Recalling yesterday and predicting tomorrow

Abstract

Three-, 4- and 5-year-old children were asked to report something that they did do yesterday and something that they were going to do tomorrow. They were also asked to recall events that had not occurred yesterday, and predict events that would not occur tomorrow. In two studies these simple questions revealed striking age differences in the ability to report personal events from the past and the future. Only a minority of 3-year-olds but a majority of the older children were able to appropriately answer these questions. These findings substantiate the proposal that the ability to recall past events and the ability to predict future events (i.e., mental time travel), emerge in tandem between the ages of 3 and 5 years.

Full text

Cognitive Development 20 (2005) 362–372
Recalling yesterday and predicting tomorrow
Janie Busby∗, Thomas Suddendorf
School of Psychology, The University of Queensland, St. Lucia, Qld 4072, Australia
Abstract
Three-, 4- and 5-year-old children were asked to report something that they did do yesterday and
something that they were going to do tomorrow. They were also asked to recall events that had not
occurred yesterday, and predict events that would not occur tomorrow. In two studies these simple
questions revealed striking age differences in the ability to report personal events from the past and the
future. Only a minority of 3-year-olds but a majority of the older children were able to appropriately
answer these questions. These findings substantiate the proposal that the ability to recall past events
and the ability to predict future events (i.e., mental time travel), emerge in tandem between the ages
of 3 and 5 years.
© 2005 Elsevier Inc. All rights reserved.
Keywords: Episodic memory; Anticipation; Amnesia; Mental time travel
Much of adult behaviour is dictated not only by current context, but also by recollections
of past events and anticipation of future scenarios (Atance & O’Neill, 2001;Suddendorf
& Corballis, 1997;Tulving, 2002;Wheeler, Stuss, & Tulving, 1997). Debate about mental
timetravel(MTT)intothepastandfuture,whilelargelyfocusedonwhethernon-humanani-
mals have this capacity (Clayton, Bussey, & Dickinson, 2003;Hampton & Schwartz, 2004;
Suddendorf & Busby, 2003;Suddendorf & Corballis, 1997), has also surged in the devel-
opmental arena, with researchers asking when children become capable of MTT (Atance
& O’Neill, 2001;Moore & Lemmon, 2001;Suddendorf & Corballis, 1997;Wheeler et al.,
1997).
MTT into the past is based on episodic memory, a subtype of the declarative (or explicit)
memory system (e.g., Squire, 1992;Squire, Knowlton, & Musen, 1993), and is defined
∗Corresponding author. Tel.: +61 7 3365 6774; fax: +61 7 3365 4466.
E-mail address: janie@psy.uq.edu.au (J. Busby).
0885-2014/$ – see front matter © 2005 Elsevier Inc. All rights reserved.
doi:10.1016/j.cogdev.2005.05.002

J. Busby, T. Suddendorf / Cognitive Development 20 (2005) 362–372 363
as the recall of previously experienced events, accompanied by a sense of reliving that
particular event “as happening to me”. Episodic memory can be dissociated from the other
component of declarative memory, semantic memory (general knowledge or facts about the
world), both through impairment and task manipulations (Klein, Loftus, & Kihlstrom, 2002;
Tulving, 1985; see review by Gardiner, 2002; and meta-analysis by Gardiner, Ramponi,
& Richardson-Klavehn, 2002). Recent literature proposes that episodic memory may not
emerge until 3 to 5 years of age (e.g., Perner & Ruffman, 1995;Pillemer & White, 1989;
Suddendorf & Corballis, 1997;Wheeler et al., 1997).
Evidencein support ofthis claim includesthe phenomenon ofinfantile amnesia (Dudycha
& Dudycha, 1933;Kihlstrom & Harackiewicz, 1982;Sheingold & Tenney, 1982). One
possible explanation for infantile amnesia is that only by 3 to 4 years of age does episodic
memory mature, allowing events experienced after this time to be episodically encoded and
thus reconstructed at a later date (Pillemer & White, 1989;Suddendorf & Corballis, 1997).
Further, young children’s own reports of past events seem to be qualitatively different from
those of older children and adults (Fivush, Gray, & Fromhoff, 1987;Fivush & Hamond,
1990;Todd & Perlmutter, 1980), lacking temporal and causal structure (Fivush, Haden,
& Adam, 1995;Pillemer, Picariello, & Pruett, 1994), and being heavily reliant on cues
from the interviewer (see reviews by Howe & Courage, 1997;Pillemer & White, 1989).
Evidence from assessments of free recall, source memory (how you know what you know)
and reality monitoring by preschool children also suggest that the ability to recall past events
is undergoing significant changes during this period (Ceci & Howe, 1978;Ceci, Ross, &
Toglia, 1987;Gopnik & Graf, 1988;Ornstein, Gordon, & Larus, 1992;Perner & Ruffman,
1995;Sodian & Wimmer, 1987;Wimmer, Hogrefe, & Perner, 1988; see review by Ceci &
Bruck, 1993).
The pre-experiencing of possible future events, episodic future thinking, can be distin-
guished from script-like (semantic) knowledge about the future in much the same way as
episodic and semantic memory can be distinguished (Atance & O’Neill, 2001; Suddendorf
& Busby, 2003;Suddendorf & Corballis, 1997). Hudson, Shapiro, and Sosa (1995), for
example, found that children’s ability to plan for a specific future event improved between
3 and 5 years of age, but their ability to report a script (“what usually happens”) for that
event did not change. Atance and O’Neill (2001) found significant gains during the fourth
year of life in verbal referencing of the future when constructing plans. There is also evi-
dence that during the preschool years children become better at selecting delayed future
rewards, perhaps based on their ability to conceptualise that future event (Moore, Barresi, &
Thompson, 1998;Thompson, Barresi, & Moore, 1997). These findings support a devel-
opmental differentiation between episodic and semantic constructions in the future that
parallels that reported above for the past.
In line with this parallel, Suddendorf and Corballis (1997) proposed that both mental
time travel into the past and into the future (i.e., episodic memory and episodic future think-
ing) draw on the same mechanisms and depend on the development of the same set of basic
capacities including recursion, self-awareness, metarepresentation, and the ability to disso-
ciate current from imagined states (see also Suddendorf & Busby, 2003). Some empirical
support for a link between MTT into the past and future comes from neuropsychology.
Tulving (1985; Tulving, Hayman, & Macdonald, 1991) and Klein et al. (2002) presented a
series of recall questions to their patients K.C. and D.B. These patients suffer from severe

364 J. Busby, T. Suddendorf / Cognitive Development 20 (2005) 362–372
episodic memory impairment, while displaying relatively spared semantic memory. They
were unable to answer simple questions about their own past experiences (e.g., “what did
you do yesterday?”), although these same patients could answer general knowledge ques-
tions about the past. Similarly, they were unable to report events that might occur to them in
the future, although again these patients had general knowledge about the future (Klein et
al., 2002; Tulving, 1985; Tulving et al., 1991). This simple questioning thus revealed par-
allel impairments in MTT into the future and MTT into the past, suggesting a link between
the two.
When can children report events from the past and predict future events in such basic
interviews and do these abilities emerge in tandem? To our knowledge only one study
has directly asked young children similar questions, although only about the past. Friedman
foundthat children aged 4 years and over couldcorrectly report a specific event thatoccurred
to them “yesterday” (amongst questions about other time spans, Friedman, 1992). Thus, it
remains unknown whether younger children can respond appropriately to such questions.
We are not aware of any study asking such questions about the future, let alone asking the
same children parallel questions about past and future. So we set out to do so.
We asked children aged 3 to 5 years to report events from their past (yesterday) and
to predict future events (tomorrow). Questions like “what did you do yesterday?” replicate
everyday conversational patterns between parents and children and may lead to the expecta-
tion that even very young children can reply appropriately. On the other hand, the evidence
reviewedabovesuggeststhat MTT emergesrelativelylate in developmentandhence predicts
that only older children (of about 4 to 5 years of age) would be able to answer appropriately.
If MTT into the past and MTT into the future draw on the same mechanisms one would
expect both types of questions to be equally difficult and performance to be associated.
We also asked children negation questions about the past and the future. We reasoned that
when children become capable of projecting themselves mentally into the past and future,
they should be able not only to report on what happened (or will happen), but also on what
did not happen (or will not happen). We might hence expect to find capacities similar to
those on the positive questions. Thus, we decided to ask them to name events they had not
experienced yesterday, and would not experience tomorrow. Although by 3 and 4 years of
age children spontaneously discuss non-events (Todd & Perlmutter, 1980), little is known
about the development of children’s ability to report events that did not or will not occur.
Therefore, the current studies simply asked young children to report events that did or did
not occur yesterday and events that they did or did not anticipate to occur tomorrow.
1. Experiment 1
1.1. Method
1.1.1. Participants
Forty children aged 3 years old (36–47 months) and 4 years old (48–59) (n=20 per age
group) were recruited from the Early Cognitive Development Unit database in Brisbane,
Australia. Three-year-olds were on average 40.3 months of age (S.D. =3.8 months; 10 boys,
10 girls) and 4-year-olds 52.8 months (S.D.= 3.9 months; 8 boys, 12 girls).

J. Busby, T. Suddendorf / Cognitive Development 20 (2005) 362–372 365
1.1.2. Procedure
Children were interviewed in a testing room at the University of Queensland with the
child’s parent/s present. Children were asked the following four recall questions, “can you
tell me something that you did yesterday?” (yesterday positive question) “can you tell
me something that you didn’t do yesterday?” (yesterday negative question), “can you tell
me something you are going to do tomorrow?” (tomorrow positive question) and “can
you tell me something you are not going to do tomorrow?” (tomorrow negative question).
The order of presentation of past and future questions was counterbalanced across children.
Within each tense type the positive question was always asked first, followed by the negative
question (pilot tests revealed children tended to list events which did occur before discussing
events which did not). If the child responded with “I don’t know” or a similar statement,
they were prompted with the question again. If the child produced a general response
(e.g., “I played”) they were prompted for a more specific answer (e.g., “what did you play
yesterday?”).
1.1.3. Scoring
Children’s responses were coded in two different ways. Firstly the child was scored as
to whether they could generate a specific event in answer to each question, regardless of
whether this event did or would actually occur. The child did not need to produce an entire
sentence, rather just a term that was interpretable as an activity (e.g., “painted”). Scoring
did not depend on whether the event occurred regularly or rarely. The child’s response to
each question was also evaluated as either correct or incorrect by the parent. The parent
indicatedto the researcherthat the child’sanswerwas likelycorrect or incorrect (i.e.,whether
it occurred or did not occur on that specific day) using non-verbal signals (the parent sat
behind the child, and therefore their responses were only visible to the researcher).
1.2. Results and discussion
Preliminary analyses revealed no gender differences on any of the questions, thus the
data were collapsed across gender.
Forty-five percent of 3-year-olds and 65% of 4-year-olds produced an answer to the
yesterday question. Similarly, 60% of 3-year-olds and 80% of 4-year-olds could do so
on the tomorrow question. These age differences were not significant (yesterday χ2(1,
N=40)=1.616, p=.204; tomorrow χ2(1, N=40) =1.905, p= .168).
Producing an answer does, of course, not mean that the child did in fact recall or pre-
dict an event that did or would actually occur. Fig. 1 displays the percentage of 3- and
4-year-old children reporting events from yesterday and tomorrow that parents judged to
be correct. More than half of 4-year-olds (55% and 65% on past and future questions,
respectively) generated answers parents judged as correct, compared with a minority of
3-year-olds (30% on each question). This age difference was significant for the future
question (χ2(1, N=40)=6.465, p=.011) but failed to reach significance for the past ques-
tion (χ2(1, N=40)=2.558, p=.11). Examples of children’s responses are provided in
Table 1.
As predicted, there was a significant positive correlation between performances on the
yesterday and tomorrow questions (ϕ(40) = .341, p= .031). Overall, there was no suggestion

366 J. Busby, T. Suddendorf / Cognitive Development 20 (2005) 362–372
Fig. 1. Percentage of 3- and 4-year-olds producing a correct answer in response to the yesterday and tomorrow
event questions in Experiment 1.
in the data that questions about the past were easier than questions about the future, or vice
versa (Sign test p=1,N= 40). These findings thus support the hypothesis that the ability
to report events in the past and the future develop in parallel. In sum, the results suggest
that although 3-year-olds can produce answers to questions about events displaced in time
much like 4-year-olds, their responses do not appear to reflect actual recall or prediction, at
least as judged by parents.
In contrast to the positive questions, 3-year-olds in this study had some problems gen-
erating answers to negative questions (examples are shown in Table 1). Significantly more
4-year-olds than 3-year-olds could produce events that did not or will not occur, with 22%
of 3-year-olds and 70% of 4-year-olds responding to the yesterday non-event question and
25% and 80% responding to the tomorrow non-event question (yesterday negative χ2(1,
N=40)=12.130, p<.001; tomorrow negative χ2(1, N=38) = 8.674, p= .003). A similar
pattern of results emerged when parents judged the events as correct or incorrect. Only 20%
(past) and 11% (future) of 3-year-olds produced answers to the non-event questions that
parents judged to be correct. By contrast, 60% of 4-year-olds did so on both questions. This
age difference is significant (see Fig. 2; yesterday negative question χ2(1, N=40) = 6.667,
p= .01; tomorrow negative question χ2(1, N=38) =9.731, p= .002). There were no signifi-
cant differences between scores on positive and negative questions. These findings suggest
that it is not until 4 years of age that a majority of children can generate a response (whether
Table 1
Examples of children’s correct and incorrect responses to each question type in Experiment 1, including child’s
age and gender
Question type Child’s age Gender Response Correct/incorrect
Yesterday +ve 3;0 Male “Went on a swing” Correct
Yesterday +ve 3;0 Male “The beach” Incorrect
Yesterday −ve 4;0 Female “Didn’t go shopping” Correct
Yesterday −ve 4;2 Female “Didn’t do drawing” Incorrect
Tomorrow +ve 4;0 Female “Play Uno with mummy” Correct
Tomorrow +ve 4;0 Male “Go swimming” Incorrect
Tomorrow −ve 4;0 Male “Not going to the big slippery slide” Correct
Tomorrow −ve 4;5 Male (Won’t) “play in the toy room” Incorrect

J. Busby, T. Suddendorf / Cognitive Development 20 (2005) 362–372 367
Fig. 2. Percentage of 3- and 4-year-olds producing a correct answer in response to the yesterday and tomorrow
non-event questions in Experiment 1.
correct or incorrect) to a non-event question, a pattern that suggests that the negative request
itself may be difficult for younger children to understand. By age 4, however, the results
suggest that children can report appropriate past and future events as well as name events
that did not happen yesterday and are not likely to occur tomorrow.
2. Experiment 2
In Experiment 2 we attempted to replicate the findings of Experiment 1, and introduced
three minor amendments. In Experiment 1 children’s responses were scored by parents as
correct or incorrect using non-verbal signals to the researcher. To minimise the possibility of
children noting that signal a less intrusive scoring method was implemented in Experiment
2. Another issue in the first study was the prompting schedule used with the children, which
was open to variation by children’s unexpected responses. In Experiment 2 this prompting
schedule was standardised to allow a maximum of two repetitions of the question. Finally,
given that the oldest age group in Experiment 1, 4-year-olds, were not performing at ceiling,
a 5-year-old age group was also included in Experiment 2.
2.1. Method
2.1.1. Participants
Forty-eight children aged 3 years old (39–45 months), 4 years old (51–57) and 5 years
old (63–69) (n=16 per age group) were recruited from the Early Cognitive Development
Unit database. Three-year-olds were on average 41.4 months of age (S.D.= 1.7 months; 6
boys, 10 girls), 4-year-olds 53.6 months (S.D. =2.3 months; 7 boys, 9 girls) and 5-year-olds
64.9 months (S.D.=1.5 months; 7 boys, 9 girls).
2.1.2. Procedure
The procedure was implemented as described in Experiment 1, excepting the following
changes. Before the experiment began parents were given a response sheet and appropriate
instructions. Parents recorded on the response sheet their child’s answer to each question in
note form, and whether they believed it was a correct or incorrect answer. The researcher’s

368 J. Busby, T. Suddendorf / Cognitive Development 20 (2005) 362–372
Fig. 3. Percentage of 3-, 4- and 5-year-olds producing a correct answer in response to the yesterday and tomorrow
event questions in Experiment 2.
script was also standardised so that two prompts were given if the child did not respond to
the initial question. Children’s answers were coded as in Experiment 1.
2.2. Results and discussion
Preliminary analyses revealed no gender differences on any of the questions, thus the
data were collapsed across gender.
All three age groups performed close to ceiling on the yesterday event question when
parentaljudgements of event accuracywas ignored, with 94% of 3-year-olds,80% of 4-year-
olds and 100% of 5-year-olds reporting an event. In response to the tomorrow question, 69%
of 3-year-olds, 88% of 4-year-olds and 100% of 5-year-olds produced a specific event. This
was a significant improvement in performance from 3- to 5-year-olds on the tomorrow ques-
tion (χ2(1, N= 32)= 5.926, p=.015), but not the yesterday question (χ2(2, N= 47) = 4.136,
p=.126).
Fig. 3 displays the percentage of children reporting events judged as likely by parents.
The results closely replicated Experiment 1, with 25% and 31% of 3-year-olds and 56% and
69% of 4-year-olds correctly reporting events from yesterday and tomorrow. Seventy-five
percent and 63% of 5-year-olds correctly produced answers to the yesterday and tomor-
row questions. Four-year-olds significantly outperformed 3-year-olds on both the yesterday
question (χ2(1, N=31)=3.895, p=.048) and the tomorrow question (χ2(1, N=32) = 4.50,
p=.034),butthere were no significant differences between the 4- and 5-year-oldage groups.
Unlike the first experiment, responses to the past and future questions were not sig-
nificantly related (ϕ(47)=.145, p=.319, this was also non-significant when only 3- and
4-year-olds were included in the analysis). However, as in Experiment 1, participants did
not perform better on past than future questions, or vice versa (Sign test p=1,N= 47). Thus,
although a significant correlation between the two questions was not found in this second
experiment, there is again support for the hypothesis that the ability to report events of the
past and of the future emerge in parallel.
In response to the negative questions, 75%, 63% and 87% of 3-, 4- and 5-year-olds,
respectively, produced a non-event in the past, compared with 53%, 67% and 93% in the
future.This differenceacross age groupswas only significanton the future question,between

J. Busby, T. Suddendorf / Cognitive Development 20 (2005) 362–372 369
Fig. 4. Percentage of 3-, 4- and 5-year-olds producing a correct answer in response to the yesterday and tomorrow
non-event questions in Experiment 2.
3- and 5-year-olds (future χ2(1, N=30) = 6.136, p= .013; past χ2(2, N= 47) = 2.382,
p=.304). The high percentage of 3-year-olds producing non-events for the past in this
second study is responsible for the different pattern of performance across the age groups,
and could be attributed to the more numerous prompts given by the interviewer in this
study compared with the first. When parental judgements of likelihood were taken into
account, 56% and 27% of 3-year-olds responded with correct answers to the past and
future questions, respectively, compared with 44% and 60% of 4-year-olds and 66% and
87% of 5-year-olds (see Fig. 4). On the tomorrow non-event question, there was a sig-
nificant difference between 3- and 5-year-olds (χ2(1, N=30) = 10.995, p= .001), with the
improvement between 3- and 4-year-olds approaching significance (χ2(1, N=30) = 3.394,
p= .065). However, there was no difference in performance between any of the age groups
on the yesterday non-event question (χ2(2, N=47) = 1.653, p= .437). The negative ques-
tions did not reveal a significant difference in performance between 4- and 5-year-old
children.There were nosignificant differencesin performance betweenpositiveand negative
questions.
3. General discussion
This study explored how preschool children answer simple questions about what hap-
pened yesterday or what might happen tomorrow. Consistent with predictions, a majority
of 4-year-olds, but only a minority of 3-year-olds, were able to correctly report events they
had experienced yesterday and would experience tomorrow. Three-year-olds were able to
report events in response to the questions, but the events they reported were often incorrect.
There was no evidence for an improvement in reporting of events between 4 and 5 years of
age.
There are at least two apparent explanations for the findings. It may be that only 4- to
5-year-old children are able to use MTT. The 3-year-olds in this study thus were unable
to report events that did or will occur as they could not episodically recall past events and
predict future events (Suddendorf & Busby, 2003;Suddendorf & Corballis, 1997;Wheeler
et al., 1997). This is consistent with evidence of source memory and free recall deficits
during the early preschool years (Ceci & Howe, 1978;Gopnik & Graf, 1988;Perner &

370 J. Busby, T. Suddendorf / Cognitive Development 20 (2005) 362–372
Ruffman, 1995;Sodian & Wimmer, 1987;Wimmer et al., 1988). The results also suggest
that the ability to report events from the past and the future develops at the same time,
consistent with the hypothesis that MTT into the future and the past use similar cognitive
resources (Suddendorf & Corballis, 1997). According to this account, 3-year-olds’ incorrect
reports would reflect their inability to mentally travel in time. Their responses may be little
more than guesses prompted by the question, a legitimate possibility given the very low
threshold set for what qualified as reporting of an event.
An alternative account of the data, however, is that 3-year-olds have a poor understanding
of the two temporal location terms used in the study, “yesterday” and “tomorrow”. It is
well known that children’s understanding of temporal concepts is undergoing key changes
during the preschool years (see review by Friedman, 2003; also Harner, 1975, 1982), so
it could be that 3-year-olds interpret the terms “yesterday” and “tomorrow” differently,
perhaps as referring to any temporal displacement. They may thus actually recollect or
anticipate an episode, but merely fail to report events that fall into the time frame we
consider these words to refer to. This explanation thus suggests that children may travel
mentally in time before they have acquired an appropriate semantic understanding of these
temporal terms. This would mean, of course, that a methodology that is based on semantic
understandingoftemporalterms cannot unearth such early competence. Non-verbal designs
would be needed (Suddendorf & Busby, 2005). The same restrictions apply to interpreting
the poor performance of 3-year-olds on the negative questions. Again, it is not clear whether
3-year-olds perform poorly because they cannot yet travel mentally in time, or because
they could not yet understand the question appropriately. The current study can thus not
decide between the two explanations discussed for the poor performance of the youngest
children.
However, on the basis of the current study we can draw conclusions about the capacities
of 4- and 5-year-old children. We have established that by age 4 and 5 children are quite
capable of reporting events that have happened yesterday and will happen tomorrow. They
appear equally capable of mental time travel into the future and the past. Older preschool
children were equally competent at reporting events that did not occur yesterday or are
unlikely to occur tomorrow. At this age, at least, they do seem to have mental access to the
past and future.
These studies provide the first attempt to directly ask young children to travel mentally
into both the past and the future. The findings support previous research that suggests that
the preschool years see the emergence of episodic memory and episodic future thinking, and
provide some evidence that these two capacities emerge in tandem. Although the current
findings need to be integrated with other, less linguistically based measures, they represent
an important starting point in the development of the assessment of mental time travel in
children.
Acknowledgements
We would like to thank the parents and children who participated in these studies, and
two anonymous reviewers for their helpful comments.

J. Busby, T. Suddendorf / Cognitive Development 20 (2005) 362–372 371
References
Atance, C. M., & O’Neill, D. K. (2001). Episodic future thinking. Trends in Cognitive Sciences,5(12), 533–539.
Ceci, S. J., & Bruck, M. (1993). Suggestibility of the child witness: Historical review and synthesis. Psychological
Bulletin,113(3), 403–439.
Ceci, S. J., & Howe, M. L. (1978). Age-related differences in free recall as a function of retrieval flexibility.Journal
of Experimental Child Psychology,26, 432–442.
Ceci, S. J., Ross, D. F., & Toglia, M. P. (1987). Suggestibility of children’s memory: Psycholegal implications.
Journal of Experimental Psychology: General,116, 38–49.
Clayton, N. S., Bussey, T. J., & Dickinson, A. (2003). Can animals recall the past and plan for the future? Nature
Reviews Neuroscience,4, 685–691.
Dudycha, G. J., & Dudycha, M. M. (1933). Adolescents’ memories of preschool experiences. Journal of Genetic
Psychology,42, 468–480.
Fivush, R., Gray, J. T., & Fromhoff, F. A. (1987). Two-year-olds talk about the past. Cognitive Development,2(4),
393–409.
Fivush, R., Haden, C., & Adam, S. (1995). Structure and coherence of preschoolers’ personal narratives over time:
Implications for childhood amnesia. Journal of Experimental Child Psychology,60, 32–56.
Fivush, R., & Hamond, N. R. (1990). Autobiographical memory across the preschool years: Toward reconceptu-
alizing childhood amnesia. In R. Fivush & J. A. Hudson (Eds.), Knowing and remembering in young children:
Vol. 3 (pp. 223–248). New York, NY: Cambridge University Press.
Friedman,W.J.(1992). Children’stime memory: The development of a differentiated past. Cognitive Development,
7(2), 171–187.
Friedman, W. J. (2003). The development of a differentiated sense of the past and the future. Advances in Child
Development and Behavior,31, 229–269.
Gardiner, J. M. (2002). Episodic memory and autonoetic consciousness: A first-person approach. In A. Baddeley,
M. A. Conway, & J. P. Aggleton (Eds.), Episodic memory: New directions in research (pp. 11–30). London:
Oxford University Press.
Gardiner, J. M., Ramponi, C., & Richardson-Klavehn, A. (2002). Recognition of memory and decision processes:
A meta-analysis of remember, know, and guess responses. Memory,10(2), 83–98.
Gopnik, A., & Graf, P. (1988). Knowing how you know: Young children’s ability to identify and remember the
sources of their beliefs. Child Development,59, 1366–1371.
Hampton, R. R., & Schwartz, B. L. (2004). Episodic memory in nonhumans: What, and where, is when? Current
Opinion in Neurobiology,14, 192–197.
Harner, L. (1975). Yesterday and tomorrow: Development of early understanding of the terms. Developmental
Psychology,11(6), 864–865.
Harner, L. (1982). Immediacy and certainty: Factors in understanding future reference. Journal of Child Language,
9(1), 115–124.
Howe, M. L., & Courage, M. L. (1997). The emergence and early development of autobiographical memory.
Psychological Review,104(3), 499–523.
Hudson, J. A., Shapiro, L. R., & Sosa, B. B. (1995). Planning in the real world: Preschool children’s scripts and
plans for familiar events. Child Development,66(4), 984–998.
Kihlstrom, J. F., & Harackiewicz, J. M. (1982). The earliest recollection: A new survey. Journal of Personality,
50, 134–147.
Klein, S. B., Loftus, J., & Kihlstrom, J. F. (2002). Memory and temporal experience: The effects of episodic
memory loss on an amnesiac patient’s ability to remember the past and imagine the future. Social Cognition,
20, 353–379.
Moore, C., Barresi, J., & Thompson, C. (1998). The cognitive basis of future-oriented prosocial behavior. Social
Development,7(2), 198–218.
Moore, C., & Lemmon, K. (2001). The nature and utility of the temporally extended self. In C. Moore & K.
Lemmon (Eds.), The self in time: Developmental perspectives (pp. 1–13). Mahwah, NJ: Lawrence Erlbaum
Associates.
Ornstein, P. A., Gordon, B. N., & Larus, D. M. (1992). Children’s memory for a personally experienced event:
Implications for testimony. Applied Cognitive Psychology,6, 49–60.

372 J. Busby, T. Suddendorf / Cognitive Development 20 (2005) 362–372
Perner, J., & Ruffman, T. (1995). Episodic memory and autonoetic consciousness: Developmental evidence and
a theory of childhood amnesia. Journal of Experimental Child Psychology,59(3), 516–548.
Pillemer, D. B., Picariello, M. L., & Pruett, J. C. (1994). Very long-term memories of a salient preschool event.
Applied Cognitive Psychology,8(2), 95–106.
Pillemer, D. B., & White, S. H. (1989). Childhood events recalled by children and adults. Advances in Child
Development and Behavior,21, 297–340.
Sheingold, K., & Tenney, Y. J. (1982). Memory for a salient childhood event.In U. Neisser (Ed.), Memory observed
(pp. 201–212). San Francisco, CA: Freeman.
Sodian, B., & Wimmer, H. (1987). Children’s understanding of inference as a source of knowledge. Child Devel-
opment,58, 424–433.
Squire, L. R. (1992). Declarative and nondeclarative memory: Multiple brain systems supporting learning and
memory. Journal of Cognitive Neuroscience,4(3), 232–243.
Squire, L. R., Knowlton, B., & Musen, G. (1993). The structure and organization of memory. Annual Review of
Psychology,44, 453–495.
Suddendorf, T., & Busby, J. (2003). Mental time travel in animals? Trends in Cognitive Sciences,7(9), 391–396.
Suddendorf, T., & Busby, J. (2005). Making decisions with the future in mind: Developmental and comparative
identification of mental time travel. Learning and Motivation,36, 110–125.
Suddendorf, T., & Corballis, M. C. (1997). Mental time travel and the evolution of the human mind. Genetic Social
and General Psychology Monographs,123(2), 133–167.
Thompson, C., Barresi, J., & Moore, C. (1997). The development of future-oriented prudence and altruism in
preschoolers. Cognitive Development,12, 199–212.
Todd, C. M., & Perlmutter, M. (1980). Reality recalled by preschool children. In M. Perlmutter (Ed.), Children’s
memory: New directions for child development (pp. 69–85). San Francisco, CA: Jossey-Bass.
Tulving, E. (1985). Memory and consciousness. Canadian Psychology,26(1), 1–12.
Tulving, E. (2002). Episodic memory: From mind to brain. Annual Review of Psychology,53(1), 1–25.
Tulving, E., Hayman, C. A. G., & Macdonald, C. A. (1991). Long-lasting perceptual priming and semantic learning
in amnesia: A case experiment. Journal of Experimental Psychology: Learning, Memory and Cognition,17(4),
595–617.
Wheeler, M. A., Stuss, D. T., & Tulving, E. (1997). Toward a theory of episodic memory: The frontal lobes and
autonoetic consciousness. Psychological Bulletin,121(3), 331–354.
Wimmer, H., Hogrefe, J., & Perner, J. (1988). Children’s understanding of informational access as a source of
knowledge. Child Development,59, 386–396.