Memory

Memory

1. Long term Memory

   • Capacity
     • LTM potentially has an infinite capacity.
     • Evaluation
   • Duration
     • Bahrick tested 400 people of various ages on their memory of classmates. A photo-recognition test consisted of 50 photos, some from the participants high school year book. Participants were asked to recall the names they could remember from ntheir graduating class.  Participants who were tested 15 years after graduation was 90% accurate. Participants who were tested 48 years after graduation was 70% accurate. Free recall was about 60% accurate after 15 years, dropping to 30% after 48 years. 
     • Evaluation
   • Coding
     • Baddeley- Participants had difficulty remembering acoustically similar words in STM but not LTM, whereas semantically similar words posed little problem for STM's but led to muddled LTMS's. Suggests that STM is largely encoded acoustically whereas LTM is largely encoded semantically.
     • Evaluation

2. Short term Memory

   • Capacity
     • It can be assessed using the digit span. Jacobs used the digit span to assess STM capacity. He found that the average span for digits was 9.3 items and 7.3 for letters. Jacobs suggests that it is easier to recall digits as there are only 9, whereas there are 26 letters. Capacity: 7 +/- 2 items
     • Evaluation
   • Duration
     • Petersons used 24 students to study the duration of STM. Each participant was tested over 8 trials. On each trial a participant was given a consonant syllable and a three digit number (e.g THX 512). They were asked to recall the consanant syllable after an interval of 3,6,9,12,15 or 18 seconds. During interval they had to count backwards to prevent rehearsal.  90% correct over 3 seconds20% correct after 9 seconds2% after 18 seconds.Suggests that STM has a very short duration, less than 18 secs, as long as verbal rehearsal is prevented. 15-30 seconds
     • Evaluation
   • Coding
     • Baddeley- Participants had difficulty remembering acoustically similar words in STM but not LTM, whereas semantically similar words posed little problem for STM's but led to muddled LTMS's. Suggests that STM is largely encoded acoustically whereas LTM is largely encoded semantically.
     • Evaluation

3. Key Terms

   • Capacity
     • This is a measure of how much can be held in a memory. It is represented in terms of bits of information, such as number of digits.
   • Coding
     • The way information is changed so that it can be stored n memory. Information enters the brain via the senses (eyes ears mouth). It is then stored in various forms, such as visual codes, acoustic codes or semantic codes (meaning of experience).
   • Duration
     • A measure of how long a memory lasts before it is no longer available.
   • LTM
     • Your memory for events that have happened in the past. This lasts anywhere from 2 minutes to 100 years. LTM has potentially unlimited duration and capacity and tends to be coded semantically.
   • STM
     • Your memory for immediate events. STMs are measured in seconds and minutes rather than hours and days, i.e a short duration. They disappear unless they are rehearsed. STM also has a limited capacity of around 4 items or chunks and tends to be coded acoustically. This type of memory is sometime referred to as working memory.

4. Multi-store Memory Model (MSM)

   • The multi store model (Atkinson, & Shiffrin 1968) describes memory in terms of information flowing through a system. Accordingly, it can be described as an information processing model (like a computer) with an input, process and output. Information is detected by the sense organs and enters the sensory memory. If attended to this information enters the short term memory.
   • Sensory Register
     • When an environmental stimulus is detected by the senses it is briefly available in what Atkinson and Shiffrin called the sensory registers.
   • Attention
     • If a persons attention is focused on one of the sensory stores, then the data is transferred to STM. Attention is the first step in remebering something.

5. The Working Memory Model (WMM)

6. Types of Long Term Memory