Hockenbury Discovering Psychology 5th txtbk

248 CHAPTER 6 MemoryAlthough forgetting can be annoying, it does have adaptive value. Our mindswould be cluttered with mountains of useless information if we remembered thename of every person we’d ever met, or every word of every conversation we’d everhad (Kuhl & others, 2007).Psychologists define forgetting as the inability to remember information thatwas previously available. Note that this definition does not refer to the “loss” or“absence” of once-remembered information. While it’s tempting to think of forgettingas simply the gradual loss of information from long-term memory over time,you’ll see that this intuitively compelling view of forgetting is much too simplistic.And although psychologists have identified several factors that are involved in forgetting,exactly how—and why—forgetting occurs is still being actively researched(Dudai, 2004; Wixted, 2004).Hermann Ebbinghaus (1850–1909) Afterearning his Ph.D. in philosophy in 1873,Ebbinghaus worked as a private tutor forseveral years. It was during this time thathe conducted his famous research on thememory of nonsense syllables. In 1885, hepublished his results in Memory: A Contributionto Experimental Psychology. In thattext, Ebbinghaus observed, “Left to itself,every mental content gradually loses itscapacity for being revived. Facts crammedat examination time soon vanish, if theywere not sufficiently grounded by otherstudy and later subjected to a sufficient review.”Among his other notable contributions,he developed an early intelligencetest, called the Ebbinghaus CompletionTest (Lander, 1997).forgettingThe inability to recall information that waspreviously available.encoding failureThe inability to recall specific informationbecause of insufficient encoding of theinformation for storage in long-termmemory.Hermann EbbinghausThe Forgetting CurveGerman psychologist Hermann Ebbinghaus beganthe scientific study of forgetting in the 1870s.Because there was a seven-year gap between obtaininghis doctorate and his first university teachingposition, Ebbinghaus couldn’t use university studentsfor experimental subjects (Fancher, 1996). Soto study forgetting, Ebbinghaus had to rely on theonly available research subject: himself.Ebbinghaus’s goal was to determine how muchinformation was forgotten after different lengths oftime. But he wanted to make sure that he was studyingthe memory and forgetting of completely new material, rather than informationthat had preexisting associations in his memory. To solve this problem, Ebbinghaus(1885) created new material to memorize: thousands of nonsense syllables. A nonsensesyllable is a three-letter combination, made up of two consonants and a vowel, such asWIB or MEP. It almost sounds like a word, but it is meaningless.Ebbinghaus carefully noted how many times he had to repeat a list of 13 nonsensesyllables before he could recall the list perfectly. To give you a feeling for thistask, here’s a typical list:ROH, LEZ, SUW, QOV, XAR, KUF, WEP,BIW, CUL, TIX, QAP, WEJ, ZODOnce he had learned the nonsense syllables, Ebbinghaus tested his recall of themafter varying amounts of time, ranging from 20 minutes to 31 days. He plotted hisresults in the now-famous Ebbinghaus forgetting curve, shown in Figure 6.8.The Ebbinghaus forgetting curve reveals two distinct patterns in the relationshipbetween forgetting and the passage of time. First, much of what we forgetis lost relatively soon after we originally learned it. How quickly we forget materialdepends on several factors, such as how well the material was encoded in thefirst place, how meaningful the material was, and how often it was rehearsed.In general, if you learn something in a matter of minutes on just one occasion,most forgetting will occur very soon after the original learning—also in a matter ofminutes. However, if you spend many sessions over days or weeks encoding new informationinto memory, the period of most rapid forgetting will be the first severalweeks or months after such learning.Second, the Ebbinghaus forgetting curve shows that the amount of forgettingeventually levels off. As you can see in Figure 6.8, there’s very little difference betweenhow much Ebbinghaus forgot eight hours later and a month later. The informationthat is not quickly forgotten seems to be remarkably stable in memory overlong periods of time.