Memory

Coding is the format that memory is stored in.

Baddeley's research - word lists - four groups

acoustically similar, acoustically dissimilar, semantically similar and semantically dissimilar

ppts were asked to recall the words in the correct order.

STM recall (immediately after) had poor recall on acoustically similar words whereas LTM recall (after 20 minutes) had poor recall on semantically similar words

STM - coded acoustically

LTM - coded semantically

Capacity is how much information the memory store can hold at any one time.

Jacob's research - digit span - ppt is given digits and they have to recall them in the correct order if they get it correct the amount of digits increases, it stops when the ppt is no longer able to correctly recall the digits. The mean average digit span was 9.3 and the mean span for letters was 7.3.

Miller's research - Made the observation that things come in sevens e.g. 7 days of the week and 7 deadly sins. He suggested that the span (capacity) for STM was about 7 items ( or 7 +/- 2 ( 5-9 ) )

Miller also observed that people can recall 5 words as well as they can 5 letters. They do this by chunking - grouping sets of digits or letters into units or chunks

Peterson & Peterson's research - Duration of STM - Trigram recall - Each ppt was given a consonant syllable (e.g. YCG) and a 3-digit number, ppts were asked to count down from the 3-digit number until told to stop which prevented mental rehearsal of the trigram.

Each test had a different retention interval (3, 6, 9, 12, 15 or 18 seconds).

They found that STM's duration is extremely short unless we repeat the information over in our heads (rehearsal)

Bahrick et al research - Duration of LTM - Used yearbook photos to test LTM recall in ppts aged 17-74. They used photo-recognition tests (using 50 photos from the yearbooks) and free recall where ppts recalled the names of their year group.

They found that ppts tested within 15 years of graduation were about 90% accurate in photo recognition. Ppts tested after 48 years had a photo recall rate of around 70%. Free recall was worse with 60% accuracy of ppts tested within 15 years and 30% for those tested after 48 years. 

This shows that the duration of LTM can last a lifetime.

Sensory register - Environmental stimuli will pas into the sensory registers e.g. sights, sounds, smells. There is a register for each of our 5 senses. The two main stores are the iconic memory (visual info) and echoic memory (auditory info). The duration of this memory store is less than half a second however it has a high capacity e.g. there are over 100 million cells in one eye which each store data. Very little of what goes into this register passes further into the memory system but it will if you pay attention to it.

STM - Limited capacity store (between 5-9 items) - info is coded acoustically - info lasts for about 30 seconds unless it is rehearsed. Maintenance rehearsal occurs when we rehearse material to ourselves repeatedly; if it is rehearsed long enough it will transfer into the LTM.

LTM - Potentially permanent memory store with unlimited capacity - info is coded semantically. When we want to recall LTM info we must transfer it to the STM by a process called retrieval. Memories and info are not recalled directly from LTM.

Tulving said that the multi-store model's view of LTM was too simplistic an inflexible and proposed that there are three LTM stores that store different types of info: Episodic, semantic and procedural

Episodic memory - Refers to our ability to recall events from our lives e.g. a birthday party. These memories are 'time-stamped' so you can recall when they happened. They include several elements such as, people and places, objects and behaviours which are all woven to produce a single memory. Lastly, a conscious effort has to be made to recall these memories.

Semantic memory - Contains our knowledge of the world e.g. the capital of France is Paris. It is similar to an encyclopaedia and dictionary and also includes concepts such as 'animals' and 'love'. These memories aren't time-stamped so we can't recall when we learned these things.

Procedural memory - This is our memory for actions/skills. We can recall these memories without conscious awareness or a great deal of effort. e.g. driving a car can become second nature once it has been learned for example a person will be able to change gear without having to recall how to. We may find these skills hard to explain to someone else as we do them naturally.

The working memory model focuses on STM and how it is organised and how it functions. It consists of four main components, central executive, phonological loop, visuo-spatial sketchpad and the episodic buffer. 

Central executive - Is an attention process that monitors incoming data and makes decisions and allocates tasks to the slave systems - It has a very limited processing capacity.

Phonological loop - Processes auditory information (coding is acoustic) and preserves the order in which the info arrives - It has two subdivisions: The phonological store (which stores words you hear) and the articulatory process (which allows maintenance rehearsal. The loop is believed to have a two-second capacity).

Visuo-spatial sketchpad - Stores visual/spatial info e.g. when you work out how many rooms are in your house you visualise it. It has a limited capacity ( about 3/4 objects) - it also has two sub-divisions; The visual cache (stores visual data) and the inner scribe (records the arrangement of objects in the visual field.

Episodic buffer - Added in 200 this store integrates visual, spatial and verbal info and records events that are happening - it can be seen as the CE's storage and has a capacity of 3/4 chunks. It links the WMM to LTM and wider cognitive processes such as perception.

Interference is when two pieces of information conflict with each other resulting in forgetting one or both pieces of info or distortion of memory. It is mainly linked to LTM recall as it is permanent so any form of forgetting these memories are most likely because we can't access them even though they are available. Interference makes it hard for us to locate memories and therefore 'forget' them.

Types of interference - It is likely that the memories interfering with each other were stored at different times so psychologists recognise that there are two types of interference: Proactive interference (an older memory interferes with a newer one) and Retroactive interference (a new memory interferes with an older one)

Effects of similarity - In both cases, interference is worse when the memories are similar as discovered by McGeoch and McDonald. - They studied retroactive interference with 6 groups, each group had a list of 10 words and had to recall them with 100% accuracy. They then learned a new list of either: Synonyms, antonyms, unrelated words, nonsense syllables, three-digit numbers or no new list. 

They found that when ppts recalled the original list of words, their performance depended on the nature of the second list. The most similar material produced the worst recall. This shows that interference is strongest when the memories are similar.

Retrieval failure is when people forget because of insufficient cues. When a memory is created, associates cues are stored at the same time, if these cues aren't available at the time of recall it may appear that you have forgotten the info but it is due to retrieval failure and not being able to access the memories that are there.

Encoding specificity principle - Tulving noted a pattern in research findings and called it the ESP which states that if a cue is to help us to recall info it had to be present at encoding and at retrieval. It says that if the cues available at encoding and retrieval are different or the cues are absent there will be some forgetting.  

Context-dependent forgetting - Godden and Baddeley studied deep sea divers working underwater  - Four conditions to learn word lists - learn on land recall on land, learn on land recall underwater, learn underwater recall underwater, learn underwater recall on land

They found that recall was 40% lower in the non-matching condition - environmental cues are important for retrieval

State-dependent forgetting - Carter and Cassaday completed similar study but with antihistamine drugs as they have a mild sedative effect - when conditions matched for learning and recall memory performance was significantly better.

Loftus and Palmer asked ppts to watch clips of car accidents and then asked questions about the crash. There was a critical question in this set which was a leading question - "how fast were the cars going when they hit each other?" - the verb hit made suggestions about the speed the car was going. There were five groups of ppts and each was given a different verb in the leading question: Hit, contacted, bumped, collided or smashed.

The found that the mean estimate speed using the verb contacted was 31.8mph whereas the verb smashed had a mean speed of 40.5mph which shows that the way we ask questions can be biased and mislead people.

The response bias explanation suggests that the wording of the question has no effect on the ppt's memories but it influences how they decide to answer. 

They conducted a second study that supported the substitution explanation - the wording of the question actually changes the ppts memory of the clip. This was demonstrated by the fact that ppts who heard smashed were more likely report seeing broken glass than those who heard it. The critical verb altered their memory of the incident.

When co-witnesses to a crime discuss it with each other their EWT may become contaminated. This is because they combine (mis)information from others with their own memories.

Gabbert et al studied ppts in airs. each ppt watched the same crime but from different angles meaning that one ppt could see things that the other couldn't, for example, the title of a book a woman was holding. Both ppts then discussed what they had seen and then individually completed a recall test.

They found that 71% of the ppts recalled information that they didn't see themselves but found out through discussion. The control group, who had no discussion,  had a figure of 0%.

Gabbert et al concluded that witnesses go along with other witnesses to either gain social approval or because they believe them. This is called memory conformity

Negative effect - Anxiety creates physiological arousal in the body which prevents us paying attention to important cues which affects recall. Johnson & Scott - lead a lad study where ppts sat in a waiting room whilst overhearing an argument next door. The low anxiety condition saw a man walk through the waiting area carrying a pen with grease on his hands. The high anxiety condition heard the same argument but also heard breaking glass and saw a man carrying a letter opener with blood on it.

They found that 49% of ppts who saw him carrying a pen were able to identify him from a set of 50 photos whereas in the other group only 33% could identify him. The tunnel theory suggests that witness's attention narrows to focus on a weapon because it's a source of anxiety.

Positive effect - Yuille & Cutshall conducted a study of a real-life shooting in a gun shop. The owner shot a thief dead with 21 witnesses, 13 agreed to the study. Interviews were held 4-5 months after the incident and were compared against police interviews taken at the time. Accuracy was determined by the amount of details reported. They were also asked to rate their stress level on a 7 point scale and if they have had any remaining emotional problems.

They found that those who reported the highest levels of stress were the most accurate - about 88% compared to 75% for the less-stressed group.

Explaining contradictory findings - Yerkes and Dodson said that the relationship between emotional arousal and performance looks like an inverted U.

Deffenbacher applied the Yerkes-Dodson law to EWT. Lower levels of anxiety produce lower levels of recall accuracy but memory becomes more accurate as the level of accuracy experienced increases, as the graph predicts. However, there is a point where the optimal level of anxiety is reached. This is the point of maximum accuracy if an eyewitness experiences a higher level of anxiety than their then their recollection of the event can decline.

Fisher and Geiselman argued that EWT could be improved if the police used better techniques when interviewing witnesses. They called these techniques the cognitive interview, there are four main techniques - report everything, reinstate the context, reverse the order and change perspective.

Report everything - Witnesses are asked to include every detail they can remember, even trivial things could be important, they could also trigger important memories.

Reinstate the context - The witness is asked to return to the crime scene in their mind and imagine their environment and the emotions they were feeling, this links to context-dependent forgetting

Reverse the order - If events are recalled in a different chronological order to the original sequence it prevents witnesses from reporting their expectations and dishonesty

Change perspective - If a witness reports an event from a different perspective it helps to disrupt the effects of expectations and schema on recall

Enhanced cognitive interview  (ECI) - Fisher et al added elements of the CI to focus on the social dynamics of the interaction e.g. when to establish eye contact and when to break it or asking open-ended questions.