Sperling (1960)- Sensory memory
-Showed participants 12 letters in 3 rows for 50 milliseconds.
-People remembered seeing more than they could recall, but the image fades during the time is takes to report back.
-Decay happens very quickly in sensory memory and capacity is very limited.
Peterson and Peterson (1959)
Peterson and Peterson (1959)- Duration in short-term memory
-Participants were shown a consonant trigram and asked to count backwards out loud in threes from a specified number to stop them rehearsing the trigram. After intervals of 3,6,9,12,15,18 seconds the participants were asked to stop counting and repeat the trigram.
-Participants were able to recall about 80% of trigrams after a 3 second interval without rehearsal but their recall became progressively worse as the time intervals got longer, until after 18 seconds they could recall fewer than 10% correctly.
-Information decays repidly from STM when rehersal is prevented, duration is limited.
Jacobs (1887)- Capacity in short-term memory
-Presented digit strings to participants which incresed in lenght each time.
-Participants could recall about seven digits on average. This was supported by many subsequent studies such as Miller.
Conrad (1964)- Encoding in short-term memory
-Participants were shown a random sequence of six consonants in very rapid succession, and then asked to write them down immediately in the correct order. There were two conditions;
1) Letters were acoustically similar ( B, G, C)
2) Letters were acoustically dissimilar (F, J, X)
-Participants found it more difficult to recall strings of letters that sounded the same than letters that sounded different. They often subsituted one for the other.
-Visually presented information was encoded acoustically and caused confusion where it was similar.
Bahrick et al. (1975)
Bahrick et al. (1975)- Duration in long-term memory
-Tested the memory of 392 graduates of an American high school for their former class mates using picturesm matching names to pictures or using names with no pictures cue.
-Participants recalled very well up to about 34 years. Recall was better on recognition tasks rather than on free recall. After 47 years there was less recall on all tasks.
-Long-term memory has a very long duration. Accurate recall is better with recognition tests rather than free recall. Depth of learning affects duration of memory.
Baddeley (1966)- Encoding in long-term memory
-Participants were presented with a random sequence of ten words. Each list was presented 4 times and then recall was tested after a 20 minute interval, rehearsal was prevented. There were 4 types of list;
1) Acoustically similar (mad, map, mat)
2) Acoustically dissimilar (pen, cow, day)
3) Semantically similar (tall, high, big)
4) Semantically dissimilar (thin, late, safe)
-Acoustic similarity had no effect on recall but words that were similar in meaning were poorly recalled.
-LTM codes were mainly semantic (meaning).