Stats and Studies

• Sperling (1960) - SR – Capacity (High)Showed a grid of letters for less than a second, average recall of 4. Capacity 10 items before decay

   
• Sperling (1960) - SR – Duration (up to 2s) found that information decays within 50 milliseconds.
• Baddely (1966) – STM – Coding

  Good recall of acoustically similar words so STM uses acoustic encoding.

  -       LTM - Coding

  Lists of 10 words one at a time, some semantically similar, others not. Tested immediately and then after a 20 minute delay. Found that after 20 mins, they did poorly on semantically similar words. This suggest we encode LTMs according to what they mean – so we get similar meaning things confused. Encoding semantic. 
• Miller (1956) – STM – Capacity7+/- 2. Chunking data helps memory 
• Jacobs (1987)

  Digit  span test, increased list by one digit until incorrect recall. Digit span – 9 and letters – 7
• Peterson & Peterson – STM – Duration

  8 trials given a consonant syllable after a 3 digit number for e.g THX 512. Asked to recall after intervals (3,6,9,12,15 or 18s). Count backwards from their 3 digit number. Found  the duration of the STM is 15-30 seconds as long as verbal rehearsal is prevented.
• Bahrick (1975 ) – LTM - Duration400 people, 17-74, photo recognition test consisted of 50 photos, from school yearbook. Free recall test, list the names they could remember of those in their graduating class. 

  Within 15 years of graduation were about 90% accurate in identifying faces. 

  After 48 years & 70% for photo recognition

  .Free recall = 60% accurate after 15 years & 30% after 48 years. Duration is unlimited.
• Baddeley et al (1975)

   found pps had more difficulty doing two visual tasks (tracking a light and describing the letter F)
• Braver et al,

   pps given a task involving the CE (‘n-back task’ which involves judging whether a current letter was seen in a previous trial),activity in the PFC increased as the task became harder
• STM - Patient KF had poor STM ability for verbal info but could process visual info(e.g. reading or hearing letters/digits)
• LTM - HM Could not recall stroking a dog half an hour before but did not need the concept of a dog explained to him. 
• LTM - CW episodic damaged but semantic and procedural in tact (play piano).
• Tulving

  Brain scan used - episodic and semantic memories were both recalled from the pre-frontal cortex; semantic in the left side and episodic in the right side. 
• Belleville (2006) 

  found trained pps with cognitive impairment and cognitive aging and performed better on 3 tests of episodic memory than controls. 
• McGeoch and McDonald Recall was better for very different stimuli.  learn a list of 10 words, then 2nd  list e.g. consonant syllables, 3-digit numbers, synonyms, antonyms or control (just rested). then they’d recall the 1st list. Independent measures design. Recall of the original list was worse in the condition with synonyms- showing the effect of similarity in RI. 
• Baddeley and Hitch

  rugby players who played more games had less accurate recall of team names and this was attributed to interference. 
• Godden and Baddeley -underwater/land (repeated measures)

  Carter and Cassidy –anti-histamine/not (independent measures)
• Loftus and Palmer

  45 American students watched 7 film clips of car accidents and were then given questionnaires about the accident. In the ‘critical question’ (the leading one). Participants were asked to describe how fast the cars were travelling. ‘About how fast were the cars going when they hit each other? Contacted 

  The leading question biased their eyewitness recall of the event. The verb ‘smashed’ suggested a faster speed than contacted.

   

  
• Gabbert

  60 students from the University of Aberdeen and 60 older adults recruited from a local community watched a video of a crime, a girl stealing money from a wallet. IMD- tested individually or pairs (co-witness group)

  71% recalled info they had not seen on questionnaire, when testing their memory of the event. 60% said that the girl was guilty.  Shows post-event discussion and the powerful effect this can have on the accuracy of eyewitness testimony.
• Anastasi and Rhodes

  older people were less accurate than younger people when giving eyewitness reports all age groups were more accurate when identifying people of their own age group (own-age bias)                                                    
• Johnson & Scott (1976): negative effect

  Pps invited to take part in a study. IMD, overheard a heated argument (+ broken glass for knife condition) and a man walked past either holding a greasy pen or a bloody knife. High anxiety condition led to less accurate recall. 33% correctly identified the man from 50 photos, compared to 49% in the low anxiety condition- weapon focus effect. 
• Yuille and Cutshall (1986): positive effect

  Real-life crime, the owner of a gun shop was shot dead. 13/21 witnesses agreed to take part. After 5 months, those most anxious (rated on a 7 point scale), their recall was most accurate. They could recall a higher number of details. 88% compared to 75% for the less-stressed group. Anxiety may enhance EWT- fight or flight increases awareness and alertness. 
• Yerkes-Dodson Law (1908)

   suggests that the relationship between performance and arousal/stress is curvilinear and looks like and ‘inverted U’. This means that performances increases with stress up to an optimal point where it starts to decrease drastically
• Kohnken et al (1999)

   meta-analysis of 50 studies found 81% increase in amount of correct info compared to police interviews. However 61% increase in incorrect info.
• Milne and Bull (2002)

   found all 4 techniques used singly produced more recall than a standard interview. But a combination of ‘report everything’ and ‘mental reinstatement’ produced better recall than any of the other techniques individually or combined
• Craik and Tulving (1975) showeddeep/elaborative processing creates longer memories than shallow processing