independently. Dual-task studies by Baddeley showed people struggle more doing two visual tasks together than mixing visual and verbal tasks, because they're competing for the same processing system.

Study hack: This explains why you can listen to instrumental music while reading (different systems) but struggle to read while someone's talking (same phonological system)!

The model isn't perfect though - critics argue the central executive is too vague and doesn't really explain how attention actually works.

Interference Theory

Sometimes forgetting isn't about your memory fading - it's about memories getting in each other's way. Interference theory suggests that similar memories compete with each other, and sometimes one memory blocks another completely.

Proactive interference happens when old memories mess with new ones. Imagine a teacher who's learned hundreds of student names over the years - all those old names make it harder to remember her current class. Retroactive interference works backwards - new memories interfere with old ones, like when learning this year's students makes her forget last year's names.

McGeoch and McDonald's (1931) classic study proved that similarity is the killer. They had participants learn word lists, then gave them different types of second lists to learn. The most interference happened when the lists contained synonyms - words with similar meanings. The more similar the material, the more forgetting occurred.

Thousands of lab experiments support interference theory, giving psychologists confidence it's a valid explanation for forgetting. Baddeley and Hitch's (1977) rugby study brilliantly showed this works in real life - players remembered matches better based on how many games they'd played since, not how much time had passed.

Revision reality check: This explains why studying similar subjects back-to-back (like History and Politics) can be counterproductive - the information interferes with each other.

The main criticism is that most research uses artificial word lists that don't reflect real-life memory tasks. Learning random words is quite different from remembering faces, birthdays, or practical skills you actually use.

Retrieval Failure

Your memories aren't lost - they're just badly filed. Retrieval failure theory suggests we forget because we can't find the right cues to access our memories. Tulving's encoding specificity principle is beautifully simple: the more similar your retrieval situation is to when you originally learned something, the better you'll remember it.

Context-dependent forgetting happens when your physical environment changes. Godden and Baddeley's (1975) underwater experiment is legendary - divers who learned word lists underwater remembered 40% more when tested underwater rather than on land. Your brain automatically links memories to environmental cues without you realising it.

State-dependent forgetting occurs when your internal state changes. Carter and Cassaday (1998) gave participants antihistamines that made them drowsy, then tested their memory in matching or mismatched states. Performance dropped significantly when learning and recall states didn't match.

The research support is impressive - Eysenck (2010) argues that retrieval failure is the main reason we forget from long-term memory. This makes it incredibly relevant for understanding everyday forgetting experiences.

Practical application: Try revising in different locations and states - you never know what environmental cues might be available during your actual exam!

However, Baddeley (1997) argues that context effects aren't that strong in real life. You need dramatically different environments (like underwater vs land) to see major effects. Simply changing rooms usually won't cause much forgetting because most environments aren't different enough. Also, context effects mainly work for recall tests but disappear with recognition tests, limiting their real-world application.

Misleading Information and Eyewitness Testimony

Your memory isn't a recording device - it's more like a Wikipedia page that anyone can edit. Misleading information can genuinely change what you remember about events, which has massive implications for criminal justice.

Loftus and Palmer's (1974) car crash study is psychology gold. They showed participants accident footage, then asked about speed using different verbs - "contacted," "bumped," "collided," "hit," or "smashed." The word "smashed" produced speed estimates of 40.5mph, while "contacted" only got 31.8mph. Even more dramatically, participants who heard "smashed" later claimed they saw broken glass that wasn't even in the original footage.

This happens through substitution - the misleading information actually overwrites your original memory rather than just influencing how you answer. It's genuinely scary how easily memories can be altered.

Post-event discussion is equally dangerous. Gabbert's (2003) study had participants watch the same crime from different viewpoints, then discuss what they saw. A staggering 71% incorporated details they never actually witnessed but heard from others. The control group with no discussion? 0% false memories.

Real-world impact: This research has transformed police interviewing techniques and highlighted the dangers of leading questions in criminal investigations.

Critics argue that watching accident footage lacks the emotional intensity of real events, potentially making people more susceptible to suggestion than they would be after genuine trauma. There are also individual differences - Anastasi and Rhodes (2006) found older adults are less accurate than younger people, and everyone's better at identifying people their own age.

Anxiety and Eyewitness Testimony

Anxiety can make your memory laser-focused or completely useless - it all depends on the level and context. This matters enormously when eyewitnesses are trying to recall crimes they've experienced.

Weapon focus effect suggests high anxiety narrows your attention tunnel. Johnson and Scott's (1976) classic study had participants overhear an argument, then see someone emerge either holding a bloody knife or a pen with grease. Only 33% could later identify the man with the knife compared to 49% who saw the pen. The weapon grabbed their attention, reducing their ability to encode other details.

However, moderate anxiety can actually improve memory. The fight-or-flight response increases alertness and awareness, potentially making you a better witness. Yuille and Cutshall's (1986) real-world study of a gun shop shooting found that witnesses with the highest stress levels were actually the most accurate, even 4-5 months later.

The relationship between anxiety and memory follows an inverted-U shape - too little anxiety means you're not paying attention, too much anxiety overwhelms your system, but moderate levels can optimise performance.

Key insight: Real crimes create different anxiety responses than lab simulations, making field studies crucial for understanding genuine eyewitness experiences.

Wicke's (1999) research challenged weapon focus by showing it might just be about unusualness rather than threat. Participants were equally distracted by unusual but harmless objects (like raw chickens in hair salons) as by weapons, suggesting the effect isn't specifically about anxiety.

Ethical concerns limit anxiety research - deliberately distressing participants purely for research violates psychological ethics, making real-world studies both more valuable and more challenging to conduct.

Cognitive Interview

The cognitive interview revolutionised police questioning by applying memory research to real-world criminal investigations. Fisher and Geiselman (1992) developed four evidence-based techniques that significantly improve eyewitness recall.

"Report everything" encourages witnesses to share every detail, no matter how trivial it seems. Seemingly unimportant information often triggers other crucial memories and provides investigators with leads they might otherwise miss.

"Reinstate the context" uses context-dependent memory principles - witnesses mentally return to the crime scene, imagining the environment, sounds, smells, and their emotional state. This recreates the original encoding conditions to improve retrieval.

"Reverse the order" prevents witnesses from filling gaps with expectations or assumptions. Recalling events backwards disrupts schemas and makes it harder to create false but plausible narratives, increasing accuracy while making deception more difficult.

"Change perspective" asks witnesses to describe events from different viewpoints, disrupting the influence of preconceptions and schemas that might distort genuine memories.

The enhanced cognitive interview adds crucial social elements - building rapport with witnesses, reducing anxiety, minimising distractions, and asking open-ended rather than leading questions.

Proven effectiveness: Köhnken's (1999) meta-analysis confirmed the enhanced CI consistently produces more correct information than standard police interviews.

Milne and Bull (2002) found that combining "report everything" with "context reinstatement" produces the best results, suggesting police can gain benefits even without using all four techniques. However, the CI is time-consuming and requires specialist training, making many police forces reluctant to implement it fully despite its proven effectiveness.