Experimental Psychology PSY 433 Chapter 10 Memory

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Ebbinghaus’s Techniques Nonsense syllables – controls for prior experience and knowledge of meanings. Trials to criterion – keep practicing until the words are perfectly learned, count trials needed. Savings score – percentage of trials saved in relearning a list, relative to original trials needed. Example: 10 – 5 / 10 x 100% = 50% 10 original learning (OL), 5 relearning (RL)

Ebbinghaus Forgetting Curve

Varieties of Memory Short-term vs long-term memory Atkinson & Shiffrin’s 3-stage model Procedural vs declarative (semantic) Memory for doing things vs knowledge of facts Explicit (episodic & semantic) vs implicit memory Squire’s idea that consciousness makes a difference. Implicit includes procedural memory but also priming

Atkinson & Shiffrin’s Model

Squire’s Model

Name the Seven Dwarfs

Is it easier with the picture?

A Recognition Task Which of the following are names of the Seven Dwarfs? Goofy Bashful Sleepy Meanie Smarty Doc Scaredy Happy Dopey Angry Grumpy Sneezy Wheezy Crazy

Dependent Variables Recall -- % or proportion remembered Serial recall Free recall Paired-associates recall Recognition -- % or proportion remembered Yes/No Forced choice (multiple choice) Primed recognition– e.g., stem completion

Independent Variables The kind of material to be remembered: Letters, digits, nonsense syllables, words, phrases, sentences, paragraphs, passages of prose. Retention interval – how fast does forgetting occur? Modality of presentation – visual vs verbal. Encoding strategies Type of test – recall vs recognition.

Control Variables Amount and type of material presented. Concreteness vs abstractness of words. Rate of presentation. Modality of presentation – eyes, ears. Each of these could also be an IV – but do not vary everything in the same experiment. Whatever is varied, the other aspects should be controlled.

Scale Attenuation Effects Memory experiments are especially sensitive to difficulty of the task: Ceiling effects occur when the task is too easy and everything gets nearly 100% correct. Floor effects occur when the task is too difficult and few people get any questions correct. Aim for 80% correct in the control group. Test your items before manipulating the IV.

Scarborough’s Experiment Used the Brown-Peterson technique to measure short-term memory: A trigram is followed by distractor task after a certain number of seconds. Percentage correct is measured Proactive interference makes the task difficult: trigrams seen on previous tasks interfere with remembering subsequent trigrams.

Scarborough’s Design Do we remember info better if we see it or hear it – does modality of presentation matter? IV 1 – Presentation modality: Visual Only group saw the trigrams Auditory Only group heard the trigrams read aloud Both group saw and heard the trigrams. IV 2 – Retention interval: 0, 3, 6, 9, 12, 18 sec DV – Proportion correctly recalled.

Which condition did better?

Scarborough’s Results Subjects who only saw the trigrams did as well as subjects who both saw and heard the trigrams. Subjects who only heard the trigrams did worse than those who saw or both saw and heard them. Seeing produces better retention than hearing.

Different Rates of Forgetting? Decline in retention appears steeper for those who only heard the trigrams. Does this mean auditory presentation results in faster forgetting? A ceiling effect complicates this interpretation. All three modalities are at 100% at 0 sec. With a higher ceiling, the decline for visual modality might have shown the same slope as for auditory.

Weight Loss Example Two men make a bet about who can lose the most weight. They weigh themselves on a scale that tops out at 300 lbs. Both weigh 300 lbs on the scale, although one actually weighs 350 while the other truly weighs 300. Both lose 100 lbs, so one now weighs 200 while the other weighs 250. Who won the bet?

Pilot Studies are Important! Avoid extremes of performance (high or low) by testing materials on pilot subjects. Make the task more difficult by increasing the amount of material to be remembered, presenting it faster, testing after a longer time interval, etc. Make the task easier by decreasing material, slowing down presentation rate, etc.