Human Memory It is good to have an end to journey towards; but it is the journey that matters, in the end. Ursula K. Le Gui

Memory Process by which information is: –Acquired Encoding –Stored in the brain Storage –Later retrieved Retrieval –Eventually (possibly) forgotten

Information-Processing Model of Memory Computer as a model for our memory Three types of memory –Sensory memory –Short-term memory (STM) –Long-term memory (LTM) Can hold vast quantities of information for many years

Information-Processing Model of Memory Short-term memory Stimulus Sensory memory Long-term memory AttentionEncoding Retrieval Forgetting

Sensory Memory Stores all the stimuli that register on the senses Lasts up to three seconds Two types –Iconic memory Visual Usually lasts about 0.3 seconds Sperling’s tests (1960s) –Echoic memory (we’ll come back to this) Sensory Input Sensory Memory

Sperling’s Experiment Presented matrix of letters for 1/20 seconds –Report as many letters as possible Subjects recalled only half of the letters Was this because subjects didn’t have enough time to view entire matrix? –No How did Sperling know this?

Sperling’s Iconic Memory Experiment

Sperling’s Experiment Sounded low, medium or high tone immediately after matrix disappeared –Tone signaled 1 row to report –Recall was almost perfect Memory for images fades after 1/3 seconds or so, making report of entire display hard to do High Medium Low

Sensory Memory Echoic memory –Sensory memory for auditory input that lasts only 2 to 3 seconds Why do we need sensory memory?

Short-term Memory Function –Conscious processing of information –Attention is the key Limits what info comes under the spotlight of short-term memory at any given time AKA working memory Working or Short-term Memory Sensory Input Sensory Memory Attention

Memorize the following list of numbers:

Write down the numbers in order.

Now, try again…

Short-term Memory Limited capacity –Can hold 7 ± 2 items for about 20 seconds –Maintenance rehearsal The use of repetition to keep info in short-term memory CHUNK –Meaningful unit of information –Without rehearsal, we remember 4 ± 2 chunks –With rehearsal, we remember 7 ± 2 chunks –Ericsson & Chase (1982)

Long-term Memory Working or Short-term Memory Sensory Input Sensory Memory Attention Long-term memory Retrieval Once information passes from sensory to short-term memory, it can be encoded into long-term memory Encoding

Long-term memory - Encoding Elaborative rehearsal –A technique for transferring information into long- term memory by thinking about it in a deeper way Levels of processing –Semantic is more effective than visual or acoustic processing –Craik & Tulving (1975) Self-referent effect –By viewing new info as relevant to the self, we consider that info more fully and are better able to recall it

Long-term memory Procedural (Implicit) –Memories of behaviors, skills, etc. Demonstrated through behavior Declarative (Explicit) –Memories of facts Episodic – personal experiences tied to places & time Semantic – general knowledge –Semantic network

Semantic Networks Red Fire Cherry Roses Fire Engine Apples House Green Flowers Daisies Yellow Orange Truck Bus Ambulance Sunrise Sunsets Clouds

Retrieval –Process that controls flow of information from long-term to working memory store Explicit memory –The types of memory elicited through the conscious retrieval of recollections in response to direct questions Implicit memory –A nonconscious recollection of a prior experience that is revealed indirectly, by its effects on performance

Retrieval – Explicit Memory Free-recall test –A type of explicit memory task in which a person must reproduce information without the benefit of external cues Recognition task –A form of explicit memory retrieval in which items are presented to a person who must determine if they were previously encountered Retrieval failure –Tip-of-the-tongue (Brown & McNeill)

Retrieval – Explicit Memory Context-Dependent Memory –We are more successful at retrieving memories if we are in the same environment in which we stored them State-Dependent Memory –We are more successful at retrieving memories if we are in the same mood as when we stored them

Retrieval – Implicit Memory Showing knowledge of something without recognizing that we know it Research with amnesics Déjà vu –The illusion that a new situation is familiar Eyewitness testimony –Eyewitness transference Unintentional plagiarism

Forgetting If we remembered everything, we should on most occasions be as ill off as if we remembered nothing. William James Lack of encoding –Often, we don’t even encode the features necessary to ‘remember’ an object/event Decay –Memory traces erode with the passage of time –No longer a valid theory of forgetting –Jenkins & Dallenbach (1924)

Interference theory Forgetting is a result of some memories interfering with others –Proactive interference Old memories interfere with ability to remember new memories –Retroactive interference New memories interfere with ability to remember old memories –Interference is stronger when material is similar

Forgetting Repression –There are times when we are unable to remember painful past events –While there is no laboratory evidence for this, case studies suggest that memories can be repressed for a number of years and recovered in therapy

Memory Construction Schema theory –Preconceptions about persons, objects, or events that bias the way new information is interpreted and recalled Misinformation effect –The tendency to incorporate false postevent information into one’s memory of the event itself Illusory memories –People sometimes create memories that are completely false

Improving Memory Practice time –Distribute your studying over time Depth of processing –Spend ‘quality’ time studying Verbal mnemonics –Use rhyming or acronyms to reduce the amount of info to be stored

Improving Memory Method of loci –Items to be recalled are mentally placed in familiar locations Interference –Study right before sleeping & review all the material right before the exam –Allocate an uninterrupted chunk of time to one course Context reinstatement –Try to study in the same environment & mood in which you will be taking the exam