Directed Forgetting of Real-Life Events in School-Age Children

In the present study, participants from 1st, 3rd, and 5th grade completed two simple science activities. A researcher instructed each participant to remember one of the activities and forget the other. Children’s memory for both activities was assessed after a two-week delay. Data analyses yielded a slight age-related increase in directed forgetting (DF) of the two activities, but overall levels of DF were low. In contrast, the trend for word list DF established in the literature was replicated. This pattern of results is interpreted as a reflection of the context sensitivity of cognitive processes in children.

Introduction

Directed forgetting is impaired memory following an instruction to forget certain information. In adults, directed forgetting has been reliably produced in numerous laboratory experiments (e.g., Sahakyan & Goodmon, 2007; Sheard & MacLeod, 2005; Sahakyan & Kelley, 2002). Developmental research has shown that directed forgetting increases with age. Harnishfeger and Pope (1996), for example, instructed groups of 1st, 3rd, and 5th graders and college students to remember a set of words for a later recall test. After the first ten words of a 20-item list had been presented, however, the experimenter informed the participant that the words presented thus far had been for practice only, and that they should forget them and focus on the next set of words instead. When comparing recall of words from the to-be-remembered (TBR) and to-be-forgotten (TBF) lists, 1st graders showed low levels of directed forgetting (2.50 TBR versus 1.25 TBF words, on average), compared to 3rd graders (3.13 versus 1.75), 5th graders (2.71 versus .86), and especially college students (6.25 versus 2.50).

Harnishfeger and Pope (1996) and others (e.g., Bjorklund & Harnishfeger, 1990) attribute directed forgetting effects to cognitive inhibition, or the ability to suppress previously activated cognitive components or processes. The argument for cognitive inhibition is that before the forget cue is issued participants encode all of the presented items from the TBF list. Any directed forgetting effect would therefore presumably rely not on encoding, but on retrieval processes, such as retrieval inhibition during the recall phase (e.g., Anderson, 2005). Many contemporary cognitive theories postulate that keeping irrelevant information out of working memory is an important part of efficient cognition (e.g., Wilson & Kipp, 1998). In fact, some theories propose that more overarching developmental improvements in memory and cognition are largely the product of increasingly efficient inhibition (e.g. Bjorklund & Harnishfeger, 1990). Cognitive inhibition has been closely linked to frontal lobe maturation, which occurs largely throughout the elementary school years (Dempster, 1993).

Although cognitive inhibition might well be responsible for directed forgetting, alternative explanations do exist. In fact, the debate over the mechanism(s) of directed forgetting has a long tradition (e.g., Bjork, 1972; Weiner, 1968 in Sheard & MacLeod, 2005). To some extent, which mechanism appears to be most likely is linked to the methodology used to test directed forgetting. Lehman, McKinley-Pace, Wilson, Slavsky, and Woodson (1997), for example, used an item-by-item directed forgetting task in which participants are given either a remember- or a forget-cue immediately after each individual word. The 3rd and 4th graders and college students in Lehman et al.’s study were told a story about a bee who needed to find honey to save his hive. They were asked to help remember those places where the bee found honey, but to forget the ones where he did not. Each “place” was represented by a word on a note card (e.g., tree), and was immediately followed by either a picture of a honey pot (remember cue) or a red X (forget cue) was shown (adults were shown a green circle or red X). Directed forgetting was assessed using both a word-stem completion task for the words (e.g., tree) from the TBR and TBF items and a free recall task. Both children and adults provided more TBR than TBF items in the word stem completion and the free recall task, although adults showed a larger difference between TBR and TBF items, indicating greater directed forgetting ability with age.

In contrast to list method, item method directed forgetting effects such as Lehman et al.’s (1997) are commonly thought to occur at the encoding stage of memory (Hasher & Zacks, 1994, in Wilson & Kipp, 1998). More specifically, it is hypothesized that participants selectively rehearse the TBR items substantially more than the TBF items (Sheard & MacLeod, 2005). Participants may begin rehearsing an item, but immediately stop further processing when they receive the forget cue, whereas the presentation of a remember cue leads them to make further efforts to memorize an item (Anderson, 2005). In line with the age increases in directed forgetting tasks using an item method, children’s rehearsal ability increases between 5 and 10 years of age (e.g., Flavell, Beach, & Chinsky, 1966). In addition, children’s ability to selectively pay attention to stimuli that are important and ignoring those that are not also increases between 2nd and 6th grade (e.g., Huang-Pollock, Carr, & Nigg, 2002), which would further enable their use of a selective rehearsal strategy on an item-method directed forgetting task.

Laboratory-based experiments on directed forgetting, like those conducted by Harnishfeger and Pope (1996) and Lehman et al. (1997), enable the manipulation of stimulus materials and control of other important factors and are therefore important for studying the cognitive processes responsible for directed forgetting. Research on directed forgetting outside of the laboratory is relatively rare, and has so far only been carried out with adult participants. As an example, Joslyn and Oakes (2005) gave journals to college students and instructed them to record memorable events from their daily routines for one week. At the end of the first week, they were told to forget the past week’s events and to focus instead on the next week’s events. At the end of the second, week participants were asked to recall both events from the to-be-forgotten week and to-be-remembered week. Results showed a significant difference in recall with TBR information recalled at a higher rate than TBF items. The findings of this study provide support for the hypothesis that people can intentionally forget personally experienced events. However, the events were not standardized across participants, leading to potential problems. In addition, it seems that most participants recorded short and simple events, like witnessing a crow chasing a squirrel and exchanging funny animal stories with his/her friends (p. 579). In the present study, we wanted to test whether it would be possible to get a directed forgetting effect when telling children of different ages to forget a complex real-life event immediately after it happened, using the same event for all children. The current study also examined directed forgetting in a traditional word-list paradigm modeled after Harnishfeger and Pope’s (1996) work to see if directed forgetting effects are different depending on whether a child is instructed to forget an experience versus a list of words.

Method

Participants

A total of 15 1st graders (M age in months = 83.20; SD = 7.17), 9 3rd graders (M age in months = 107.30; SD = 11.30), and 9 5th graders (M age in months = 127.50; SD = 7.50) participated in this study. Participants were recruited by sending invitation letters home with 1st, 3rd, and 5th grade students from two elementary schools in a rural Midwestern region. The sample was ethnically diverse (70.60 percent Caucasian, 20.60 percent African-American, and 5.90 percent Hispanic) and included equal numbers of boys and girls.

Design

Each participant was engaged in two science activities, namely, making a lemon battery and building an electromagnet. Both the order in which the two activities were administered and which of the two activities was followed by the forget instruction were counterbalanced, producing four experimental conditions. Within each age group, participants were randomly assigned to one of these conditions with the constraint of approximately equal distribution of children across conditions. Following a two-week delay, all participants were questioned about both activities.

Materials and Procedure

Activities (Session 1). Before commencing the science activities, the experimenter verbally assessed each participants’ knowledge of batteries and electricity and provided corrective feedback if necessary. Construction of the lemon battery required a lemon, a penny, a galvanized nail, a knife, a voltmeter, and some wet wipes. First, the experimenter and the participant together labeled each of the items used. Next, the researcher asked the participant to remove a sticker from the lemon, and then the participant used a wet wipe to clean the lemon. The experimenter then touched the positive and negative ends of a voltmeter to the outside of the lemon to show the child that no electricity was flowing at this point. Next, the experimenter took a knife to cut slits into the lemon. He asked the child to assist by putting a penny into one slit and the galvanized nail into another slit. The voltmeter was then clamped onto both of these battery posts, and the experimenter drew the participant’s attention to its display that indicated the lemon produced some electricity.

Building the electromagnet involved a 6-volt battery, a wire approximately two feet in length with pre-stripped ends, a nail, and three paper clips. The activity followed a similar script to that described for the lemon battery. After the joint labeling of items, the researcher first moved the unattached nail over the paper clips (allowing the child to do so as well) to demonstrate the absence of magnetic attraction. He then asked the child to wipe the wire and nail clean. Next, the experimenter wrapped the insulated 18-gauge wire around the nail several times before attaching the stripped wire ends to each battery post. After the researcher connected the two wire ends to the battery posts, the electricity flowing over the nail magnetized it. To demonstrate this phenomenon, the experimenter moved the nail over the paper clips a second time, and the child watched the nail attracting the paper clips. Finally, the child was allowed to move the nail over the paper clips and feel the attraction for him/herself.

Memory Interviews (Session 2). The second session occurred approximately two weeks later and began with the experimenter interviewing each participant about both science activities. The experimenter explained to participants that although they were instructed to remember one activity and forget the other, they would now be interviewed about both activities in the order in which the activities were completed. A standardized set of questions was used for each of the two activities, beginning with very general open-ended questions (e.g., “Please tell me everything that you can remember about making the lemon battery.”), moving to cued (e.g. “What did we use to make a lemon battery?”), and finally very specific questions (e.g., “How many times did we wash the lemon?”).

Word List Directed Forgetting (Session 2). Using the procedure outlined in Harnishfeger and Pope (1996), we created two sets of twenty simple, unrelated words each (e.g., dog, theater, glass). The first ten words of the first set were the last ten words of the second set, and vice versa. Participants were instructed to listen and remember as the experimenter read some words to them. After only ten words were read the experimenter gave a surprise forget cue, instructing the participants that, “The words you have heard so far have been just practice. Please forget these words and remember this next set of words.” After reading the remaining ten words to the participant, the participant was asked to count backwards from thirty as a distracter task. After counting backwards, the participants were asked to recall as many words as they could from both the “practice” and the “real” list.

Results

Real-Life Events

We first examined directed forgetting and age differences in directed forgetting for total event recall, which was calculated as the number of items a participant recalled combined across open-ended, cued, and specific recall. A mixed ANOVA with event recall (TBR and TBF) as a within-subjects factor and grade (1, 3, and 5) as a between-subjects factor was run. A significant main effect for grade was found F(2, 30) = 5.07, p = .01, η2 = .25 (see Figure 1). A Scheffe post hoc test was conducted and revealed significant differences between 1st and 5th grade (MD = 2.98, SE = 1.04, p = .03) but not between 3rd and 5th grade (MD = .56, SE = 1.16, p = .89) or 1st and 3rd grade (MD = 2.43, SE = 1.04, p = .08). The ANOVA revealed no significant effect for the event F(1, 30) = .75, p = .39, η2 = .02 nor a significant interaction between grade and event F(2, 30) = .48, p = .63, η2 = .03. These findings suggest that memory for a real-life event improves with age, especially between 1st and 5th grade. These results also show there was no directed forgetting regardless of age.

Figure 1
Total Recall of To-be-Forgotten (TBF) and To-be-Remembered (TBR) Event by Grade

Open-ended recall was deemed to be the most sensitive measure of memory because it does not provide participants with memory cues. A mixed model ANOVA with event (TBR and TBF) as a within-subjects factor and grade (1, 3, and 5) as a between-subjects factor was conducted to examine age differences in open-ended recall of real-life events. A significant effect for grade was found F(2,30) = 3.86, p = .03, η2 = .21 (see Figure 2). A Scheffe post hoc test found that 1st grade open-ended recall differed significantly from that of 5th graders (MD = 2.61, SE = 1.01, p = .05), but 1st grade did not differ significantly from 3rd grade (MD = 1.94, SE = 1.01, p = .17), and 3rd grade did not differ from 5th grade (MD = .67, SE = 1.13, p = .84), showing that overall memory performance increased with age. Similar to the total recall results, the ANOVA revealed no significant main effects for event F(1,30) = .01, p = .91, η2 = .00, nor an interaction between event and grade F(2,30) = .93, p = .41, η2 = .06. A summary of all means, standard deviations may be seen in Table 1. These results imply that although no open-ended directed forgetting differences occur with grade, the open-ended recall improves with age regardless of TBR and TBF cues.

Figure 2
Open-Ended Recall of To-be-Forgotten (TBF) and To-be-Remembered (TBR) Event by Grade

Table 1
Average Levels of To-be-Forgotten (TBF) and To-be-Remembered Information by Grade (Standard Deviations in Parentheses)

Word Lists

Word list directed forgetting was assessed in a recall test during session 2 in which participants were instructed to recall as many words as possible. TBR items were words recalled from the remember-cued list and TBF items were words recalled from the forget-cued list. The forget- and remember-cues (word lists) served as the independent variables, and item recall was the dependent variable. To examine the effect of age and forget cue on word recall, a mixed model ANOVA was run with word list (TBR and TBF) as a within-subjects factor and grade (1, 3, and 5) as a between-subjects factor. A significant main effect for word list was found F(1, 30) = 4.78, p = .04, η2 = .14, showing that overall more TBR words were remembered than TBF words. A Scheffe post hoc test revealed no significant differences between grades, however, the difference between 1st and 5th grade was closest to significance (MD = .89, SE = .47, p = .18) suggesting that directed forgetting for word lists does increase with age. No significant main effect was found for grade F(2, 30) = 1.79, p = .18, η2 = .11, nor was a significant interaction between forget cue was revealed F(2, 30) = 1.01, p = .38, η2 = .06 (see Figure 3). These findings suggest that word list directed forgetting is occurring and it does vary significantly between grades.

Figure 3
Recall of To-be-forgotten (TBF) and To-be-remembered (TBR) Words by Grade

Discussion

The main finding of this study was the absence of directed forgetting of real-life events at any age or recall level. In contrast, children did show the age-related trend for increasing directed forgetting for word lists previously reported in the literature (e.g., Harnishfeger & Pope, 1996). One reason that we did not find directed forgetting for real-life events might be that complex personal experiences are difficult to forget after only a short period of time, even when someone tells you to forget them. Supporting this interpretation, Murachver, Pipe, Gordon, Owens, and Fivush (1996) compared children’s memory for a “visit to the pirate” event depending on whether they had experienced it for themselves, observed someone else experience it, or only heard a story about it. Children with direct experience recalled more information than those in the other two conditions, and produced significantly fewer memory errors, which implies that memory for personal experiences may be well remembered.

It is also possible that the current study suffered from methodological shortcomings. Perhaps the children represented what was intended to be two distinct events (lemon battery and electromagnet) as one single encompassing “science event.” The real-life events may be an example of how one’s perception of an experience affects how it is represented in memory. For example, the experimenter thought of the events as two different experiences, whereas the children may have perceived them as only one large event – and one that stuck out from their normal daily routine at that. Another potential concern was that even if children did treat the two events as separate entities, they may have failed to remember which of the two was to be remembered and which was to be forgotten over the delay interval. To address this possibility, each participant was asked at the beginning of the second session which event was TBF and which was TBR, and every child without exception correctly remembered this information. Children may in fact even have used the forget cue not as an instruction to forget, but as an instruction of what not to remember, as suggested by Golding and Keenan (1985). Thus, similar to thought suppression experiments (e.g., Whetstone & Cross, 1998), participants may have used the forget cue as an instruction to, in effect, keep the TBF item in their minds because it told them what not to remember. In such an instance, instead of leading children to show directed forgetting, the forget cue may actually lead them to keep the information that is targeted by the forget cue in mind.

There are also, however, plausible conceptual as opposed to methodological explanations for the lack of directed forgetting of real-life events. For instance, the pattern of findings might reflect the context specificity of memory. Whereas the real-life event may create multiple and strong memory traces and cues that trigger later recall, word lists are made up of random unrelated words that may not create strong traces or cues and are so more easily forgotten. Consistent with this idea, Gobbo, Mega, and Pipe (2002) found that children had better recall for events that they participated in as opposed to recall for events that they only watched or listened to. For the children in the present experiment, even the TBF event provided them with input from many various “channels,” such as tactile, olfactory, visual, and auditory stimuli – all of which may have led to the establishment of strong memory representations and provide effective recall cues.

Participants may have also lacked the motivation to intentionally forget the TBF event. For example, in real-world scenarios in which intentional forgetting takes place, such as child abuse, the abused children may have a very strong desire to forget certain experiences (e.g., Conway, 1995; Freyd, 1996). Both of the events in this study were presumably equal with regards to stimulating the children’s interest and their emotional impact. More importantly, the participants had no real reason to forget one event over another, other than the experimenter’s request. The children most likely perceived the entire experiment as a fun learning experience that they might even want to remember.

Nevertheless, directed forgetting for real-life events has been established (e.g., Joslyn & Oakes, 2005). The directed forgetting found by these researchers may be attributed to the fact that they worked with adults. Perhaps adults have better developed the necessary mechanisms required for real-life directed forgetting. It has, after all, been shown that word list directed forgetting continues to improve into adulthood (e.g., Harnishfeger & Pope, 1996). Also, Joslyn and Oakes may have found directed forgetting because their experimental design allowed for a strong segregation of TBF and TBR events; the events took place one week apart, and thus aided the participants in determining which events to forget and remember.

The finding that directed forgetting of word lists increases with age, however, suggests that people are capable of forgetting certain memories once a certain level of cognitive maturity has been achieved. Children do develop some sort of mechanisms to create directed forgetting. Although, no significant directed forgetting was found within each individual grade, a strong overall trend was found similar to that of Harnishfeger and Pope (1996).

Future research in the area of directed forgetting should continue to explore the link between word list directed forgetting and real-life directed forgetting. Future directions for research in this area should also seek to resolve the issue of real-life events deviating too far from a child’s daily routine. A more regular activity should be adopted, rather than activities that children have never been exposed to. Another interesting facet that should be examined is the idea of unique experiences versus repeated experiences. A repeated exposure experiment with real-life directed forgetting would give the study even more external validity. A repeated exposure study contains the possibility of better understanding an abused child’s memory for repeated events as opposed to a one-time occurrence. Motivation and emotional connection should also be explored. It may be important to measure how much a child’s motivation to forget or remember as well as how their emotional connection and direction affect directed forgetting performance.

References

Anderson, M. C. (2005). The role of inhibitory control in forgetting unwanted memories: A consideration of three methods. In N. Ohta, C. M. MacLeod, & B. Uttl (Eds.), Dynamic cognitive processes (pp. 219-248). Tokyo: Springer-Verlag.

Bjork, R. A. (1972). Theoretical implications of directed forgetting. In A.W. Melton & E. Martin (Eds.), Coding processes in human memory (pp. 217-235). Washington, DC: Winston.

Bjorklund, D. F., & Harnishfeger, K. K. (1990). The resources construct in cognitive development: Diverse sources of evidence and a theory of inefficient inhibition. Developmental Review, 10, 48-71.

Conway, M. A. (1995). Flashbulb memories. East Sussex, UK: Lawrence Erlbaum Associates.

Dempster, F. N. (1993). Resistance to interference: Developmental changes in basic processing mechanisms. In M.L. Howe & R. Pasnak (Eds.), Emerging themes in cognitive development: Vol. 1: Foundations (pp. 3-27). New York: Springer-Verlag.

Flavell, J. H., Beach, D. R., & Chinsky, J. M. (1966). Spontaneous verbal rehearsal in a memory task as a function of age. Child Development, 37, 283-299.

Freyd, J. J. (1996). Betrayal trauma: The logic of forgetting childhood abuse. Cambridge, MA: Harvard University Press.

Gobbo, C., Mega, C., & Pipe, M. (2002). Does the nature of the experience influence suggestibility? A study of children’s event memory. Journal of Experimental Child Psychology, 81, 502-530.

Golding, J. M., & Keenan, J. M. (1985). Directed forgetting and memory for directions to a destination. The American Journal of Psychology, 98, 579-590.

Harnishfeger, K. K., & Pope, R. S. (1996). Intending to forget: The development of cognitive inhibition in directed forgetting. Journal of Experimental Psychology, 62, 292-315.

Huang-Pollock, C. L., Carr, T. H., & Nigg, J. T. (2002). Development of selective attention: Perceptual load influences early versus late attentional selection in children and adults. Developmental Psychology, 38, 363-375.

Joslyn, S. L., & Oakes, M. A. (2005). Directed forgetting of autobiographical events. Memory & Cognition, 33, 577-587.

Lehman, E. B., McKinley-Page, M., Wilson, J. A., Slavsky, M. D., & Woodson, M. E. (1997). Direct and indirect measures of intentional forgetting in children and adults: Evidence for retrieval inhibition and reinstatement. Journal of Experimental Child Psychology, 64, 295-316.

Murachver, T., Pipe, M. E., Gordon, R., Owens, J. L., & Fivush, R. (1996). Do, show, and tell: Children’s event memories acquired through direct experience, observation, and stories. Child Development, 67, 3029-3044.

Sahakyan, L., & Kelley, C. M. (2002). A contextual change account of the directed forgetting effect. Journal of Experimental Psychology: Learning, Memory, & Cognition, 28, 1064-1072.

Sahakyan, L., & Goodmon, L. B. (2007). The influence of direction al associations on directed forgetting and interference. Journal of Experimental Psychology: Learning, Memory, & Cognition, 33, 1035-1049.

Sheard, E. D., & MacLeod, C. M. (2005). List method directed forgetting: Return of the selective rehearsal account. In N. Ohta, C. M. MacLeod, & B. Uttl (Eds.), Dynamic cognitive processes (pp. 219-248). Tokyo: Springer-Verlag.

Whetstone, T. & Cross, M. D. (1998, November). Control of conscious contents in directed forgetting and thought suppression. Psyche, 4. Retrieved June 5, 2007 from http://psyche.cs.monash.edu.au/vy/psyche-4-16-whetstone.html.

Wilson, S. P., & Kipp, K. (1998). The development of efficient inhibition: Evidence from directed-forgetting tasks. Developmental Review, 18, 86-123.

Directed Forgetting of Real-Life Events in School-Age Children

Michael Anthony Cole Jr.
Holger B. Elischberger*
Albion College

Abstract

Introduction

Method

Participants

Design

Materials and Procedure

Results

Real-Life Events

Word Lists

Discussion

References

Directed Forgetting of Real-Life Events in School-Age Children Michael Anthony Cole Jr. Holger B. Elischberger* Albion College

Abstract

Introduction

Method

Participants

Design

Materials and Procedure

Results

Real-Life Events

Word Lists

Discussion

References

Directed Forgetting of Real-Life Events in School-Age Children

Michael Anthony Cole Jr.
Holger B. Elischberger*
Albion College