CogLab #3

False Memory

. A surprising finding is that there is no way to assess memory accuracy without objective evidence (such as a tape recording or a photograph). This experiment demonstrates one methodology that biases people to recall things that did not occur. The memories associated with experiments of this type are often called false memories. The independent variable in this experiment was the type of word presented at test: (1) original list item, (2) unrelated distractor not on list, and (3) related distractor not on list. The dependent variable was the percentage of each type of item reported. The effect is quite robust and perhaps most surprisingly, it works well even when participants know what the experiment is about.

Serial Position

A ubiquitous finding is that this results in a ∪-shaped serial position function in which the first few items in the series are well remembered (the primacy effect), the last few items in the series are well remembered (the recency effect), but mid-list items are not remembered nearly as well. The serial position function is observed with many different kinds items, including letters, words, pictures, and even lists of items in your general knowledge such as the Presidents of the United States or the order of the Harry Potter books (Kelley et al., 2013). Because serial position functions are so commonly observed, they have played a major role in the development of memory theories. INDEPENDENT VARIABLE: serial position of the item DEPENDENT VARIABLE: proportion of times each letter was recalled People typically recall the last few items best (the recency effect), the first few items second best (the primacy effect), and the middle items worst. The effect is quite robust, but the exact shape of the serial position function depends on both the rehearsal strategy and the output order

Level of Processing

Craik and Lockhart (1972) stressed four points in the development of their Levels of Processing framework. First, they said that memory was the result of a successive series of analyses, each at a deeper level than the previous one. A shallow level of processing could be focusing on how a word sounds; a deeper level of processing could be focusing on the meaning of a word. Second, Craik and Lockhart assumed that the deeper the level of processing, the more durable the resulting memory. Third, the levels of processing view assumes that rehearsal can be relatively unimportant. A lot of rehearsal using a shallow level of processing will lead to worse memory than much less rehearsal using a deep level of processing. The final point had to do with how memory should be studied: The emphasis is on processing (what people are doing when they are presented with the items) rather than on structure (trying to work out which memory system is storing the information). According to the proceduralist view, the first row is irrelevant because it adds nothing to the explanation. The typical levels of processing experiment uses incidental learning. A participant is asked to rate words based on the number of letters or consonants, or on the words' pleasantness. Because the participant is unaware that there will be a memory test later, the experimenter can assume that once the rating task is over, the participant will not process the item further In Phase I, you will see a word and a judgment task. There are three types of judgment tasks. In Phase II, you will be shown a series of words, half of which were shown in Phase I, and half of which are new words. For each word, please answer the question, "Was this word in Phase I?" There are 120 words shown in Phase II. INDEPENDENT VARIABLE: level of processing induced by the orienting task shallow (the letters task), medium (the rhyme task), and deep (the semantic task). DEPENDENT VARIABLE: the proportion of times the word was correctly recognized as being in Phase I. People should correctly recognize more words with the deep processing task and fewest words with the shallow processing task. The reason is that on a standard recognition task, most people use semantic information as a cue to retrieval, and the type of processing most appropriate for a semantically-driven task is also semantic processing at test. EFFECT: The effect is quite robust and is not limited to recognition tests

Brown-Peterson

In the memory task, the participant saw a "consonant trigram" (three such as GKT or WCH) and then engaged in a distractor task. The purpose of the task was to prevent rehearsal, and the task chosen was counting backwards by 3 or 4 from a 3-digit number. The distractor task lasted between 3 and 18 s. The data showed that the probability of correctly recalling the trigram decreased as the length of the distractor task increased. The conclusion was that there exists a short-term memory (STM) system that holds information for several seconds. Without an active effort by the participant, information in STM fades away (but see Keppel & Underwood, 1962, for an alternate explanation). Performing the distractor task prevented the participant from actively rehearsing the trigram. INDEPENDENT VARIABLE: duration of the distractor test DEPENDENT VARIABLE: percent correct recall of the trigram the distractor task interferes with your ability to actively rehearse the trigram of letters. That is, you cannot do the distractor task and simultaneously repeat the trigram over and over to yourself. Thus, the task was thought to measure how long information stayed in short-term memory when rehearsal is not possible. The answer was not very long (on the order of 20 s or so), and so initially researchers proposed decay as an explanation: items in short-term memory decay unless rehearsed. Subsequent research suggested that the Brown-Peterson task is prone to proactive interference: doing so many trials with the same type of to-be-remembered items on every trial makes the task harder the more trials you do The expected result can be found for nearly everyone, as long as the distractor task is sufficiently complicated and as long as the participant actively engages in the task.

Memory Span

The memory span experiment is one measure of working memory capacity. In this experiment, participants are given a list of items and asked to recall the list. The list length is varied to see at what list length participants will make make few errors. That list length is the memory span for that person on that task. The very existence of short-term memory is largely based on memory span types of experiments, as it was noted that memory span was approximately seven items (plus or minus two) for a wide variety of stimuli. This suggested a simple storage system that held approximately seven items. Later studies demonstrated that memory span could be systematically influenced by a variety of stimulus characteristics, including the type of item. These findings have suggested that the capacity of short-term memory is controlled by verbal processes. INDEPENDENT VARIABLE: the type of material you were asked to recall: digits, letters, or words. DEPENDENT VARIABLE: length of the last list you correctly recalled Your memory span should be highest for digits, slightly lower for letters, and slightly lower again for words. One reason may be that people are more practiced in recalling digits in order (e.g., remembering telephone numbers) than other items. EFFECT: Quite robust

Phonological Similarity Effect

When people are asked to recall a list of items, their performance is usually worse when the items sound similar than when the items sound different. What is most surprising about the phonological similarity effect is that it occurs even when there is no auditory input, such as when you read the items silently to yourself. This result has been seen as suggesting that people recode the information. The phonological loop has two parts: the phonological store and the articulatory control process. The phonological store is a memory store that can retain speech-based (phonological) information for a short period of time. Unless rehearsed, the traces within the store are assumed to fade and decay within about 2 seconds, after which they are no longer usable. The second component is the articulatory control process, which is responsible for two different functions: It translates visual information into a speech-based code and deposits it in the phonological store; and it refreshes a trace in the phonological store, offsetting the decay process. There are two independent variables: whether the letters sounded similar or dissimilar, and whether you were asked to engage in articulatory suppression. The dependent variable is the proportion of letters correctly recalled. When you engage in articulatory suppression, performance should be worse than when you did not, and you should also find no difference in recall of similar and dissimilar letters.