Planes, Trains, Automobiles—and Tea Sets: Extremely Intense Interests in
Very Young Children
Judy S. DeLoache
University of Virginia
University of Queensland
Yale University School of Medicine
Some normally developing young children show an intense, passionate interest in a particular category
of objects or activities. The present article documents the existence of extremely intense interests that
emerge very early in life and establishes some of the basic parameters of the phenomenon. Surveys and
interviews with 177 parents revealed that nearly one third of young children have extremely intense
interests. The nature of these intense interests are described, with particular focus on their emergence,
commonalities in the content of the interests, and the reactions of other people to them. One of the most
striking findings is a large gender difference: Extremely intense interests are much more common for
young boys than for girls.
Keywords: gender-stereotyped behavior, play interests, early childhood
Supplemental materials: http://dx.doi.org/10.1037/[0012-1622.214.171.1249].supp
We document here the existence of extremely intense interests
(EIIs) in infants and very young children. A substantial proportion
of normally developing young children become fascinated with
particular categories of objects or activities. They display a pas-
sionate, sometimes bordering on obsessive, attraction to items in
their interest category.
This phenomenon is quite familiar to many
parents, who are often mystified with respect to the origin, content,
and intensity of their child’s passion. A good sense of what we
mean by an EII is well conveyed in the following three summaries
of parent reports in a preliminary study. In these cases, the EII
concerned balls, brooms and brushes, and clothes and costumes.
From the time he was a few months old, this little boy would
stare intently at a globe lamp hanging above his changing table.
Gradually, his attraction generalized to balls and spherical objects
of any sort. He was constantly on the lookout for balls in the
environment; he would spot a gumball machine from far off and
would investigate any round object, no matter what size (including
tiny pieces of vermiculite in potting soil). He begged his parents to
buy him balls and ended up with a collection numbering in the
hundreds that he played with constantly.
Early in another boy’s second year, an interest emerged for
brooms and sweeping floors. It soon expanded to encompass
cleaning brushes and then generalized to all sorts of other
brushes— hairbrushes, paintbrushes, toothbrushes, and so on. His
parents indulged his passion to the extent that there were eventu-
ally toothbrushes in every room of the house so he would never
have to be without one.
Very early in her second year, this girl began insisting on
picking out her own clothes and trying to dress herself. She often
changed clothes several times a day and was at her happiest
playing dress-up. When she was around 4, the family attended a
Civil War reenactment, and the parents succumbed to her pleas to
buy her an expensive, child-sized antebellum-style ball gown. The
girl’s passion eventuated in the entire family becoming Civil War
These three examples illustrate the extraordinary intensity with
which some very young children become enamored of particular
kinds of objects or activities. Our criteria for an EII include that it
is relatively long lasting, shown in several different contexts
(home, friends’ homes, day care, etc.), directed toward multiple
objects/activities within the category of interest (real objects, rep-
licas, pictures, videos, etc.), and independently noticed by people
outside the immediate family (friends, extended family, teachers,
EIIs are distinctly different from security or transitional objects (e.g.,
Gulerce, 1991; Litt, 1986; Winnicott, 1953). In such cases, the child is
typically intensely attached to a single cherished object that provides a
feeling of security. Neither are we talking about the behaviors that are
characteristic of obsessive-compulsive disorder (e.g., Leonard, Goldberger,
Rapoport, Cheslow, & Swedo, 1990), such as repetitively checking, count-
ing, arranging toys, or performing elaborate rituals. The EIIs are in some
ways similar to the preoccupations and circumscribed interests shown by
children with autism-spectrum disorders (Baron-Cohen & Wheelwright,
1999; Lord, Rutter, & Le Couteur, 1994) but are less extreme, are often
shared with others, and tend to broaden and expand over time.
Judy S. DeLoache, Department of Psychology, University of Virginia;
Gabrielle Simcock, Early Childhood Development Unit, School of Psy-
chology, Macquarie University, Queensland, Australia; Suzanne Macari,
Yale Child Study Center, Yale University School of Medicine.
Correspondence concerning this article should be addressed to Judy S.
DeLoache, Department of Psychology, University of Virginia, P.O. Box
400400, Charlottesville, VA 22904-4400. E-mail: email@example.com
Developmental Psychology Copyright 2007 by the American Psychological Association
2007, Vol. 43, No. 6, 1579 –1586 0012-1649/07/$12.00 DOI: 10.1037/0012-16126.96.36.1999
etc.). We decided this phenomenon was worthy of systematic
study based on both the relatively high frequency with which
children in a pilot sample were identified as having EIIs and on the
parents’ descriptions of the impact of those interests on the every-
day lives of the children and their families.
A large literature exists on children’s interests in general and the
interrelations between interests and intelligence, learning, atten-
tion, conceptual development, and expertise. (See, for example,
work by Krapp, 2002; Renninger, 1992; Renninger, Hidi, &
Krapp, 1992; Renninger & Wozniak, 1985). Two lines of research
on preschool children’s interests are of particular relevance here.
One comprises detailed case studies of a small number of young
children whose intense fascination with dinosaurs and birds led
them to acquire remarkable levels of knowledge (Chi, Hutchinson,
& Robin, 1989; Chi & Koeske, 1983; Johnson & Mervis, 1994;
Johnson, Scott, & Mervis, 1997). Those reports focus on the
organization of the conceptual structures of these young experts in
their domain of expertise and its impact on their subsequent
acquisition of further domain-related knowledge. In a recent short-
term longitudinal study based on parent reports, 20% of a large
sample of 4-year-old children were classified as having sustained
intense interests in conceptual (knowledge-related) domains (John-
son, Alexander, Spencer, Leibham, & Neitzel, 2004).
Gender differences were found in both these lines of research.
Johnson et al. (2004) noted that 71% of the dinosaur and bird
experts in the expertise studies were boys. In their own large study
of 4-year-olds, 86% of the 42 children identified as having an
intense interest in a conceptual domain were boys. Girls were most
often interested in pretend play, dolls, and art-related activities.
The preponderance of boys with intense interests in conceptual
domains is consistent with Baron-Cohen’s (2002, 2003) character-
ization of males as “systemizers.” Systemizing involves a very
narrow focus of attention on trying to understand and organize a
Two main goals underlie the present research. The first was to
systematically document the existence of EIIs in very young
children and to provide a rich description of the phenomenon. The
second was to examine the relation between gender and the inci-
dence and nature of EIIs early in life. Our pilot work suggested that
EIIs often emerge quite early, consistent with the fact that 70% of
the parents of 5- to 9-year-old dinosaur experts in research by
Johnson and Eilers (1998) indicated that their child’s intense
interest in dinosaurs had been apparent by 3 years of age.
Evidence of gender-related differences in preferences in infancy
suggest that related differences might appear in EIIs. For example,
12-month-old boys look longer at nonsocial stimuli (e.g., moving
cars) than at social stimuli (e.g., people talking), whereas girls
show no strong preference (Lutchmaya & Baron-Cohen, 2002). By
18 months, infants show visual preferences for gender-stereotyped
toys, with boys looking longer at pictures of vehicles and girls
looking longer at dolls (Serbin, Poulin-Dubois, Colburne, Sen, &
Eichstedt, 2001). Further, 18-month-old girls associated these
gender-stereotyped toys with boys’ and girls’ faces, indicating
some awareness of gender stereotypes.
The specific questions addressed in the research reported here
include the following: (a) How common are EIIs among very
young children? (b) Are there gender differences in the incidence
of such interests? (c) At what age do EIIs emerge? (d) What is the
origin of very early EIIs; specifically, to what extent do they
emerge spontaneously? (e) What is the content of EIIs? (f) What
kinds of activities are inspired by young children’s interests? (g)
How do parents and others react to their children’s EIIs? (h) How
long do they persist?
Parents provided information about the interests of 177 children
(84 boys, 93 girls). At the time of the parents’ participation, their
children were between the ages of 11 months and 6 years (mean
age ⫽ 35.1 months). The parents were recruited from all parents
whose children had participated in a variety of different studies in
two different laboratories.
This approach helped ensure that the
sample was not biased toward parents who might choose to par-
ticipate because their children had intense interests. The children
had initially been identified primarily from records of newspaper
birth announcements, and the sample was predominantly White
and middle class.
With the goal of identifying the prevalence, content, and nature
of EIIs in young children, the research progressed in three phases:
(a) initial parent questionnaires, (b) follow-up phone interviews
with a subset of parents, and (c) ratings of intensity of interest by
two coders. Full information on all materials and analyses can be
found in the supplemental materials.
Parent questionnaires. The first step in this research was to
give parents a 15-item questionnaire designed to identify children
with exceptionally strong interests. The questionnaire asked par-
ents to respond regardless of whether their child did or did not
have an intense interest. In an effort to communicate what was
meant by “extremely intense interests,” examples from our pilot
research were described.
The initial item asked whether the child had ever had an intense
interest of any kind. Parents who answered affirmatively com-
pleted the remaining questions. Table 1 gives examples of some of
the questions to which parents responded. Because we were inter-
ested in EIIs, parents were asked to describe only the most intense
interest their child had ever had. Parents identified 116 children
(66% of the original sample) as currently or previously having an
Parent interview. To get a richer sense of the nature of their
children’s interests, parents of all 116 children identified as having
or having had an intense interest were interviewed by telephone
(mean delay ⫽ 6.5 months, range ⫽ 1–11 months). In this semi-
structured interview, they were asked to provide detailed informa-
tion about their child’s interest. Audiotapes of the phone inter-
views were transcribed verbatim.
Ratings of parent interviews. Next, two raters independently
rated the transcripts of all 116 interviews using a 5-point intensity
The laboratories were located at the University of Illinois and the
University of Virginia. There were no differences in participant character-
istics or information reported as a function of location.
No further demographic information was obtained from parents of
of interest scale (1 ⫽ moderate interest;5⫽ extremely intense
interest). Gender information (in the form of names and pronouns)
was present in the transcripts. In making their global ratings, the
raters explicitly took into account the duration of the interest, the
number of different contexts (e.g., home, school, friends’ homes,
library) in which the interest was exhibited, the number of objects
and activities in the category of interest, and the extent to which
the child’s interest was noticed by others (relatives, friends,
friends’ parents, teachers). Interrater agreement on the ratings was
very good (quadratic weighted kappa ⫽ .80). A conservative
criterion was adopted for classifying children as having an EII:
Both raters had to give the child a score of 3 or above (meaning
there was 100% agreement between the raters with respect to the
identification of EIIs).
For 66% of the children rated as having an EII, the interest was
currently active at the time of the parent interview. There were no
differences of any sort between the parent reports on children who
had a current versus a prior interest. The similarity in the parents’
reports for current and past interests suggests that children’s in-
tense interests are salient and memorable to their parents.
Results and Discussion
Prevalence of Children’s EIIs
Figure 1 shows the distribution of children in each of the three
intensity-of-interest categories. The parents of 61 children (18
boys, 43 girls) of the total sample of 177 indicated on the ques-
tionnaire that their child did not have any particularly strong
interests. Parents of 65 children (28 boys, 37 girls) reported that
their child did have an intense interest, but the child’s interest was
classified as “moderate” based on our ratings of 1 or 2 for the
interview transcripts. The remaining 51 children (38 boys, 13
girls)—29% of the entire sample— had scores of 3 or above and
were categorized as having EIIs.
As Figure 1 clearly shows, the majority—75%— of the children
with EIIs were boys. This difference was significant,
(df ⫽ 1) ⫽
12.26, p ⬍ .0001, phi ⫽ .49. Moreover, boys’ EIIs were rated as
more extreme (M ⫽ 3.88) than were girls’ (M ⫽ 3.33), t(46) ⫽
3.77, p ⬍ .001, Cohen’s d ⫽ .98.
Examples of Children’s EIIs
To provide a clear sense of the nature and fervor of these young
children’s EIIs, Table 2 presents detailed summaries of six parent
reports. These examples typify the general nature and range of
EIIs, their emergence, the types of behaviors that provide evidence
of the interests, and the reaction of families and others to them.
Emergence of Children’s EIIs
According to the parents’ reports, the mean age of emergence of
the children’s EIIs was 18 months, with an age-of-onset range of
3– 42 months.
Of particular note, 37% (n ⫽ 19) of the interests
were reported to have appeared within the first year of life, and
90% had emerged by 24 months. There was no gender difference
in the age at which interests first appeared (girls M ⫽ 17.9 months,
boys M ⫽ 18.4 months), and the intensity ratings did not differ for
EIIs emerging before (M ⫽ 3.6 months) and after (M ⫽ 3.8
months) 18 months of age.
In most cases (78%), parents did not report any specific event
marking the onset of an EII. For example, one mother reported that
her son had “always been interested in trucks; it has just always
been there.” Another said that her son “always gravitated to [balls]
and played with them.” Yet another mother said her daughter’s
The two raters assigned exactly the same score to 83% of the tran
scripts. Coders were not blind to the child’s gender for two reasons.
Initially, we had no expectations regarding gender differences in the
incidence of EIIs. More importantly, it would be difficult if not impossible
to eliminate gender information by blocking out children’s names and
pronouns from the transcripts. Virtually anyone reading the highly gender-
stereotyped reports would almost certainly draw inferences about the
One mother reported that her child’s EII was first apparent at 3 months.
Although it is possible that this account was accurate, it was so much
earlier than other reports that we took the conservative action of removing
it from the computation of the mean age of onset of EII.
Figure 1. The number of boys and girls identified as having no intense
interests, moderately intense interests, and extremely intense interests. The
“None” classification was based on parents’ initial responses to the ques-
tionnaire. The other two categories, “Moderate” and “Extreme,” were
based on the two coders’ assessments of the transcripts of the parent
Example Questionnaire Items for Four Question Categories
Question category Example questionnaire items
Onset of interest To the best of your memory, at what age did your
child’s interest start?
Are you aware of any object/event that triggered
Nature of the
Describe what your child does now which shows
Family response What was your initial reaction to your child’s
Did you or others do anything to
encourage/discourage the interest?
Decline of interest Does your child still have the intense interest?
What made you aware it was declining?
emerging interest in dressing-up “didn’t start all of a sudden; there
wasn’t a single precipitating event.”
These parents reported a variety of behaviors that first made
them aware of their child’s EII in an object or activity. For
example, a 9-month-old girl with an interest in balls would pick up
anything spherical and roll it around, showing no interest in any
other toys. Another little girl with an intense interest in books had
been easily soothed when read to at 6 months of age. Parents often
reported that their very young child would indicate his or her
interest by pointing excitedly to objects of fascination. This was
frequently reported for boys with extreme interests in cars, trains,
and airplanes. Several parents reported that the object of their
children’s desire was among their first words.
In contrast, some parents (22%) could pinpoint precisely the
origin of their child’s interest—for example, to a video for interest
in the Blue Angels, the fighter pilot squadron of the U.S. Navy, or
an outing for the interest in U.S. presidents. Another mother
reported that her son’s interest in dinosaurs “started out with one
book and [some toy] dinosaurs that a friend of mine sent.” A boy’s
intense interest in the Wizard of Oz began when he saw the movie
on a video that his older sister was watching.
Content of Children’s EIIs
Each child’s EII was classified into 1 of 11 content categories.
As shown in Figure 2, the content of children’s intense interests
ranged from highly stereotypical to wholly idiosyncratic.
Many of the EIIs involved ordinary items, such as vehicles,
balls, books, dolls, and dinosaurs. The miscellaneous category
(n ⫽ 5) included infrequent items—tea sets, flags, tools, puzzles,
and the Wizard of Oz. There were also some highly idiosyncratic
interests (n ⫽ 6), such as the Blue Angels (see Table 2). Table 3
provides brief descriptions of the five other idiosyncratic interests
reported: pouring liquids; bodies and injuries; U.S. presidents;
Characteristic Examples of Extremely Intense Interests
interest Parent descriptions of their children’s intense interests
Vehicles A 2-year-old boy had an extremely intense interest in vehicles. From about 9 or 10 months of age, he was captivated by anything that
resembled a wheel or moved in a circular motion. He would excitedly point out wheels or wheel-like objects, including automobile
wheels, wheels on a teacart, rotating ceiling fans, sunflower pinwheels, circular patterns on rugs, and so on. He also searched for
wheels in books, magazines, and on television. He collected wheels, circular objects, and cars. Over time, his interest in wheels
became more focused on vehicles—he would watch the traffic pass by, notice cars in parking lots, ask to stop to look at heavy
equipment, and spend hours every day playing with toy cars.
Trains A 4.5-year-old boy’s interest in trains originated from an early focus on the pattern of train tracks themselves. From about 18 months
of age, he would point out anything that resembled train tracks—car tracks in the sand at the beach, fences, stitching on clothing,
and even zippers. After he received a Thomas the Tank Engine railroad set for his second birthday, he played with it for hours
every day. He even slept with his trains. He watched train videos that his parents and others bought for him “countless times.” The
local librarian knew of his interest and saved books about trains for him to check out on his weekly visit.
Dinosaurs A 4-year-old boy’s interest in dinosaurs began when he was 18 months of age. He constantly looked through books (fiction and
nonfiction) about dinosaurs, identifying and comparing them. He peppered his parents with detailed questions about dinosaurs—
how they lived, what they ate, how they hunted, and so on. He spent hours playing with hundreds of plastic dinosaur figurines,
organizing them into elaborate scenes. He also drew countless pictures of the different types of dinosaurs. The boy’s mother was
supportive of his interest and learned a lot about dinosaurs herself. Twice the whole family drove 120 miles to visit the Natural
History Museum in Washington to see and learn more about dinosaurs.
Dressing up A father of a 4.5-year-old girl reported that his daughters’ intense interest in dressing up had begun about 2 years earlier when she
was 2.5 years of age. Around this time, the little girl insisted on wearing only skirts and dresses (absolutely no trousers) and began
dressing up on a regular basis; after preschool, she would come home and immediately change into a costume, usually a
cheerleading outfit or a princess gown, which she accessorized with jewelry and fancy shoes. She spent time looking through
catalogs for dress-up costumes. She was also interested in what other people wore, be they characters in picture books, on
television, or in real life, and would comment as to whether or not she liked their clothing and accessories. Friends and family
gave her so many dress-up costumes as gifts that a footlocker was purchased to hold her collection.
Blenders One boy’s intense interest in blenders first emerged around 18 months, when he insisted “at least ten times a day” that his parents lift
him up so he could see the blender on the kitchen counter. When his parents bought him a toy blender, it became his “constant
companion”; he took it everywhere and even slept with it. He began asking to see blenders when visiting friend’s homes. At the
peak of his interest, around 2.5 years of age, his interest broadened to include other kitchen appliances—food processors, mixers,
toasters, and coffeemakers. He started making up to 25 drawings a day of blenders and kitchen appliances, many with faces on
them. Eventually, his parents replaced his toy with a real one (less the motor and blade) that they found in a garage sale. This
boy’s parents knew their son’s interest was quirky and unusual, but they thought it was cute and were supportive of it for the 2
years it lasted.
Blue Angels One of the more unusual interests—both in content and origin—was that of a 3-year-old boy who developed an extremely intense
interest in the Blue Angels—the fighter pilot squadron of the U.S. Navy. The boy was 30 months of age when he was watching a
video about trains with his mother. It contained a short clip of the Blue Angels flying in the background. He became extremely
excited and “started running around the room in circles squealing.” He insisted on viewing the clip so many times over the next 6
months that it wore out. He also began to ask questions and talk constantly about the Blue Angels. When his parents bought him a
toy Blue Angels plane, it became his “constant companion” for months. He would show it to strangers, telling them that he was
going to be a Blue Angels pilot when he grew up. His parents found the Blue Angels Web site and bought him a Blue Angels
uniform, a DVD, and posters for his bedroom. When wearing his uniform in public, he was thrilled to be saluted by former
military personnel. He learned the Blue Angels song and sang it constantly—so much so that his teacher reported that other
children in his class had also begun singing it.
inventing and building; and brooms, brushes, and mops. The
parents’ accounts of these idiosyncratic intense interests indicated
that they all originated from the child and that there was no initial
encouragement from others.
A particularly striking finding is the gender-stereotyped nature
of the young children’s interests. Over half (57%) of the EIIs fell
into commonly observed gender-stereotyped categories (e.g., Mac-
coby, 1998; O’Brien & Huston, 1985): Fully half (50%) of all the
EIIs reported for boys were for vehicles, trains, and machines, and
another 27% were for balls, dinosaurs, and tools. Nearly half
(46%) of the girls’ intense interests also involved gender-
stereotyped activities (clothes/dressing up, babies, tea sets). These
gender differences in the content of EIIs were not related to the age
of emergence of the interests.
Activities Indicative of Children’s EIIs
The nature and extent of the activities that children engaged in
on a daily basis demonstrate that their interests loomed large in
their lives (see Table 4). Parents reported that the children were
“constantly” on the lookout for objects related to their interest.
They noticed and pointed out not only salient exemplars, such as
cars driving by, but also relatively obscure instances of their
interest (for example, tiny pictures of cars on cracker boxes).
Parents also reported that the children constantly talked about
the object of interest. They also asked endless questions, indicating
an active effort to learn more about the topic. Many parents
indicated that, as a result, their children acquired substantial
knowledge in their interest category. Parents further reported that
the children spent considerable time every day interacting with the
objects or replica objects of interest.
Family Reactions to Children’s EIIs
As suggested by the examples in Table 2, the vast majority
(92%) of parents reported that they reacted positively to their
child’s EII and actively supported it. They bought the objects or
replicas that their child was interested in, as well as relevant books
and videos. Parents also reported spending time in a range of
activities related to their child’s interest. For example, one mother
whose daughter was intensely interested in books spent hours
reading aloud every day, and the pair made several trips to the
library each week. Another mother reported that she and her son,
who was intensely interested in lawnmowers, would regularly
walk around the neighborhood together to watch neighbors mow-
ing their lawn. Others scoured the neighborhood for construction
sites with heavy equipment.
Some children’s extreme interests became disruptive, resulting
in limits being instituted. In one case, a little boy’s extreme interest
in trains became a problem at preschool. The child became ob-
sessed with a table with pictures of Thomas the Tank Engine trains
on it. His mother said that “he almost became a slave to the table”
and stood guard to prevent other children from playing there. It
was causing such a problem that the teacher ended up putting the
table in storage. Another boy constantly pretended to be a dinosaur
Figure 2. Categorization of girls’ and boys’ intense interests.
Brief Descriptions of Five Intense Interests Categorized as Idiosyncratic
Intense interest Description of interest
Pouring liquids One little girl’s idiosyncratic intense interest was with pouring liquids—she was constantly pouring sauces, shampoos,
perfumes, water, and other drinks from container to container. So constant was this activity that she was banned from
visiting the next-door neighbors for repeatedly creating messes by her pouring.
Another girl showed a very unusual intense interest in bodies and injuries. Starting at about 4 years, she was fascinated with
anything health related. She was constantly asking how the body worked and noticed whenever anyone had an injury
(‘owie,’ ‘boo-boo’) or was wearing a band-aid.
U.S. presidents One young boy was intensely interested in the U.S. presidents. He noticed a relief of three Virginia presidents (Jefferson,
Madison, and Monroe) and immediately became fascinated with who these men were and what they did. His mother
described the achievements of the presidents, and her son continued to ask questions about them. He showed a great interest
in the 1996 presidential election and collected various kinds of presidential memorabilia.
A boy with an intense interest in inventing and building was constantly inventing and constructing imaginative objects from
materials found around the house; egg cartons and string, for example, were fashioned into a flying machine, accompanied
with an elaborate explanation of how it worked. He created similar kinds of things several times a day.
One little boy was extremely fascinated by brooms, mops, rakes, hairbrushes, toothbrushes, and vacuum cleaner attachments.
Because of his obsession with these objects, his mother bought him his own broom, hairbrush, and toothbrush that he could
use any time. She then locked the other brooms, rakes, and vacuum in a closet so he could only use them under supervision.
Even the other hairbrushes and toothbrushes had to be secured in an out-of-reach cupboard to keep him from playing with
Note. The sixth idiosyncratic interest, which concerned the Blue Angels, is described in Table 2.
roaring and clawing at other children in his preschool. When some
mothers complained to the teacher that it was upsetting their
children, the child was forbidden to pretend to be a dinosaur at
Only four parents reported not actively supporting their child’s
interest. These interests included pouring liquids; fans and air
conditioners; bodies and injuries; and brooms, mops, and vacuums.
These mothers indicated that rather than actively discouraging the
interest, they generally tolerated and at times reluctantly indulged
their child’s interest. For example, the mother whose 5-year-old
daughter had an extremely unusual interest in bodies and injuries
would occasionally agree to stop the car so they could examine
road kill. The mother whose son was fascinated with fans would
reluctantly allow him to spend time watching the air conditioner
fans and would sometimes indulge his requests to turn the bath-
room fan on and off.
Duration of Children’s EIIs
The EIIs of the young children in our sample were quite long
lasting. At the time of the phone interview, their interests were
reported to have lasted from 6 to as long as 36 months, and the
mean duration of the ongoing EIIs was 22 months (boys M ⫽ 21.4
months; girls M ⫽ 23.1 months). There were no apparent differ-
ences in the persistence of very early versus later emerging inter-
ests. The most salient result was that these young children had
been preoccupied with their interest category for a large portion of
The research reported here provides initial documentation and
preliminary information about the emergence very early in life of
EIIs in particular categories of objects and activities. This striking
phenomenon is not rare: Nearly a third of the children in our
sample developed interests that preoccupied them for anywhere
from a few months to years. Some children became so focused on
one interest that it dominated many aspects of their life—what they
thought about, talked about, looked for, and did.
Three aspects of our results suggest that EIIs typically originate
with the child rather than as a result of influence by other people.
First, more than a third of the EIIs were reported to have emerged
in the first year of life without any parental encouragement or
facilitation. Second, some of the children developed early interests
that their parents found odd (e.g., blenders, vacuum cleaners),
worrisome (e.g., fans), or even repulsive (e.g., injuries and road
kill). The third, and especially intriguing, indicator of the sponta-
neous origin of many EIIs is the existence of a few cases in which
the original basis for the interest seems to be almost wholly
perceptual. For example, although balls are a common, socially
acceptable type of plaything, some of the children with an interest
in balls were described as initially paying attention to anything
spherical in shape, regardless of size, kind (e.g., lamps, walnuts,
gumballs, beach balls), material (e.g., glass, wood, plastic, cloth,
rubber), or function. The most striking passion based on a percep-
tual image is the love of trains that was described to have origi-
nated with train tracks (see Table 2), then spreading to fences and
zippers. One thing in common among these items is that all involve
a pattern of extended horizontal lines regularly intersected by
vertical lines. (The mother did not describe the interest in these
terms.) A fascinating question is how a long-lasting, preoccupying
passion could originate from a meaningless perceptual image;
what causes young children’s attention to be so galvanized by
some particular object or event that it comes to dominate their
Activities Parents Describe as Evidence of Their Child’s Intense Interest
Activity Interest Parent quotes
Cars “He’d find them [vehicles] on cereal boxes, on display stands at the grocery store; he even found them on an
orange juice carton that was half an inch wide and on the back of a Ritz cracker box.”
Wheels/vehicles “When he was younger, anything that moved in a circular motion he considered a wheel. If we go to
Lowe’s, he won’t leave me alone until we get to the area with ceiling fans and walk up and down the
aisle. He will go to anything that has a wheel; whether it’s in a book or in a parking lot. When we’re
driving and he sees something with a wheel, he just becomes visibly more animated and loud.”
Talking about object
or activity of
U.S. presidents “He was very fascinated by the relief of the three presidents at the downtown mall [a prominent sculpture of
Presidents Madison, Jefferson, and Monroe]. He would run down there and look at them and talk about
them and name them. They also have silhouettes of them on the Charlottesville [VA] signs, so every time
we would pass them, he would say: ‘There they are again.’”
“. . .Anything that’s spherical, that she can throw. Walnuts that fall off the tree, balloons, beach balls, all
types and shapes of balls, cloth balls, anything that’s basically round. She tended to go for something that
rolled, and then she’d manipulate it with her hands.”
“He mostly imitates us; trying to rake or mop. He’ll want to mop the floor or brush it. We bought him his
own broom so he can sweep the rug or carpet any time he wants. If he sees something on the floor, he’ll
run and get the broom and sweep it over. We got a new vacuum cleaner that he calls Nu-nu. So we let
him pull it around as much as he wants to because he always wants to vacuum.”
Asking to read
books or watch
videos related to
Dinosaurs “It was the only thing he wanted to watch when he had a video opportunity. We had a couple of books on
dinosaurs, and he found those—they were out all the time.”
Asking parents to
buy items related
Baby dolls “We bought her a zillion dolls. We kept buying more and more dolls because every time we went to the
grocery store, she’d want another one.”
Trains “I bought videos of trains, real trains and model trains. And books on trains.”
The most prominent form of individual difference in EIIs are
gender differences in both the incidence and content of EIIs.
Overall, nearly three fourths of the children in our study who were
identified to have EIIs were boys, and most of their EIIs involved
Both these results are consistent
with Baron-Cohen’s views on gender differences in systemizing
(e.g., Baron-Cohen, 2002).
The gender differences we found contrast with the results for
slightly older children reported by Johnson et al. (2004). They
found that 4-year-old girls and boys were equally likely to have an
“intense interest” in a conceptual domain, differing only in the
specific content of their interests. In our study, boys were twice as
likely as girls to be classified as having an “extremely intense
interest.” Perhaps gender differences occur primarily for the most
extreme level of interests, such that examining only those interests
would reveal a preponderance of boys (and men) at any age.
Over half of the EIIs that emerged in the first 2 years of life were
gender stereotyped. However, implicit knowledge of gender ste-
reotypes is only evident at 18 months for girls and 24 months for
boys (Serbin et al., 2001). This decalage in interests and under-
standing suggests that knowledge about gender does not play a
crucial factor in the initial formation of EIIs.
The preponderance of boys with EIIs reported here is consistent
with evidence that boys are generally more likely to have overrid-
ing specific interests than girls are at 4 years of age (Knickmeyer,
Baron-Cohen, Raggatt, & Taylor, 2005) and that the difference
also occurs in adulthood (Baron-Cohen, Wheelwright, Skinner,
Martin, & Clubley, 2001). A possible biological role in this dif-
ference is reflected in a relation between the tendency for restricted
interests among 4-year-olds and their level of exposure to fetal
One important limitation of the research reported here is that,
because our initial goal was simply to document the existence of
EIIs, parent reports constitute the sole source of data. In further
investigations, converging evidence could come from designing
laboratory tasks to independently assess the strength of very young
children’s interests (e.g., examining performance on tasks using
materials within and outside their interest category).
It would be interesting to learn through future research more
about what— other than gender—sets children with EIIs apart
from other typically developing children. One candidate is intel-
ligence; older children with very strong interests tend to be of
above-average intelligence (Chi, Glaser, & Farr, 1988; Johnson et
al., 2004; Johnson & Eilers, 1998). Another possibility is temper-
ament, with young children with EIIs more likely than others to
engage in repetitive play and to have difficulty shifting attention.
It would also be interesting to know about the relation of the
existence of early EIIs to later interests. Presumably, the likelihood
of long-term relations would depend on the nature and social
acceptability of the interests, in part because parents would provide
more support for more conventional ones. However, continuity
between early and later interests might be manifested primarily in
a general tendency to have intense interests irrespective of content.
Thus, very young children with EIIs may be more likely than the
average child to become devoted hobbyists or collectors as adults,
but the particular focus of their hobby or collecting activity may be
different from what preoccupied them in their first years of life.
The overrepresentation of boys in the group of normally developing
young children with EIIs is also characteristic of individuals with autism
and Asperger’s syndrome (Rutter, 1978; Yeargin-Allsopp et al., 2003).
Furthermore, children in these groups often have very strong preferences
for a circumscribed set of objects or activities, and a strong preference for
construction and vehicle toys is common (Baron-Cohen, 2002). The rela-
tion between EIIs occurring in normally developing children and the
circumscribed interests and preoccupations seen in autism spectrum disor-
ders merits further exploration but is outside the scope of the present
Baron-Cohen, S. (2002). The extreme male brain theory of autism. Trends
in Cognitive Sciences, 6, 248 –254.
Baron-Cohen, S. (2003). The essential difference: The truth about the male
and female brain. New York: Basic Books.
Baron-Cohen, S., & Wheelwright, S. (1999). ‘Obsessions’ in children with
autism or Asperger syndrome: A content analysis in terms of core
domains of cognition. British Journal of Psychiatry, 175, 484 – 498.
Baron-Cohen, S., Wheelwright, S., Skinner, R., Martin, J., & Clubley, E.
(2001). The autism-spectrum quotient (AQ): Evidence from Asperger
syndrome/high-functioning autism, males and females, scientists and
mathematicians. Journal of Autism and Developmental Disorders, 31,
Chi, M. T., Glaser, R., & Farr, M. J. (Eds.). (1988). The nature of expertise.
Hillsdale, NJ: Erlbaum.
Chi, M. T., Hutchinson, J. E., & Robin, A. F. (1989). How inferences about
novel domain-related concepts can be constrained by structured knowl-
edge. Merrill-Palmer Quarterly, 35, 27– 62.
Chi, M. T., & Koeske, R. D. (1983). Network representation of a child’s
dinosaur knowledge. Developmental Psychology, 19, 19 –39.
Gulerce, A. (1991). Transitional objects: A reconsideration of the phenom-
enon. Journal of Social Behavior & Personality, 6, 187–208.
Johnson, K. E., Alexander, J. M., Spencer, S., Leibham, M. E., & Neitzel,
C. (2004). Factors associated with the early emergence of intense inter-
ests within conceptual domains. Cognitive Development, 19, 325–343.
Johnson, K. E., & Eilers, A. T. (1998). Effects of knowledge and devel-
opment on subordinate level categorization. Cognitive Development, 13,
Johnson, K. E., & Mervis, C. B. (1994). Microgenetic analysis of first steps
in children’s acquisition of expertise on shorebirds. Developmental
Psychology, 30, 418 – 435.
Johnson, K. E., Scott, P., & Mervis, C. B. (1997). Development of
children’s understanding of basic–subordinate inclusion relations. De-
velopmental Psychology, 33, 745–763.
Knickmeyer, R., Baron-Cohen, S., Raggatt, P., & Taylor, K. (2005). Foetal
testosterone, social relationships, and restricted interests in children.
Journal of Child Psychology and Psychiatry, 46, 198–210.
Krapp, A. (2002). Structural and dynamic aspects of interest development:
Theoretical considerations from an ontogenetic perspective. Learning
and Instruction, 12, 383–409.
Leonard, H., Goldberger, E., Rapoport, J., Cheslow, B., & Swedo, S.
(1990). Childhood rituals: Normal development or obsessive-
compulsive symptoms? Journal of the American Academy of Child &
Adolescent Psychiatry, 29, 17–23.
Litt, C. J. (1986). Theories of transitional object attachment: An overview.
International Journal of Behavioral Development, 9, 383–399.
Lord, C., Rutter, M., & Le Couteur, A. (1994). Autism Diagnostic Inter-
view—Revised: A revised version of a diagnostic interview for caregiv-
ers of individuals with possible pervasive developmental disorders.
Journal of Autism and Developmental Disorders, 24, 659– 685.
Lutchmaya, S., & Baron-Cohen, S. (2002). Human sex differences in social
and non-social looking preferences at 12 months of age. Infant Behavior
& Development, 25, 319–325.
Maccoby, E. E. (1998). The two sexes: Growing up apart, coming together.
Cambridge, MA: Harvard University Press.
O’Brien, M., & Huston, A. C. (1985). Development of sex-typed play
behavior in toddlers. Developmental Psychology, 21, 866 – 871.
Renninger, K. A. (1992). Individual interest and development: Implications
for theory and practice. In K. A. Renninger, S. Hidi, & A. Krapp (Eds.),
The role of interest in learning and development (pp. 361–396). Hills-
dale, NJ: Erlbaum.
Renninger, K. A., Hidi, S., & Krapp, A. (1992). The role of interest in
learning and development. Hillsdale, NJ: Erlbaum.
Renninger, K. A., & Wozniak, R. H. (1985). Effect of interest on atten-
tional shift, recognition, and recall in young children. Developmental
Psychology, 21, 624 – 632.
Rutter, M. (1978). Diagnosis and definitions of childhood autism. Journal
of Autism and Childhood Schizophrenia, 8, 139 –161.
Serbin, L. A., Poulin-Dubois, D., Colburne, K. A., Sen, M. G., & Eichstedt,
J. A. (2001). Gender stereotyping in infancy: Visual preferences for and
knowledge of gender-stereotyped toys in the second year. International
Journal of Behavioral Development, 25, 7–15.
Winnicott, D. W. (1953). Transitional objects and transitional phenomena;
a study of the first not-me possession. International Journal of Psycho-
Analysis, 34, 89 –97.
Yeargin-Allsopp, M., Rice, C., Karapurkar, T., Doernberg, N., Boyle, C.,
& Murphy, C. (2003). Prevalence of autism in a U.S. metropolitan area.
Journal of the American Medical Association, 289, 49–55.
Received November 4, 2005
Revision received March 24, 2007
Accepted April 11, 2007 䡲