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Eliciting False Memories 1 Running head: FALSE MEMORY RECOGNITION Eliciting False Memories: Recollecting Words Not Presented During Recognition J. Maartyn Wyma Saint Mary’s College of California Eliciting False Memories 2 Abstract The measurement of false memories by recording recognition errors was observed by H. M. Roediger and K. B. McDermott’s (1995) study using semantically related lists of words and distractor words. The current study replicated this experiment design. College students (N=32) studied five sets of 15 words, completing a recognition test after each individual trial. Each recognition trial contained multiple studied words, a few regular distractors, and one critical distractor that was semantically relative to the theme of the words in the presentation trial. Results indicated that though accuracy for studied words was high, false recognition, or recognition error, was just as high for critical distractors. The findings of the current study are compared to Roediger and McDermott’s (1995) study and applied to E. F. Loftus and A. M. Collins’ (1975) Spreading Activation Model. Eliciting False Memories 3 Eliciting False Memories: Recollecting Words Not Presented During Free Recogntion Though memory is often looked to as a reliable source of information that can be counted on, it is very much prone to error. Focus on the inaccuracy of memory can be seen in research done by Bransford and Frank (1971) where subjects were given a list of short sentences all relating/alluding to a common theme (The ants were on the table. The jelly was sweet. The ants ate the Jelly). Upon completion of the presentation trial of these sentences, subjects were asked to recognize what sentences had been read. Among the correct and incorrect choices was a distractor, one sentence that matched the theme of the presented sentences but had not been read prior. If the example sentences above had been presented, a distractor sentence would read, “The ants on the table ate the sweet jelly.” Bransford and Frank found that subjects often recognized this sentence, and often with great confidence, though it had never appeared during presentation. Since the theme and context of the distractor sentence fit previous sentences in terms of semantics, subjects were led to believe that sentence had already been encountered. Another example of a subject’s construction of a false memory due to the context of the situation is Loftus’ (1974) research on eyewitness testimonies. Upon watching a video of a car crash, subjects were asked to return a week later and answer the question of whether or not there had been any broken glass present when the cars made contact. By changing the verb in the sentence from contacted to bumped, collided, or smashed, Loftus successfully demonstrated a change in the subject’s memory of the situation. In this case, for subjects who heard “smashed”, Eliciting False Memories 4 34% recall seeing broken glass, whereas for subjects in the “bumped” condition, only 14% remember seeing broken glass. In reality, there was no broken glass in the video, and false memories had been created to fit the context. In this experiment Loftus demonstrated how memory could be distorted based on context and the situation. Loftus and Collins’ (1975) Spreading Activation Model (SAM) provided a possible explanation for the formation of false memories. According to SAM, an individual’s memory is stored as a network consisting of linking concepts. When a concept, which is depicted as a node in a series of intersecting lines, is activated by thinking, hearing, or seeing, it automatically spreads to other related concepts or themes within the network. Networks contain multitudes of connected concepts arranged in proximity based on relation. For example, hearing the word “fetch” could activate the concept “dog” which could further activate the concept “feed” which could lead to “hungry” which could finally end with “pudding”. The words “dog” and “pudding” generally don’t share an obvious connection, but because of a spreading of activated concepts, the relation is made between the two ideas. The Spreading Activation Model lends an explanation for the results of both Bransford & Frank and Loftus in terms of creating false memories based on context. For Bransford and Frank, subjects were likely to choose the distractor sentence as being familiar because it involved concepts that had been activated previously during the presentation trial. “The ants on the table ate the sweet jelly,” fits the description of all three previously studied sentences (the ants, the table, and the jelly), though it had never been presented to the subjects. Familiarity with the Eliciting False Memories 5 related concepts in the new distractor sentence convinced subjects that these sentences had been seen before. For Loftus, the activation of the word “smashed” excited the concept of broken glass more readily than the word “collided”, therefore indicating that for the subjects, if two cars smashed together, there would be broken glass. Loftus’ theory can also be used to explain the results obtained by Roediger and McDermott (1995), whose work is replicated in the current study. In an attempt to elicit recognition errors, Roediger and McDermott presented six lists of 12 words each to 36 subjects from an undergraduate Human Memory class at Rice University. During the presentation trial, each word was presented alone for 1.5 seconds. Each of the different set of words was related to an individual target word that was not presented during the trial. If sleep was one of the targets, words presented during that trial could be bed, tired, yawn, pillow, etc. After the word presentation trial, the subjects completed a 42-­‐item recognition test. Among the choices in the test, 12 words had been previously studied during the presentation trial, and 30 had previously not been presented. Among these nonstudied words (referred to as lures), six were critical (in that these were the subject of the word sets in the presentation trial; for example, sleep), 12 were completely unrelated to those previously studied (for example, cheese), and 12 were only weakly related (for example, soft) to studied words. The goal of the study, to produce recognition errors, was measured by the number of times the critical word was chosen during recognition, with the idea being that though the word itself had not been presented and studied, it bore enough resemblance to the Eliciting False Memories 6 theme of the word sets to activate an association with the word, making it appear familiar. Recognition, in this case, was described as making a recognition error (choosing a word that had not been previously studied) as opposed to actual accuracy of memory. The results of Roediger and McDermott’s experiment demonstrated that even though actual recognition for studied words was high at 86%, the false recognition of critical lures, the words that had not been presented before, was close behind at 84%. Results indicate that recognition of unrelated lures was only 2% while recognition of weakly related lures was higher at 21%, indicating that subjects were aware that these words had not been presented earlier, and were indeed new. From their experiment, Roediger and McDermott confirmed the idea that false recognition can be induced with the use of critical lures. The subjects in their study selected the critical lures over half the time, claiming it to be familiar. This familiarity with the word could possibly be attributed to the SAM, in that the words in the presentation trials triggered an activation of similar concepts, and repeated activation of the same concept, sleep, for example, created a false memory of having seen the word presented. The following study replicated Roediger and McDermott’s (1995) experiment. It was hypothesized that studied words would receive high recognition, critical lures would elicit the highest percentage of recognition errors, and regular distractors would elicit a low percentage of recognition errors. Eliciting False Memories 7 Method Participants Subjects in the study consisted of 32 undergraduate students enrolled in various general courses from the campus of Saint Mary’s College of California. Materials Word lists. Five sets of 15 words were used for the presentation trials in the experiment. Each set consisted of words relating to a single critical lure, as had been the design in Roediger and McDermott’s (1995) study. As an example, for the critical word sleep, words such as bed, soft, pillow, blanket, and tired were studied. Words were presented on a Dell Desktop (PC) using Microsoft Windows 7 and recording software from Hanover College. Recognition Test. Each recognition test consisted of 18 words. These choices consisted of studied items, regular or unrelated lures, and critical lures. Lures in this experiment are referred to as distractor items. For each of the five presentation trials, there were five individual recognition tests specific to each trial. Participants were instructed to select whatever words were recognized as being previously studied. Procedure Upon arrival, subjects were individually directed to a computer and given verbal and written instructions describing the presentation and recognition task (See Figure 1). Each subject participated in five presentation trials and five recognition trials. Presentation trials consisted of 15 words presented at one word per every two seconds. The words in each trial were suggestive of a theme, in that Eliciting False Memories 8 bed, pillow, and tired were all related to the concept of sleep. Immediately after each presentation trial, subjects were instructed to complete the accompanying recognition test, with the object being to select words recognized as having been studied during the previous trial. Subjects were given 20 seconds to complete this task, and eighteen words were displayed for each test. The first of these word types were previously studied items. These words had appeared during the presentation trial and represented no recognition error, as choosing them would result in an accurate memory. Less than ten of the words in the recognition trial were previously studied words. The second type of words included were the regular distractors. These words had not been previously studied and were not closely associated with the theme of the presentation trial (for example, bus would be a regular distractor if the theme was sleep). Choosing one of these words in the recognition test would result in a measurable recognition error. Out of the 18 word choices, the final type of word included was one critical distractor. This word was closely relatable to the theme of each presentation trial, and displayed a direct connection semantically to the words previously studied. In a presentation of bed, pillow, and tired, the critical distractor item would be sleep. Choosing the one critical distractor would be measurable as a recognition error The variable measured in this study was the amount of recognition errors made by each subject. Recognition errors were defined as the selection of words during the recognition test that had not been previously studied. Incorrect choices were therefore either regular distractors or critical distractors, and both were Eliciting False Memories 9 recorded separately. Upon completion of the five presentation trials and recognition tests, subjects were debriefed, thanked, and dismissed. Results As demonstrated by Roediger and McDermott (1995), accuracy of recognition for studied words was high at 78.26% (see Figure 2). Of the two distractors, the critical distractors, as hypothesized, elicited the highest percentage of recognition errors at 76.77%, while regular distractors were only selected 1.94% of the time (see figure 3). These results support the hypothesis and replicate the results of the initial experiment by Roediger and McDermott (1995). Discussion The results, which matched the hypothesis, indicate that apart from having high recognition accuracy for previously studied words, subjects often recognized words they had not been shown. The high percent of recognition errors for critical distractors as opposed to regular distractors demonstrates that the results were based not on chance but rather on the effectiveness of the critical distractor and its relation to the presented words. If these critical lures had no relation to the words in the trial, the percentage of recognition errors should have been comparable to those of the regular lures, suggesting that the semantic relationship shared between the critical lures and the presentation words elicited a false memory. The pattern of the results mirror those obtained by Roediger and McDermott (1995), where recognition error was at 86% for critical distractors, and 2% for Eliciting False Memories 10 regular distractors. This suggests that not only is this a reliable way to elicit memory errors during a recognition task, but also that false memories are specific to semantically related knowledge and not simply random, unrelated information. In regards to the Spreading Activation Model, the results indicate that the activation of a series of related concepts increases the likelihood of a recognition error when the stimulus is seemingly related to the active concepts. Having seen the words bed, rest, tired, dream, and pillow, the logical conclusion would be that the concept of sleep must also be activated by relation and would therefore appear to be a reasonable choice during a recognition test. Though the word sleep itself had never appeared, the familiarity of the word, attributed to the spreading activation of related concepts, would cause subjects to believe that it had indeed been studied previously, and though Roediger and McDermott didn’t apply SAM directly to their 1995 study, the results obtained then and here seem to support the parameters of the model. The critical distractors received the highest percentage of recognition errors because of similar concept activation by studied words, while the regular distractors were not activated because of a lack of relation, thus substantiating the idea of the Spreading Activation Model. Though Roediger and McDermott suggest that these recognition errors are caused by an activated semantic relation between the critical distractor and the word lists, recent research suggests that the results can be attributed to another cause. Whittlesea, Masson, and Hughes (2005) propose that the recognition errors produced in the study were elicited by the effects of the Discrepancy-­‐Attribution Hypothesis. This theory suggests that familiarity with a situation or stimulus is Eliciting False Memories 11 caused by previous experience, which leads to a heuristic approach when processing the given situation. In relation to the study, Whittlesea, Masson, and Hughes suggest that the emotional influence of surprise at seeing a critical distractor relating closely to presented words promoted the use of the Discrepancy-­‐Attribution heuristic, which created a feeling of familiarity. Thus, the familiarity with the critical distractor and the tendency to select it as being part of the presentation trial is due not to semantic activation but to previous experience matched with emotional influence. Regardless of the cause of memory and recognition errors, the results of the current study match those of Roediger and McDermott (1995), suggesting that though errors cannot be directly attributed to semantic activation, there seems to be a replicable prevalence of false memories. Eliciting False Memories 12 References Bransford, J. D., & Franks, J. J. (1971). The abstraction of linguistic ideas. Cognitive Psychology, 2, 331-­‐350. Loftus, E. F., & Collins, A. M. (1975). A spreading-­‐activation theory of semantic processing. Psychological Review, 82, 407-­‐428 Loftus, E. F., & Palmer, J. C. (1974). Reconstruction of automobile destruction: An example of the interaction between language and memory. Journal of Verbal Learning and Verbal Behavior, 13, 585-­‐589. Roediger, H. L., & McDermott, K. B. (1995). Creating false memories: Remembering words not presented in lists. Journal of Experimental Psychology: Learning, Memory, and Cognition, 21, 803-­‐814. Whittlesea, B. W. A., Masson, M. E. J., & Hughes, A. D. (2005). False memory following rapidly presented lists: The element of surprise. Psychological Research/Psychologische Forschung, 69, 420-­‐430 Eliciting False Memories 13 Figure Caption Figure 1. Written instructions for subjects distributed before presentation trials. Figure 2. Recognition accuracy of previously studied words during the recognition test. Figure 3. Percent of recognition errors of critical distractors and regular distractors during the recognition test. Eliciting False Memories 14 Figure 1. Written instructions for subjects distributed before presentation trials I will set up the parameters for the experiment. When you are ready, please press the space bar to start the experiment. You will get a + above the middle of the computer screen. Then, during the study phase, 15 words will appear, one word per two seconds. You are to study them as best you can. The, during the recognition phase, a grid will appear with a list of words. Your job is to click on the words that were part of your study phase. You will have few to choose from then the 15 you studied. Each time you click a word, it will fade from black to gray to indicate that is the word you want. You will be allowed 20 seconds to try and remember what you studied. After 20 seconds, the grid will disappear indicating that the block has ended and a new block of trials will begin. You are to proceed in the same manner until you have completed five blocks of trials. When you are done with the experiment, STOP! AND DO NOT EXIT THE PREOGRAM. Call me and I will save your data. Eliciting False Memories 15 Figure 2. Percent accuracy of studied words 100 90 Percent Recognition Accuracy 80 78.26 70 60 50 40 30 20 10 0 Studied Words Eliciting False Memories 16 Figure 3. Percent of recognition errors for critical and regular distractors 100 90 Percent Recognition Error 80 76.77% 70 60 50 40 30 20 10 1.94% 0 Critical Distractor Reguar Distractor Distractor Words