Studies

• Sensory memory

  Takes info from the sense organs and holds it in the same form
• Sensory memory

  • Holds information from the 5 senses
  • Visual information is held in iconic memory
• Sperling (1960) presented a grid of letters for less than a second. People recalled on average 4 letters. Capacity was 10 items but it decayed before they could report them.
• Sperling (1960) found that information in sensory memory decays within 50 milliseconds.
• Short-term memory (STM)

  Your memory for immediate events, measured in seconds and minutes rather than hours and days
• Baddeley (1966) found that words that were acoustically similar were not confused in STM. STM uses an acoustic code, storing words on basis of their sound.
• Capacity of STM

  • 7 plus or minus 2 items (5-9 items)
  • If we chunk things together we can remember more
• Joseph Jacobs (1887) found the average span for digits is 9 items and 7 letters in STM. Digits are easier to recall because there are 10 digits and 26 letters.
• Peterson and Peterson experiment

  1. Participant given a 3-digit number and consonant syllable

  2. Asked to recall the consonant syllable after a 3-18 second delay

  3. Had to count backwards from the 3-digit number during the delay

  4. Found duration of STM is 15-30 seconds if verbal rehearsal is prevented
• Long-term memory (LTM)

  Your memory of events that happened in the past
• Baddeley (1966) found that after 20 minutes, people did poorly on semantically similar words, suggesting LTM is encoded based on meaning.
• Encoding in LTM is semantic - meaning based.
• Bahrick (1975) found participants were about 90% accurate in identifying faces from their high school yearbook within 15 years, but only 70% after 48 years. Free recall was 60% accurate after 15 years and 30% after 48 years. Duration of LTM is unlimited.