Understanding Human Memory: Types, Processes, and the Impact of Trauma

1. Human memory Recall of Tragic events Selective

2. Three types of memory • SENSOR MEMORY: acts as a buffer for stimuli received through the senses. Information passes through sensory memory into short-term memory by attention, thereby filtering the stimuli to only those of interest at a given time

3. 2. SHORT-TERM MEMORY decays rapidly (200ms) and has a limited capacity. Chunking of information can lead to an increase in the short-term memory capacity (ie: a hyphenated phone number is easier to remember than a single long number). Interference often causes disturbance in short-term memory retention

4. 3. LONG-TERM MEMORY is intended for storage of information over a long time. Information from short-term memory is transferred to it after a few seconds. • Two types of long-term memory: a) episodic: memory of events and experiences in a serial form b) semantic: a structured record of facts, concepts and skills that we have acquired

5. Memory Activities • There are three main activities related to long-term memory • Storage • Deletion • Retrieval

6. Storage • Information from short-term memory is stored in long-term memory by rehearsal • The repeated exposure to a stimulus or the rehearsal of a piece of information transfers it into long-term memory • Affected by passage of time, frequency and length of exposure and new information

7. Deletion • Mainly caused by decay and interference • Emotional factors also affect long-term memory

8. Retrieval • Two types of retrieval: • Recall: the information is reproduces from memory • Recognition: the presentation of the information provides the knowledge that the information has been seen before. This is less complex since the information is provided as a clue

9. Effects of trauma on memory • Marked deficiencies in memory may occur when individuals suffer either physical or psychological trauma • The extent of this is very individual • For some, there are unprocessed memories that may appear unexpectedly as flashbacks which are the unexpected and unwelcome reliving of a traumatic incident • May be triggered by a chance remark, sight, smell, sound, taste or touch

10. Post event information effect • After witnessing an event, we are exposed to new information that can actually change our memory • People can reconstruct inaccurate memories after witnessing an event as a result of discussing the event with others

11. Eyewitness testimony • Eyewitness testimony is, at best, evidence of what a witness believes to have occurred • Up to a 50% error rate • Memory is not a tape recorder • Ability to identify a stranger is diminished by distress • Cross racial identification unreliable • People who are certain are no better at it, just more confident

12. Impediments to memory • Ability to Judge time & distance • Age & health – sensory acuity • Personal bias & expectations • Viewing conditions

13. After the incident • Make notes as soon as possible • Write them alone • Don’t discuss the incident • You may be asked to give a statement to police - you may give information other than the person’s medical history & findings - you may be called as a witness in court to recall statements made by the patient