Capacity (how much memory can be held)
Short term = limited.
Long Term = Potentially unlimited.
STM - participants given a list of numbers to see how many they can remember. Miller (1956) discovered that a weakness of this is that the number of words depend on the length of those words, he also concluded that the span of immediate memory is 7 +/- 2.
LTM - Holds vast information, can modify information.
STM, LTM & Duration
Duration (how long we can remember for)
Short term = Limited. Long term = Potentially unlimited
STM - Anything remmebered for a long time, must be transferred to the LTM by verbal rehearsal. Lloyd & Peterson found that the duration of the STM is 18 seconds.
LTM - Bahrick (1975) showed people photographs from high school 45 years later, they were able to remember 70% of names to faces. The LTM is a permastore.
Baddeley suggests that LTM encode semantically. & STM encodes acoustically.
Baddeley list of acoustically similar and not similar words, and found that participants confuse acoustically similar words and in the LTM would confuse semantically similar words.
Multi Store Model
Multi Store Model (Atkinson & Shiffin 1968)
Sensory Memory - Senses receive information, most is recieved and then decays.
STM store - Information is fragile, unless rehearsed, it decays. If rehearsed memory passes to the LTM.
LTM store - Some information lost due to decay, encodes semantically, capacity and duration are potentially unlimited.
Advantages of MSM = MSM says that memory flows through 3 separate stores, and there is empircal evidence to support separate stores.
Disadvantages of MSM = More than one store for both STM & LTM, contrast with WMM about stores for acoustic and visual, MSM only gives one way to transfer memories from STM & LTM. Craik & Lockhart (1972) memories are deeply processed. In the LTM, suggested episodic memories.
Working Memory Model
Working Memory Model ( Baddeley & Hitch 1974)
Suggest that a bit opf memory that you are using to do a complex task that requires you to store information as you go along.
Central Executive - Boss of the system, co-ordinates working memory as information comes in the central executive directs to the right part of the system. Central exec. has limited capacity and cannot process memories itself.
Visuo-spatial sketchpad - Holds information pictorally and helps us understand spatial awareness.
Phonological Loop - deals with sound.
- Phonological store - inner ear, and holds the words you hear. 2.
- Articulatory Control System - Inner voice, sub vocally repeats sounds from the Phonological Store to help recall.
Episodic Buffer - brings together information that relates both visual and acoustic stores.
Strengths & Weaknesses of WMM
- Lots of empirical evidence to support model.
- Sternberg (2006) "the wmm is accepted today"
- Explanation of central executive is vague.
- Much of supporting evidence for model is from case studies of patients with brain trauma.
- Evidence is not completely valid as you cannot accurately compare before and after the trauma.
Eye Witness Testimony
EWT - a legal term, a person gives evidence in court concerning the events of a crime.
The person must encode information in their LTM, store it for some time and then retrieve it.
Rattner (1988) reviewed 205 wrongful arrest case and found that in 52% of cases this was due to inaccurate eye witness testimonies.
Loftus & Palmer (1974)
Showed Participants a video of a car accident and then asked them questions about it. They found that participants gave a higher speed of the car if the researcher asked a question with an aggressive word (leading questions)
Loftus suggests that information we receive after an event permanently changes a memory. Two groups, 10 questions, 1 difference. "passed stop sign/barn" (Group 1/Group 2) Only 2.7% of group 1 answered yes compared to 17.3 %. Loftus concluded that memory had been added.
Anxiety of the Witness - Deffenbacher (2004) meta analysis concluded that high levels of stress negatively affect accurate recall of memories.
The Weapon Focus Effect - Loftus (1979) exposed participants to one of two situations.
1. Saw a person emerge from a lab holding a pen with grease on his hands after hearing a low key discussion of equipment failure.
2. Saw a man emerge holding a paper knife covered in blood following a heated exchange and sounds of smashing glass.
Participants were given 50 photos to identify the person they had seen. 1st group - 49% of the time. 2nd group - 33%. Loftus concludes that weapon focus was to blame, the person concentrates more on the weapon than on the perpetrator, also stress negatively affects recall.
However, Christianson & Hobinetter (1993) question bank robbery witnesses found that those whho were threatened had more accurate recall, as emotional arousal could actually improve recall.
Yerkes-Dodson Law - Medium levels of stress improve recall and high levels of stress will hinder recall.
Age - Parker & Carranza (1989) compared the recall of primary children and college students.
Participants watched slideshow of a mock crime and were asked to identify the key figure, children were more likely to make errors in their choice.
Memon et al (2003) compared 16-33 year old with 60-82 eye witnesses. Short term recall of events weas no different, but when the task was delayed a week, the older group were less accurate.
Why can we recognise people of a similar age more successfully?
Brigham & Malpass (1985) discovered the reason for this. They concluded that because we have more contact with them, so we become experts at processing their facial features and thus recognise them more easily.