How long have I been on autopilot?

Living my life in an auto-navigational blur has probably saved my life. I’ve dampened every process, every thought, every experience along the way. And I’ve experienced some things that I still wouldn’t talk to a psychologist about.

I’m only just figuring out that I’m missing out on actual quality of life. Now, not before. I’m glad I had autopilot before. But now it’s time to heal.

No wonder I’ve blacked out so much. What a strange defense mechanism.

From now on, I’m going to feel the toothbrush on my teeth, see the clothes I choose to wear, taste to appreciate…and I’m going to remember.

Maybe that will make it easier to talk. I’ll have something to remember, to talk about.

Maybe this is what hope feels like.

Memory Encoding and Retrieval with Distractors

The following is a proposal I wrote for an Advanced Cognition lab during my Psychology B.A. No actual ERP/EEG research was completed; all discussed research and anticipated results are based on peer-reviewed literature. Please do not submit any part of this work as your own.

ERP examination of background noise while learning: Repercussions on subsequent episodic memory performance
December 2006

At ______ University, not unlike other academic settings, students are faced with a number of short-lived opportunities and often fall into poor studying habits. A brief observation of the main floor of the campus library demonstrates a social atmosphere that might distract from focus on class material: music, clacking keyboards, and loud conversations among friends discussing their plans for the evening.

Just how destructive this multi-tasking might be to a student’s grades depends on many factors, such as the amount of time these same students spend on the infamous “______ Advantage” laptops, which provide them with constant access to media. To understand how different noise sources affect memory is indeed important practical knowledge, especially true to those who invest heavily in an education; would students weigh their priorities more carefully if it could be shown scientifically and directly that applied focus pays off? The emphasis of the present study therefore is to examine, in an economically-valid laboratory setting, the flexibility and accuracy of students’ episodic memory retrieval based on encoding processes performed with the presence of auditory distractors.

The irrelevant speech effect (ISE) is the impairment of recall when irrelevant auditory material is presented together with the items to be memorized, competing for available processing resources. Numerous studies have demonstrated that white noise has no effect on to-be-remembered information, while nonvocal music shows a moderate ISE, vocal musical shows a greater one, and irrelevant speech (IS) shows the greatest ISE, regardless of the meaningfulness or loudness of the speech (Martin-Loeches, Scheweinberger, & Sommer, 1997; Klatte, Lee, & Hellbruck, 2002; Enmarker, 2004; Norris, Baddeley, & Page, 2004; Kopp, Schroger, & Lipka, 2006). However, meaningful IS is more disruptive than meaningless IS for reading comprehension and proof reading, and it has been shown to cause impairments on attention, as well as episodic and semantic memory (Enmarker, 2004).

Behavioural studies have focused on sorting between competing theories regarding the memory processes which regulate the ISE, of which few will be discussed. Baddeley’s model of working memory (WM) explains this effect through interference in the phonological loop, when irrelevant spoken material competes for attentional resources with the information being intentionally processed (1986, as cited in Martin-Loeches, Schweinberger, & Sommer, 1997; Klatte, Lee, & Hellbruck, 2002). The effect will theoretically be larger when the irrelevant material is phonologically similar to the target items. On the other hand, the changing-state hypothesis, as proposed by Jones in his object-oriented episodic record (O-OER) model, is the most promising theory when it comes to explaining the ISE, according to study results (Martin-Loeches, Schweinberger, & Sommer, 1997; Klatte, Lee, & Hellbruck, 2002). This theory suggests that IS is based on acoustic differences (changing-states) rather than phonological similarity between target and nontarget items (same-state); the higher the phonological variability, the stronger the perceived effect.

Klatte, Lee and Hellbruck (2002) examined the assumption that ISE occurs under the phonological loop model as discussed above, and four experiments were performed. In Experiment 1, participants practiced articulatory suppression (AS) during retention periods, a process in which rehearsal is prevented by the repetition of a word (i.e. “the”). This task is often given to participants by an experimenter because it is believed that visually presented items must be translated into a phonological code by means of subvocal rehearsal; in line with this assumptions are consistent findings that AS abolishes the ISE when items are presented visually, but not when presentation is auditory (Klatte, Lee, & Hellbruck, 2002; Norris, Baddeley, & Page, 2004).

The study design included both visual and auditory presentation, and background sounds (either irrelevant speech or broadband sound, which does not disrupt serial recall performance) were presented continuously. No significant difference was found between the visual and auditory groups, and performance was poorer overall in the IS conditions. In the visual presentation AS condition, the ISE was completely abolished, as was expected; in the auditory presentation AS condition, however, the ISE withstood suppression. This was in line with the assumption that speech gains obligatory access to the phonological store while visually presented verbal material must be translated into phonological code through subvocal rehearsal, which was successfully prevented by AS. The results of Experiment 1 set the basis of the subsequent experiments by confirmed Baddeley’s hypothesis of differential access to the phonological store for heard and read materials; visual material must be articulated in order to become susceptible to IS.

Experiment 2 explored recent findings that heard items can be retained in short-term memory without the help of serial recall for at least 10 seconds. The authors therefore predicted an ISE after a retention interval which exceeded the duration of the phonological trace originally postulated by Baddeley. Their results indeed contradicted the assumption of rapid temporal decay of phonological traces without rehearsal for auditory presentation, as the ISE remained even with AS and a longer retention interval.

Their results contradicted the idea that phonological traces decay rapidly when AS is used to prevent rehearsal. Experiment 3 was virtually identical and served mainly to confirm the findings of Experiment 2.

Finally, in Experiment 4, visual presentation was used and AS was confined to the retention interval as opposed to throughout the entire task. Participants were therefore free to rehearse during presentation of the stimuli. According to the phonological loop model, the ISE should withstand the suppression because rehearsal was permitted; the results showed that the ISE was able to survive a 10-second retention interval filled with AS, which seems to suggest that there is a long-enduring phonological trace which can be maintained for longer periods than initially imagined.

Overall, Klatte, Lee, and Hellbruck’s findings are in line with the assumption that auditory material gains direct access into the phonological store while visual stimuli must first be translated; however, they contradict the standard phonological loop model by demonstrating phonological traces which exist beyond a 10-second filled interval that does not allow rehearsal for maintenance. Suppression during presentation of the stimuli did abolish the ISE, but left it unaffected when initial processing occurred without suppression and with the distraction of irrelevant background noise. Their explanation for these events included the straightforward notion that competing auditory input leaves less capacity for effective rehearsal of learned material. The changing-state effect was also found in the study, where sequences of different syllables produced more disruption in memory than repetitions of single syllables, which contradicts Baddeley’s model.

Enmarker (2004) studied the effects of meaningful IS and road traffic noise on attention, episodic memory, and semantic memory in teachers and students. Their interest was based on findings that background noise causes detrimental influences on long-term memory performance and attention in children and young adults. A literature review led to the assumption that difficult tasks would suffer more from noise exposure (especially when it is unpredictable) because it is assumed that attentional resources are allocated toward the distraction, leaving less processing ability for the task at hand. This should be especially true when the concurrent cognitive processes utilize the same type of processing. Enmarker therefore hypothesized that verbal episodic memory should be impaired by meaningful IS more so than road traffic noise, though the competing auditory input would still lead traffic noise to impair attention.

It was also hypothesized that, because recognition tasks provide more environmental cues about items than recall tasks, the difficulty of the retrieval task should be based at least in part on availability of retrieval cues as well as how well the information was encoded; in other words, performance on recognition tasks was still expected to be impaired, but less so than in recall tasks.

Age-dependent factors were also considered in Enmarker’s study, because it is possible that, if memory ability plays a role in efficient processing, memory performance becomes more susceptible to noise interference as a person ages. Teachers were chosen as the main subjects in order to achieve a matched group in terms of education, while maintaining a subject base known for exposure to a demanding sound environment. The teachers were assigned to one of three independent groups in which they were exposed to either meaningful IS, road traffic noise, or silence. Conditions were carefully controlled so that noise assignment during encoding was the only true variable; for instance, each participant was run through at the same time of day, in a climate chamber with controlled air temperature and light level. Furthermore, in order to prevent semantic knowledge from confounding the results, the text read by participants had all real names and words replaced by imaginary ones. Text comprehension was then tested with 8 cued recall question and 12 multiple choice recognition questions; demographic variables were also collected, as well as questions concerning hearing and health status, and ratings about perceived effort used and degree of difficulty of the text.

Enmarker’s findings were that students aged 18-20 years outperformed both young and old teachers alike, which led to the proposal that episodic memory probably has its peak in early adulthood, maybe around 20-25 years. However, there was no interaction between age and noise, contrary to expectations; this was incompatible with the assumption that memory performance declines when attention is divided at the time of encoding relative to conditions of full attention. In line with the prediction, meaningful IS and road traffic both impaired cued recall of the text; the relative impact of the two noise sources did not differ for this task, likely because both of these had similar levels of acoustic variation. However, road traffic noise did not impair the recognition task whereas the meaningful IS did (though less so than in the recall task). There were no significant differences in the ratings of perceived difficulty of the text or effort used between the groups; hearing, attention, affect and annoyance did not mediate these noise effects. Enmarker concluded that, in order to develop a more elaborated understanding of noise impact on memory systems and attention, research must examine semantic content and acoustic variation independently.

Norris, Baddeley, and Page (2004) performed five experiments to examine the retroactive effects of IS on recall from short-term memory (STM). They also explored the assumption, recently challenged, that IS has the same effect on memory as AS, based on the fact that both impair recall by setting up competing streams in memory. Following a theoretical review they proposed that there may be no need for simultaneous presentation of IS with to-be-remembered items to achieve the ISE; this would once again be inconsistent with theories that predict the absence of an ISE when rehearsal is prevented. Previous findings provide evidence that IS presented before a list has no effect, while there is a significant effect of IS presented during the second half of a list or subsequently (during a retention period). Therefore, the authors concentrated on the conditions under which each of the models of STM (WM, O-OER, the feature model, and temporal distinctiveness theory or TDT) predicts retroactive effects of IS.

All conditions in Norris, Baddeley and Page’s experiments were designed to minimize the possibility of rehearsal, based on broad research concerning the processing times necessary in order for all desired effects to be achieved. In Experiment 1, the IS (excerpts of speech in a foreign language) was presented over headphones during the retention interval between presented lists and recall tasks; an arithmetic task prevented rehearsal. This avoidance of rehearsal was promoted as much as possible: participants were informed that recall tests would not be graded unless the simple arithmetic problem was done correctly.

As expected, it was found that performance was reliably better under conditions with no IS; the effect of interest was also found, when performance did not reliably differ between conditions in which IS was presented simultaneous to the list and those in which IS was presented after the list, during the retention period. Both of these conditions reliably differed from the condition in which IS was presented throughout the entire trial. Experiments 2-5 built on these results by attempting to demonstrate similar results with an overt task (digit-reading) rather than covert task (such as the standard procedure, AS) to prevent rehearsal.

In Experiment 2, the authors examined the common belief that the phonological store decays after a period of 3-6 seconds. Even after longer delays were used, a reliable retroactive IS effect was still produced. This suggests either that the phonological loop is not the locus of the ISE, or that IS affects an alternative system that short-term information is transferred to after longer delays. This experiment demonstrated that the ISE could be detected after as many as 12 seconds.

Experiment 3 had the same results as the prior when IS was presented simultaneous with list presentation, and retention length was added as a condition. It was thought that a short retention period would encourage use of the phonological loop, while a longer interval might make use of the proposed alternative short-term phonological store; participants were unaware of the length of the upcoming retention interval to avoid rehearsal style becoming a confound, if rehearsal was able to be used at all. It was noted that, when measured as a proportion of the number of errors at each retention interval, the ISE was greater for the shorter intervals, which suggests that the phonological loop does play a reliable role.

Experiment 4 directly address the question of whether the long-lasting effect of IS was contingent on the stimulus list having been in the phonological store at some point. AS during list presentation would prevent the visual information from being translated into the phonological store, which would force participants to rely on some alternative store; if IS influences this alternative store directly, a retroactive ISE should still be observed. The results confirmed that the ISE does depend on the information having first been encoded in the phonological store, though it does not necessarily need to be retrieved from it; in other words, whatever alternative store supports the delayed retroactive effects of IS does not seem to be sensitive to the presence of IS.

Experiment 5 served to push participants to their performance limits by using a more demanding digit-reading task and a shorter stimulus presentation period, in order to minimize the possibilities of rehearsal. This final experiment simply provided further confirmation of a retroactive IS effect. Overall, Norris, Baddeley, and Page were able to demonstrate that IS has retroactive effects on material already in memory in 4 of their 5 experiments. They were able to infer that rehearsal was not a factor based on consistently poor results in performance after a filled retention period of 9 seconds; they also based this assumption on the fact that, when asked, no participants reported being able to rehearse the list in Experiment 5. We can conclude from this study that the ISE is not mediated by its influence on rehearsal, and that it only emerges when items are first encoded into the phonological store.

Neuroimaging studies on the ISE have been scarce; Martin-Loeches, Schweinberger, & Sommer (1997) claim to be the first ERP study to directly manipulate IS. They proposed that the effect of an experimental manipulation on the ERP can be directly measured as a “difference wave,” subtracting the ERP obtained under a condition in which the experimental effect in question is absent or small from the ERP recorded when it is present. This procedure eliminates the activity of elements equally involved in both conditions, leaving the effects or activity produced by the experimental manipulation. Participants (N = 12, M = 26 years) with no neurological or hearing complaints completed the experiment in a sound-attenuated chamber. They were provided with a fixation point in order to minimize eye movements (which would cause recording artifacts) and a chinrest in order to stabilize head position. Furthermore, since rehearsal was allowed, they were asked to reduce movements of the mouth and tongue as much as possible and encouraged to use covert rehearsal methods. They were given instructions in writing as a standardization procedure. Presentation of stimuli and IS were auditory; subjects were advised to attend to the male voice (target) and ignore the female voice (nontarget or IS). Memorization should be achieved in order of presentation.

Only the results concerning Condition 2-1 are of interest to the present study, as this was the condition that introduced irrelevant speech. Subjects in this condition showed a long-lasting activity with positive values over frontal electrodes, and negative values over posterior and occipital electrodes (all were bilaterally distributed). Significant condition effects were present for the time windows between 200 and 700 msec, while the long-lasting activity of IS alone was most reliable in the 200- to 300-msec window. IS was also associated with a significant increase of error rates. Martin-Loeches, Schweinberger, and Sommer stated that their data suggest that the ISE is based on phonological variability within the irrelevant stream more than on phonological similarity between relevant and irrelevant material; however, it does appear from conditions involving phonological similarity that phonologically similar material requires more processing than does dissimilar material, increasing processing demands. Overall, these findings are consistent with the changing-state hypothesis and once again contradict the phonological loop model.

Finally, Kopp, Schroger, and Lipka (2006) used EEG to further investigate the effects of IS. Their literature review pinpointed certain structures that are related to short-term rehearsal: the premotor cortex, supplementary motor cortex, left prefrontal cortex, and cerebellar regions. Older PET studies have associated some neural structures that are involved in the ISE specifically; these studies showed distributed suppression of components of the verbal working memory network, particularly in left frontal and temporal brain regions. However, these PET studies and other imaging methods are limited when it comes to temporal dynamics of neural activity; this leads to an incomplete picture when it comes to memory processes, as oscillatory activity (particularly of the theta and gamma rhythms) are shown to be closely related to encoding, rehearsal and retrieval. Initial evidence was found that the neural basis of the ISE is the reduction of long-lasting synchronization of gamma activity in the underlying phonological rehearsal network; this study aimed to find these patterns under conditions of spoken and written recall. The authors predicted a reduction of gamma synchronization at left fronto-central sites from quiet to IS in the spoken conditions.

Participants of Kopp, Schroger, and Lipka’s study (N = 21, aged 18-32) all had normal or corrected-to-normal vision, and baseline working memory capacity was measured before the experiment through a digit span task. Word lists were matched in word frequency and semantic relatedness, and the trials were designed in a way that prevented participants from establishing elaborated rehearsal strategies. Participants were interviewed after the experiment about their rehearsal strategies, and subjective ratings on task difficulty were collected. All participants reported using a phonological strategy, and stated that any attempts at more complex strategies were given up during the practice trials when the item presentation rate proved too fast; in other words, attempts to prevent elaborated rehearsal strategies were successful. A main effect was found for distraction, F(1,20) = 26.3, p < 0.001, with a pronounced decline of performance in speech compared to quiet conditions. Gamma coherence did in fact decrease at central and left-frontal electrode combinations during the retention interval in the spoken recall condition; with written recall, however, no decrease was found from quiet to IS conditions.

It was proposed that an effect was found in spoken recall because articulating the first few items may have interfered with the remaining items in STM. Kopp, Schroger, and Lipka (2006) concluded that a possible future direction of distraction by IS is to explore its interaction with recall mode. Randomized spoken and written recall would have an effect on rehearsal methods since participants would not be able to anticipate the most efficient method.

As the theoretical explanations for the ISE are narrowed down and the mechanics of its processes are clarified, it becomes more appropriate to examine specific effects and interactions within the STM paradigm. Because the focus of the present study is on how IS affects learning in students, the information gained from behavioural and neuroimaging studies will be applied or adapted to a study which imitates student life as carefully as possible while experimentally controlling for extraneous variables. The conditions of interest in this study are presentation modality (visual, which would mimic independent study; and auditory, which resembles lecture-style learning), distraction (white noise, vocal music, and meaningful IS), and test type (recognition and recall). The design will employ intentional learning and allow covert rehearsal (covert in order to avoid movement artifacts), because students are aware that they will be tested in an academic setting. Finally, because it has been shown that simultaneous IS and IS during a retention interval do not differ significant, IS in this study will be continuous (presented throughout both text presentation and the interval).

The present study could have strong theoretical implications for the understanding of memory and attentional resources, but it would also be of significance to students who may not know how to make the most efficient use of their study time. Divided attention has shown a larger detrimental effect during encoding than during retrieval; therefore, emphasis in noise research has been on the encoding phase rather than on retrieval (Enmarker, 2004), and thus all memory tasks in this study will be performed in silence.

Hypotheses will be based on two main assumptions: first, that the difficulty of the retrieval task is affected by how well the information has been encoded, and also on the availability of retrieval cues (Enmarker, 2004); secondly, that the quality of encoding is affected by how large resources could be allocated to the task, as a result of resource competition and availability. It is hypothesized that participants in the white noise condition will show more activity in the brain areas associated with short-term rehearsal: the premotor cortex, supplementary motor cortex, left prefrontal cortex, and cerebellar regions. Subsequent memory for participants in the noise conditions (exposed to vocal music or meaningful IS) is expected to show increased negativity in the brain regions previously linked to the ISE (particularly in left frontal and temporal brain regions), which would support the idea that these memories were not as deeply encoded therefore still register as fairly unfamiliar to the brain. It is also expected that participants in the noise conditions will only be able to express learned information in a limited manner; recall task accuracy will be significantly lower for the music and IS groups than for participants in the white noise condition. It is expected that there will be little discrepancy between the three groups in terms of recognition task accuracy, with the IS condition reflecting the worst performance.

Method

Participants

Participants (N = 16, 18-24 years of age) will be ______ University Psychology students in their third or fourth year of study in order to match participants for education level and estimate baseline intelligence. They will be right-handed, monolingual, and native speakers of English. They will be screened for problematic neurological histories, and all will have normal or corrected-to-normal vision and hearing. Participants will be paid or receive course credit in exchange for participation.

Measures

Instructions will be given in writing in order to standardize the procedure. Stimuli will consist of one practice paragraph and three true paragraphs adapted from a history textbook, with all real words and names replaced by imaginary ones to prevent semantic memory activation. Each paragraph will be composed of four sentences, all matched in length and overall approximate time-to-read (approximately one minute). Stimuli will be divided into three trials, and a partial Latin square will balance text order and distraction order so that each level appears once per participant, as well as memory test type order (either recall or recognition will appear twice for each participant). Ratings of perceived effort used and perceived test difficulty will be collected from participants after each trial. Demographic variables and GPA will also be collected in order to provide information regarding background similarities between participants and individual rough baseline intelligence levels; this information will not be analyzed and will remain confidential.

The experiment will be conducted in a sound-attenuated chamber, with both light level and temperature (21°C) controlled. Subjects will be wearing headphones, and will be seated 2 feet from a 19” laptop monitor and keyboard, with a chinrest to stabilize head position. In the visual presentation condition (N = 8), sentences will be presented on the monitor one word at a time to avoid excessive eye movements and recording artifacts, and the beginning and conclusion of sentences will be signaled with a fixation point, which will remain on screen for 100 msec after the participant pushes a key. Subjects will control the presentation rate by hitting the J key (allows them to move forward by a word) or the F key (allows them to move forward by an entire sentence); the paragraph is looped, so once the last sentence is complete, the first sentence reappears. In the auditory presentation condition (N = 8), the participant will not have the same control because a student would not be able to replay a lecture. The target file will be played slowly once over headphones in a male voice.

In both conditions, the distraction condition (nontargets) will be played over headphones; participants will be told to ignore these during the trials. White noise of constant amplitude will be played for the no-distractor condition. A popular “Top 20” song, rated in terms of lyrical content and acoustic variability, will be pulled from the radio for the vocal music condition, as this would best represent the type of music that the majority of students would listen to in their own time. The IS condition will be composed of excerpts of meaningful speech in a female voice; this will alternate with the male target speech in the headphones so that it is heard equally from each earpiece. All three conditions will be matched for frequency and loudness.

The recognition and recall memory tests will be presented on the monitor upon the completion of each trial. They will be randomized so that participants do not anticipate question type and rehearse accordingly. Recognition memory tests will appear in the form of a multiple choice question; first, the question will appear, and the participant presses any key to view each possible answer individually before they must make their response (one out of four possible answers is correct). Responses are made by selecting the screen that displays the correct answer and hitting the Enter button. The cued recall memory task is in the form of fill-in-the-blank questions, also presented one at a time. The participant must type in the appropriate word as a response; they may move among questions and return to enter a response at a later time. Both recognition and recall test questions come in groupings of three for their respective trials.

The ERP recording will be recorded from 64 sites on the scalp. The electrooculogram (OEG) will also be obtained. In order to measure tongue and mouth movements, an additional electrode will be located in the position most sensitive to subvocal articulation, which will be determined during the practice trial to accustom participants to the EEG equipment. Each epoch will begin 100 msec prior to target onset (it will begin when the subject presses a key at any fixation point in between sentences), and will end upon the appearance of the next fixation point. A baseline will be calculated by averaging the pretarget recordings, and the ERP will be digitally filtered from .1-20Hz to reduce noise. Ocular artifacts will be corrected, and trials with uncorrectable EOG artifacts or other facial activity (+/- 75mV) will be excluded from analysis. Finally, the signal will be averaged for each condition to increase the signal-to-noise ratio, at approximately 40 trials per condition. The dependent measures to be analyzed are the amplitude of the component and the latency of the component; the independent measures are distraction (3 levels), presentation modality (2 levels), and test type (2 levels).

Procedure

Participants will be randomly assigned to either the visual or auditory presentation modality before they arrive to be tested individually in the study. Upon arrival, they will receive a standardized instruction sheet explaining the aim of the study and what they are expected to do over the course of the EEG recordings. Once informed consent has been attained, facial areas will be cleaned in preparation for the electrode cap. The cap will take approximately 15 minutes to set up, during which time the participants will be permitted and encouraged to review the instruction sheet. Upon completion of the set-up, a short practice trial will familiarize the participant with the task demands and finalize appropriate facial electrode locations. The experiment will not proceed until the participant fully understands the instructions.

Depending on presentation modality, participants will either notify the experimenter when they are prepared to hear the first trial (the auditory condition), or push any key to proceed from the fixation point to the first trial (the visual condition). Participants in the visual trial will be given three minutes to review the paragraph, while the run time for the auditory presentation will take approximately one minute (the same as the estimated time-to-read each paragraph in the visual condition). A retention period of 10 seconds will follow the end of target presentation. Participants in the noise conditions will hear this continuously from the initial target onset (the first sentence) until the end of the retention period. On the monitor, a 3-2-1 countdown of the last three seconds of the retention period will notify the participant that the test is about to begin.

Both the recognition and recall tests are only three questions long, and since the ISE is fairly short-lived, only a minute will be provided to complete the test. Blank answers will be scored as incorrect. All recall tests will be reviewed for spelling errors in case the program scores these as incorrect. Each trial will therefore take from 2-5 minutes.

Upon completion of the final trial, participants will be unhooked from the EEG and the predictions of the researcher, as well as previous results, will be described. A debriefing sheet will be provided, and the opportunity to be contacted with the results upon completion of analyses will be offered to the participant. Overall, each individual session should take no more than 50 minutes.

Results

A 3×2 repeated measures ANOVA will be performed on the data from the visual presentation condition (see Figure 1). It is expected that performance on memory tasks will show a significant main effect of Distraction, with the white noise condition demonstrating the highest response accuracy overall and the IS condition demonstrating the lowest accuracy, with the music condition close behind IS. It is also expected that a significant main effect for Test Type will demonstrate that memory performance in recognition tasks is superior to performance in recall tasks. Furthermore, a Distraction x Test Type interaction is expected; t-tests will demonstrate that, while performance from recognition to recall tasks decreases for both music and IS conditions, there will be not be a significant difference between recognition and recall test results in the white noise condition.

A 3×2 repeated measures ANOVA will also be performed on the data from the auditory presentation condition (see Figure 2). Identical results to the above are expected, with greater discrepancies between the white noise and IS conditions due to the fact that cognitive processes are now competing for the same resources.

ERP recordings will demonstrate general increased negativity over brain areas associated with STM and verbal working memory.

Importance of Anticipated Results

ERP examinations of the ISE have barely made their way into the literature; this report supports recent behavioural literature while integrating neuroimaging data that may eventually help us understand not only how, but where in the brain and why these effects occur in memory processes. While the temporal advantages of EEG make ERPs worthwhile, future studies may focus on using the modern imaging technique of fMRI to locate the areas of increased and decreased activation associated with IS. This could better narrow the search, so to speak; otherwise, analyses of the huge amounts of data provided by ERP studies are not much better than fishing in the brain.

References

Enmarker, I. (2004). The effects of meaningful irrelevant speech and road traffic noise on teachers’ attention, episodic and semantic memory. Scandinavian Journal of Psychology, 45(5), 393-405.

Klatte, M., Lee, N. & Hellbruck, J. (2002). Effects of irrelevant speech and articulatory suppression on serial recall of heard and read materials. Psychologische Beitrage, 44(2), 166-186.

Kopp, F., Schroger, E., & Lipka, S. (2006). Synchronized brain activity during rehearsal and short-term memory disruption by irrelevant speech is affected by recall mode. International Journal of Psychophysiology, 61, 188-203.

Martin-Loeches, M., Schweinberger, S.R., & Sommer, W. (1997). The phonological loop model of working memory: An ERP study of irrelevant speech and phonological similarity effects. Memory & Cognition, 25(4), 471-483.

Norris, D., Baddeley, A.D. & Page, M.P.A. (2004). Retroactive effects of irrelevant speech on serial recall from short-term memory. Journal of Experimental Psychology: Learning, Memory, and Cognition, 30(5), 1093-1105.

Figure 1: Anticipated results

Figure 2: Anticipated Results

Nature of Memory Retrieval

The following is a paper I wrote for an advanced Cognition class during my Psychology B.A. Please do not submit this paper as your own work.

Qualitative nature of encoding and memory retrieval: Levels of processing
November 2006

Abstract

The current study examines the effects of level of processing on subsequent memory recognition and recall. Undergraduate students (N = 13) participated in a classroom task to test memory for stimuli processed according to case, rhyme or semantics. They made judgments concerning whether a target word was an appropriate response to a previously viewed question, and filled out first a recall then a recognition test. It was hypothesized that, for both tests, memory for words in the semantic condition would be greatest, followed by those in the rhyme condition and finally those in the case condition. Two Repeated Measures ANOVAs found main effects for question type, and Paired t-tests supported the hypotheses by demonstrating the predicted relationships.

Levels of Processing

Memory has been an area of intense research focus for decades because it plays a role in just about everything we do, though it tends to go unnoticed until a failure occurs. Numerous processes (mainly attention, encoding, rehearsal and retrieval) must be studied in order to achieve even a basic understanding of the complexity of memory. The question of levels of processing, which concerns encoding and retrieval processes, is important because it could have extensive theoretical and educational implications. Some relevant findings have included the idea that it is the operations carried out on material that determine retention, rather than a simple intention to learn (though attention is of course necessary). Also, different encoding operations are important to different retrieval conditions, a finding which presents the factor of context into learning processes. Knowledge about these mechanisms could change the way teachers present difficult material for the first time, or the way students prepare for an upcoming final. To understand the basic operations of learning and memory would indeed have significant implications in our school systems.

Many theorists have attempted to explain the process of remembering based on a model of the constituents of memory discussed above. Craik and Lockhart (1972) presented the depth of processing view of memory, focusing on encoding operations themselves. They claimed that a memory trace is the record resulting from the perceptual and cognitive analyses carried out on the stimulus. Preliminary stages of perception concern physical or sensory features, whereas the later stages are more concerned with matching the input against past learning to extract meaning; therefore, greater depth implies a greater degree of semantic analysis (meaningful events are better retained due to deeper processing). It was also argued that memory trace may be less or more elaborate and durable depending on the number and qualitative nature of the perceptual analyses carried out on the stimulus, as well as the degree of attention and time devoted to analyzing the stimulus (deeper processing is assumed to require more time, unless the material is of high familiarity or frequency). Craik and Lockhart concluded from their review that an important goal of future research would be to specify the memorial consequences of various types of perceptual operations.

Schulman (1974) used an incidental learning task to determine whether subjects’ semantic judgments about congruity (the appropriate use of a word) led to memorial discrepancies due to differences in processing. Consistent results across the conditions of his study led to what is called the principle of congruity: congruous queries about words yield better memory for the words than incongruous queries. He also found that when false alarms occurred in a recall test, the intrusions were most often semantically related to the word to be recalled; this is evidence that conceptual storage processes are widely involved in encoding. Schulman’s concluding argument was that the words of an incongruous query are encoded as unconnected semantic units, while the words of a congruous query are relationally encoded.

Craik and Tulving (1975) claimed that it is the qualitative nature of the encoding achieved that is important for memory; they concurred with past findings that semantic processing is superior to structural processing. They performed ten experiments within the levels of processing framework proposed by Craik and Lockhart (1972), examining the plausibility of basic notions of the framework, in order to rule out alternative explanations. They attempted to achieve a better characterization of depth of processing while continuing to critically question the model. Subjects were induced to process words on different levels by answering questions that required judgments about typescript, rhyme, or categorization, and then taking part in either a recognition or recall test (which was unexpected in most cases). Time to make decisions was also measured to see if it was correlated with depth of processing. Craik and Tulving found that, consistent with previous findings, deeper encodings took longer to process on average, and there were two significant predictors of high levels of performance on a subsequent memory test: deeper levels of encoding and congruity, as established by Schulman (1974).

The present study is based on Craik and Tulving’s (1975) Experiment 9, in which an intentional learning condition tested the raw occurrence of observable depth of processing effects. Based on prior studies, it is hypothesized that participants will show greater memory traces for words encoded through semantic judgments than those based on phonology (rhyme); furthermore, memory for words encoded through phonological judgments will be superior to memory for words processed orthographically (case). It is also expected that recognition tests will yield better memory than recall tests due to context effects.

Method

Participants

Participants were members of the _____ University community (N = 13); most were students (age range 19-21). Six students participated out of a third year Cognition lab in order to provide their own data for analysis. These students then each conducted the experiment on a peer (age range 17-22) to provide additional data for the study.

Materials

A Microsoft Office PowerPoint presentation was used to display the stimuli. There were 48 trials presented, in question-answer format. Each question remained on screen for five seconds, followed by a word for one second. The next question appeared after five seconds to allow for response time. Each trial led to one of three encoding types: a case judgment (“S1: Is the word in capital letters? S2: flour”), a rhyme judgment (“S1: Does ______ rhyme with each? S2: SPEECH”) or a semantic judgment (“S1: Is a _____ a type of weapon? S2: knife”). Target stimuli were counterbalanced in terms of question type, case (half of the words were written in uppercase), and congruity (half of the words were congruous, or ‘yes’ judgments). All participants made decisions about the same sequence of words.

Three separate forms were used to collect data for the memory tasks. The first was used during the initial presentation of the stimuli to aid in the encoding process and attain accuracy values, to ensure the participant understood directions (see Appendix A). The second was a recall test, in which 48 spaces to recall words seen were provided (see Appendix B). The third handout was a recognition test with 132 items, 48 of which were old words (see Appendix C). The recognition task was presented last so not to confound the recall results.

Procedure

Participants were informed that the purpose of the experiment was to examine an element of memory. They were instructed that, if the target word shown was an appropriate answer to the question posed, the participant should circle ‘yes’ on the sheet provided to them; otherwise, they should circle ‘no’. They would be given five seconds to make that decision before the next question was presented. Participants were also requested not to write any words down during the course of the experiment, as they would be given a series of memory tasks following the completion of the trials.

Once participants had been fully instructed, the decision forms were distributed and the PowerPoint presentation began. Upon completion of the trials, the forms were set aside (but not yet collected). Participants were instructed that they would have ten minutes to complete a recall test, and these forms were distributed; upon completion, they were set aside with those from the encoding process. Participants were instructed that the final task was a recognition test, and that they would again be given ten minutes to complete it. They were to circle exactly 48 words from the list given that they believed had been shown during the initial PowerPoint presentation. At the end of this ten-minute period, all participants inserted their question response and recall sheets into the centre of the recognition test sheets, and the bundles were collected by the experimenters.

Results

All data were analyzed in SPSS (see Appendix D for full output). A 1×3 Repeated Measures Analysis of Variance on the recognition test results found a significant effect of question type, F(2,24) = 19.25, p > 0.001, where proportion recognition of words in the semantics condition was highest (M = .807, SD = .12), followed by the rhyme condition (M = .625, SD = .16), and finally the case condition (M = .462, SD = .14). A second 1×3 Repeated Measures ANOVA on the recall test results also found a significant effect of question type, F(2,24) = 55.69, p > 0.001, with the same general pattern: words in the semantic condition were more often recalled (M = .327, SD = .11), followed by the rhyme condition (M = .125, SD = .08), and finally the case condition (M = .091, SD = .08). When recognition and recall standard error means were plotted, it was apparent that participants had better memory for words in the recognition task (see Figure 1).

Paired sample t-tests were conducted on both recognition and recall data. A significant t-value was found between case recognition and rhyme recognition, t(12) = -2.67, p < 0.05. The comparison between rhyme recognition and semantic recognition was also significant at t(12) = -3.29, p < 0.01. In the recall condition, only the comparison between rhyme and semantics was significant at t(12) = -12.57, p < 0.001.

Discussion

Results supported the hypotheses and were consistent with Craik and Tulving’s (1975) results. An effect of question type was found in both recognition and recall conditions, with semantic encoding trials consistently resulting in the highest mean proportion of remembered words, and those processed at a structural level associated with the worst memory performance. Recognition memory was superior overall to recall memory. In other words, participants were highly successful remembering words that they had processed in terms of category or concept when they had to pick it out of a list of words; their performance was poor, however, in the case where a word was processed structurally (according to case) and they were required to name it in free recall.

The results of this study have implications in education and theories of information processing. The more we understand about the way we learn, the more we can apply this knowledge to everyday behaviour. There were some limitations in the present study, however. It is possible that there was a time confound, since the recognition test occurred later in time than the recall test; perhaps memory traces for words would have been stronger had at least ten minutes not occurred since the initial presentation of the stimuli. Another confound could have been the fact that this study used intentional learning conditions; the experimenter loses some control in the sense that the participant is instructed to learn and may use an unknown coding strategy. However, because the stimuli were presented in close temporal proximity, any efforts at maintenance rehearsal would have likely been disrupted by competing tasks of working memory. Because the participant had to attend to judgments about the next word at a regular interval, this decreases the likelihood of the intentional learning approach becoming problematic. With regards to the results’ implications in education, an intentional learning task would have more economic validity because students learn with the assumption that they will be tested.

Future studies should attempt to replicate these results with a greater number of participants in a between-subjects fashion, with participants either completing the recognition or the recall test; this could increase the power if indeed the extra time between the initial stimulus presentation and the subsequent recognition test was a limiting factor in the present study.

References

Craik, F.I.M. & Lockhart, R.S. (1972). Levels of processing: A framework for memory research. Journal of Verbal Learning and Verbal Behavior, 11, 671-684.

Craik, F.I.M. & Tulving, E. (1975). Depth of processing and the retention of words in episodic memory. Journal of Experimental Psychology: General, 104(3), 268-294.

Schulman, A.I. (1974). Memory for words recently classified. Memory & Cognition, 2, 47-52.

I Thought I Wanted This

Any friend who has seen me through heartbreak has heard me wish I could have the painful memories erased (though I wasn’t a fan of Eternal Sunshine of the Spotless Mind). So why is it just a little scary that this possibility may be on the horizon?

Scientists from the Medical College of Georgia in Augusta and the East ChinaNormal University in Shanghai selectively removed a shocking memory from a mouse’s brain, the team reports in the Oct. 23 Neuron.

Insight from such experiments may one day lead to therapies that can erase traumatic memories for people suffering from post-traumatic stress disorder, or wipe clean drug-associated cues that lead addicts to relapse. (via Science News.)

Yes, I understand the positive applications of such knowledge…but there are SO many worse consequences and vulnerabilities than we can begin to imagine. I guess it’s worthwhile to ponder an option you don’t have just for the fun of it; the reality of brain tampering, however, is making me consider perhaps the more Darwinian approach of letting my less pleasant experiences teach me a thing or two.

UPDATE: I like this article on similar findings a lot better, and not only because of this quote:

Tsien, however, cautions against applying his team’s results to expunging thoughts of broken hearts or limbs. “All memories, even very painful emotional memories, have their purposes. We learn from those experiences to avoid making the same kind of mistake.”