Young Children's Recognition of
Commonalities between Animals and Plants
Kayoko Inagaki
Chiba University
Giyoo Hatano
Keio University
INAOAKI, KAYOKO, and HATANO, GIYOO. Young Children's Recognition of Commonalities between
Animals and Plants. GHILD DEVELOPMENT, 1996, 67,2823-2840. In 4 experiments, we examined
whether young children have grasped commonalities between animals and plants as one of the
essential components of an autonomous domain of biology. Experiment 1 revealed that by age
5, children distinguished both animals and plants from nonliving things in terms of growth (i.e.,
changes in size over time). Experiments 2 and 2A indicated that a considerable number of
5-year-olds, when given brief vitalistic descriptions about properties of all living things, constrained inductive projections of these properties using the category of living things. They attributed not only growth but also taking food/water and being taken ill to both animals and plants
only. In Experiment 3, when 5-year-old children were asked directly whether plants or nonliving
things would manifest phenomena similar to those observed for animals, they responded affirmatively for plants and could offer specific phenomena for growth, feeding, and aging/dying in
support of their answers (e.g., watering for plants as analogous to feeding for animals). Overall,
contrary to Carey, children as young as 5 years have an integrated category of living things. The
possibility that early biology is established around taking food/water and growth is discussed.
Are young children able to distinguish
living from nonliving things? This is a critical issue in the recent debate over whether
young children possess an autonomous domain of biology. Carey (1985) claims that it
takes 9 or 10 years for children to acquire an
intuitive biology. As supporting evidence for
her claim, she cites that young children do
not possess an integrated concept of living
things that includes both animals and plants
^
Previous studies that examined the distinction between animals and nonliving
things have shown that even preschool children can distinguish animals from nonliving
things in terms of the ability to make selfinitiated movements (e.g.. Bullock, 1985;
Massey & Gelman, 1988), the possession of
specific, primarily observable properties
(Gelman, Spelke, & Meek, 1983), or natural
transformations over time (Rosengren, Gelman, Kalish, & McGormick, 1991). However,
studies that examined whether young children distinguish living kinds (including animals and plants) from nonliving things have
provided conflicting results,
™,
n j .
i. i
^ ^i ^
^hose findings which suggest diat
y^^f.^ children lack the living-nonliving dis*''i^':\°" ^ ^ ^ ^ ^ ^ ^ obtained m studies in
^^^'^^ children were asked whether ani^^^f' P'.'^"*!' and inanimate objects .are alive.
A classic study by Piaget (1929) indicated
that children come to attribute life status to
both animals and plants only in late childhood. More recently, Richards and Siegler
(1984), using the rule assessment procedure,
revealed that less than 20% of 4- and 5-yearolds and 50% of 6- and 7-year-olds judged
both animals (including humans) and plants
to be alive. Richards and Siegler (1986) also
reported that when asked for characteristics
of living things, children 7 years of age and
younger named properties which are true
This research was supported in part by grants-in-aid for Scientific Reseaich from the Ministry of Education to the first author (No. 05610095, No. 07610114). We are grateful to the children
and teachers whose cooperation made these experiments possible. We also thank Keigo Takahashi, Head of Dokanyama Kindergarten, for making the participants available, Hiroko Kondo
for her able assistance in conducting the experiments, and John Coley and three anonymous
reviewers for valuable comments on an earlier version oif this article. Requests for reprints should
be sent to Kayoko Inagaki, Faculty of Education, Chiba University, 1-33 Yayoi-cho, Inage-ku,
Chiba-shi, Chiba 263 Japan.
[ChildDevelopment, 1996,67,2823-2840. © 1996 by the Society for Research in Child Development, Inc.
All rights reserved. 0009-3920/96/6706-0016$01.00]
2824
Child Development
only of animals but not of living things in
general. Stavy and Wax (1989) found that
only 30%-60% of Israeli children aged 6-11
years classified plants correctly as living
things.
Another piece of evidence against
young children's possession of the livingnonliving distinction was offered by Carey's
(1985) study, which examined whether children's induction of a given property would
be constrained by biological categories. Sixyear-old children were taught a novel property that was beyond their understanding
about dogs and bees, about dogs and flowers,
or only about flowers (e.g., that X had golgi).
The children were then asked whether other
animate and inanimate objects (including astronomical ones) also would have it. The results provided no evidence that the concept
of living things constrained their induction.
Children who were taught about dogs and
flowers tended to attribute golgi more
widely than those who were taught about
dogs and bees or just flowers, but they often
overattributed the novel property even to inanimate objects.
In contrast, a number of studies have reported results indicating that young children
have acquired the living-nonliving distinction and recognize commonalities between
animals and plants. These flndings have
been obtained when children were asked to
make attributions of somewhat familiar
properties to a variety of entities. Hatano et
al. (1993) found that 5- and 6-year-old children in Israel, Japan, and the United States
attributed such properties as "grow" and
"die or wither" to animals and plants, but
not to inanimate things. In the Stavy and
Wax (1989) study, most children below 11
years failed to attribute to plants the properties of breathing, eating, and reproduction,
but they correctly attributed the property of
growth to plants; many children answered
that plants grew, but were not alive. Keil
(1983) reported that kindergartners correctly
applied the predicate grow to both animals
and plants, though they applied the other
animal-plus-plant predicates, such as alive,
sick, and starve, to animals only.
Those studies that dealt with an entity's
reactions in specified situations have also reported that young children make differential
predictions and/or explanations for animals
and plants versus nonliving things. For example, Inagaki and Hatano (1987) found that
when 5- and 6-year-oIds were asked to predict behaviors of an animal or a plant in situ-
ations involving four biological phenomena
(e.g., growth, spontaneous recovery, etc.),
the children relied on personification (the
person analogy) for making predictions for
the animal and the plant, but not for a stone,
a representative inanimate object. Backscheider, Shatz, and Gelman (1993) focused
on the ability of living kinds to heal through
regrowth. Preschool children were told that
animals, plants, and artifacts had been damaged and were then asked whether the objects could heal through regrowth or could
be mended by a person. The results indicated that children recognize that both animals and plants can recover through regrowth, while artifacts must be fixed by a
person. Springer and Keil (1991) found that
4- and 5-year-old children differentiated animals and plants from artifacts in terms of
mechanisms of color acquisition. That is,
these children preferred natural mechanisms of inheritance for animals and plants,
whereas for artifacts the children recognized
the importance of human intervention. Celman and Kremer (1991) reported similar
findings for the distinction between natural
kinds (such as a rabbit and a flower) and artifacts.
Neither the results supporting young
children's understanding of the livingnonliving distinction nor those denying it
are conclusive. On the one hand, children's
failures to make this distinction might be
due to the ambiguity of the questions posed
to them. The term "alive" is especially complex and contains multiple definitions that
young children may find confusing. Alternatively, the failure may be attributed to low
retrievability of the concept of living things.
The children in Carey's (1985) study may
not have relied on biological boundaries in
inductive projection, because they may have
failed to activate the concept of living things
in attributing the novel and incomprehensible property of having golgi, not because
they did not possess the concept. Vera and
Keil's (1988) study, which primarily concerned the concept of animals, supports in
part this line of reasoning. They showed that
4-year-olds produced more extended and
more accurate induction of animal properties to various animals when biological contexts were given by brief explanations about
functions of those properties than when no
contexts were provided. The 4-year-olds'
performance with the contexts was comparable to that of the 7-year-olds in Carey's
(1985) study where such contexts were not
given. Giving some information about bio-
Inagaki and Hatano
logical functions of properties may help
young children activate and use the biological categories they possess. To generalize,
because animals and plants are perceptually
so difFerent (e.g., in terms of spontaneous
movement), young children's use of the category of living things requires a context drawing their attention to or a question asking
about such familiar shared biological properties as survival, developmental change, and
reproduction.
2825
often for plants as well as animals, will help
children grasp the commonalities.
In the present research, we performed
four experiments to determine whether children aged 4—5 years have grasped commonalities between animals and plants at the
functional level that can be called biological
and, thus, whether they possess the category
of living things. We also hoped to identify
the biological phenomena based on which
an early recognition of the animal-plant comOn the other hand, it can be claimed monalities is achieved. In Experiment 1, we
that most of the studies supporting young focused on the property of growth, examinchildren's understanding of flie distinction ing whether children differentiated animals
have only shown that children attribute to and plants from nonliving things in terms of
both animals and plants an isolated property growth. This was because, as a basis for the
or that they predict animals and plants will subsequent three experiments, we needed
respond similarly to a single situation. In conclusive evidence that young children
other words, these studies have fallen short recognize growth (i.e., increase in size over
of revealing that children grasp commonali- time) as one of the characteristics animals
ties between animals and plants in terms of and plants share. We extended Rosengren et
a cluster of interrelated properties or behav- al.'s (1991) method, which successfully esiors. We cannot conclude that they possess tablished young children's animal-artifact
a higher-order category of living things, un- distinction to include plants so that the reless they regard animals and plants as shar- sults could reveal children's ability to make
ing at least a few biologically important the living-nonliving distinction.
properties.
In the subsequent three experiments,
Whether the living-nonliving distinc- we directly examined whether children
tion is achieved in early childhood or not, have the category of living things, that is,
how do children begin the difficult job of" whether they can use the category in reasonrecognizing commonalities between the two ing about not only growth but also other revery different ontological classes of animals lated biological properties and behaviors
and plants, without histological and physio- (e.g., taking food/water). In Experiments 2
logical knowledge? What properties or be- and 2A we investigated whether young chilhaviors serve as the basis for the recogni- dren's inductive projection from humans for
tion? The above review suggests that growth properties that both animals and plants share
is one such property, though there has been would be constrained by the category of livno conclusive evidence that even young ing things. In one of the conditions we gave
children attribute growth to a variety of ani- them short biological or vitalistic explanamals and plants but not to inanimate objects. tions of the target properties, which we asIt has also been suggested that children as- sumed would activate the concept of living
sociate growth with feeding or watering. We kinds they might have.
thus assume that growth and growth-related
properties may constitute the core of young
In Experiment 3, we examined whether
children's concept of living things. These young children would grasp consciously
properties may include those that cause some commonalities between animals and
growth, such as taking in energy from food/ plants by requiring them to make analogies
water or even from air, as well as those re- between the two kinds. Specifically, we digarding changes in the life course other than rectly asked the children whether plants or
growth in size, such as being taken ill or be- nonliving things would manifest phenomcoming old and dying. These properties may ena similar to those that were observed for
serve as the basis for children to recognize animals. This would reveal that they could
commonalities between animals and plants, recognize commonalities between animals
to the extent that they are applied to both and plants much more readily than those beanirnals and plants in children's linguistic- tween animals and nonliving things. It
cultural environments. For example, we ex- would also suggest which phenomena or
pect that the properties of growing and dy- properties are bases upon which children
ing or withering, which are seemingly used recognize the animal-plant commonalities.
2826
Child Development
Experiment 1
The purpose of Experiment 1 was to establish that young children can distinguish
animals and plants from nonliving things in
terms of growth. As mentioned above, our
literature survey suggests that growth is one
of the few characteristics that even young
children recognize as being shared by animals and plants. This is supported by daily
observation, too. Children seem to have
learned that animals are born as babies and
become bigger in size (e.g., Rosengren et al.,
1991). Plants, especially flowers, are likely
to grow markedly (i.e., change from sprout
to bloom) in a short period. Though trees
grow in size much more slowly, they often
undergo changes corresponding to the seasons, having tiny fresh green leaves in
spring, growing thick in summer, and so on.
We thus assume that young children characterize plants as "growers," as expressed in
Hebrew (Stavy & Wax, 1989).
We used as a model Rosengren et al.'s
(1991) inquiry procedure in this experiment
but extended it to include plants as well. We
also modified their procedure on four points
to be described below. As an auxiliary aim,
we thus examined whether the results for
animals reported by Rosengren et al. (1991)
would be replicated under our modified,
more controlled conditions.
First, we avoided the use of words implying differences in size, such as "a baby"
and "an adult," and constructed questions
as nearly identical as possible for animals,
plants, and artifacts. In the Rosengren et al.
study the wordings of "an adult" at the time
of choice versus "a baby" at the beginning
of each item, which were used only for animals, may have led the children to differentiate spuriously between animals and artifacts, because such wordings suggest an
increase in size. Second, we asked the children whether an animal, a plant, or an artifact would undergo changes after not only a
long time but also a short time (i.e., a few
hours). Children's false prediction of shorttime growth could be taken as strong evidence of their characterizing animals and/or
plants as growers. Third, we used only same
size-lairger size pairs. In other words, pairs
with a smaller size picture were not used,
because in the Rosengren et al. study even
the youngest children (aged 3 years) understood that neither animals nor artifacts
would become smaller over time. Nor were
larger size pairs involving changes in shape
over time used, because our primary aim
was to assess children's understanding of
how entities change in size over time, not
their knowledge about metamorphosis.
Fourth, to eliminate possible carry-over effects, each child was assigned to one of the
three conditions (i.e., animals, plants, and
artifacts) and was thereby asked about only
one of the three categories.
We predicted that children would understand that both animals and plants become larger as time goes by, whereas artifacts remain constant in size. More
specifically, when asked what would happen
with the target a very long time later, the
children in the plant as well as the animal
conditions would choose a larger object.
They might correctly choose an object of the
same size as the presented target for a-shorttime-later questions or erroneously choose a
larger one because of their (basically correct)
characterization of animals and plants as
growers. On the other hand, the children in
the artifact condition should choose a picture of the same size for both short- and longtime-later questions. Artifacts were used as
representatives of nonliving things here, because watching them seemed more natural
than watching a stone or other nonliving natural kinds, and because in a previous study
the verbal attribution of growth by 4-yearolds did not differ between artifacts and nonliving natural kinds (Inagaki & Hatano,
1993a).
Method
Subjects.—Forty-eight 4-year-olds (mean
age 4 years 6 months, range 4-0 to 4-10) and
48 5-year-olds (mean age 5 years 9 months,
range 5-3 to 6-2), the same nuniber of boys
and girls, served as subjects. They attended
the same kindergarten in Tokyo and were
mostly from lower-middle-class families. An
equal number of subjects in each age group
were randomly assigned to one of the three
entity-type conditions, that is, animals,
plants, and artifacts.
Materials.—The
stimulus materials
consisted of four sets of three animal pictures each, four sets of three plant pictures
each, and four sets of three artifact pictures
each. Each picture was depicted on a 10 x
11 cm piece of cardboard. Two of the three
pictures in each set were identical, and the
third item was either larger (i.e., size
change) or both larger and different in shape
(i.e., size and shape change). The four sets
of animals, those of plants, and those of artifacts each consisted of two size-change sets
and two size-and-shape-change sets. A list of
Inagaki and Hatano
2827
TABLE 1
ITEMS USED IN EXPERIMENT 1
Animal Stimuli
Size change:
Alligator
Penguin
Size and shape change:
Dog
Hen
Plant Stimuli
Artifact Stimuli
Fir tree
Pine tree
Teddy bear
Pair of scissors
Sunfiower
Hyacinth
Gup and saucer
the animals, plants, and artifacts in each set
type is presented in Table 1. Examples of
size-and-shape-change sets are shown in
Figure 1.
Procedure.—In each entity-type condition, those sets involving only changes in
size were presented prior to those including
changes in both size and shape. This was
done because pilot testing indicated that
when we began with artifact sets containing
changes in size and shape, several 4-yearolds chose a larger picture, and some of them
referred spontaneously to magic.
Each child was tested individually in a
small room in the kindergarten. He or she
was presented with a standard stimulus, a
picture of a flower bud (or a small tree/a
young animal/a new artifact), and was then
asked to choose which of the two other pictures would show the plant/animal/artifact
a few hours later and several months/years
later. One of the pictured stimuli to be chosen was identical to the standard, and the
other pictured item was either larger or
larger and different in shape. These two pictures were placed below the standard stimulus, one to the left and one to the right, with
left-right position randomly determined.
Instructions.—What follows is an example set of instructions for the tree stimuli in
the plant condition. "This is a picture of X.
Taro saw this X when he arrived at the kindergarten in the morning. If he sees it again
when he leaves the kindergarten for home,
which of these trees will he be able to see?";
"Then, if he sees it Once again after a very,
very long time, many years later, which of
these trees will he be able to see?" For the
flower sets, "after a very long time, in summer" was used instead of "after a very, very
long time, many years later."
Instructions for all sets in the other two
conditions were almost the same as those for
the tree sets described above except that the
situations in which Taro saw the target stim-
Bag
uli were different and thus the wordings
were changed accordingly. For example, a
zoo was used for the animal sets instead of
the kindergarten. For the artifact sets, the
experimenter said, "Taro put X in the box
and left home to play outside," and actually
put the picture of X in a small cardboard box,
which was 2 cm in depth; its top was left
open so that the child could see the picture.
We used the box for the artifact sets as in the
main experiment in Rosengren et al. (1991),
because their Experiment IA results indicated that the use of the box did not influence children's responses.
Results and Discussion
The children's choice responses were
Same size-Same size (SS) for the two questions of "a few hours later" and "several
months/years later," Same size-Larger size
(SL), Larger size -Larger size (LL), or Larger
size-Same size (LS). Table 2 shows the frequencies of these four types of responses for
animals, plants, and artifacts in each age
group. Both 4- and 5-year-olds made SL responses most often for both animals and
plants, whereas they made SS responses
most often for artifacts. That is, for animals
and plants the children predicted changes
in size (and also in shape) after a long time
(though not after a few hours), whereas for
artifacts they expected no changes in size
over time. This tendency was found clearly
among the 5-year-olds. They made SL responses 69% of the time (44/64) for animals
and 78% of the time (50/64) for plants. In
contrast, they seldom made SS responses for
animals or plants, but did 81% of the time
(52/64) for artifacts. Thus the average percent correct across these three types of entities was 76% among the 5-year-olds. Though
the average among the 4-year-olds was only
57%, and they made a considerable number
of responses other than SS (38/64) for artifacts, they made few SS responses for animals and plants. There was no difference between responses for the size-change sets and
2828
Child Development
Standard stimuius
Animai set
Ciioice stimuli
Piant set
Artifact set
FIG. 1.—An example set of standard stimulus and choice stimulus cards for animals, plants, and
artifacts (size-and-shape-change set).
those for the size-and-shape-change sets for
either animals, plants, or artifacts, though
any potential difference may have been reduced by the covarying order effect.
The children made some LL responses,
especially for plants. This result was probably due to the overestimation of the growing
speed, derived from their characterization of
plants (and sometimes animals, too) as rapid
growers. Another reason for LL responses
may be that these children had difficulty
conceptualizing time; they may have regarded "a few hours" to be equivalent to "a
few months/years." Moreover, considering
that LL responses occurred even for inanimate objects, some children may have had
preference for a larger alternative and/or referred to magical change.
The children also made some LS responses. These responses may have been
produced by children who felt somewhat
compelled to give different answers to the
short-time-after and long-time-after ques-
tions or may be due to some understanding
of the long-term intergenerational pattern of
growth.
For statistical analyses we computed a
"growth score" for each child, giving one
point to an SL or an LL response and zero
to an SS response. We gave zero to an LS
response too, because the nature of this response is ambiguous in terms of growth. The
growth score was entered into a 2 (age: 4, 5)
X 3 (entity type: animals, plants, artifacts)
ANOVA with age and entity type as between-subject factors. A significant main effect was obtained only for entity type, F{2,
90) = 35.17, p < .001. Tukey's post hoc analyses revealed that the growth score was significantly higher for animals (M = 2.75) or
plants (M = 3.34) than for artifacts (M =
0.75), whereas it was not significantly different between animals and plants. There was
no significant age X entity type interaction.
These results indicate that the 4- and 5-yearolds differentiated both animals and plants
Inagaki and Hatano
2829
TABLE 2
FREQUENCIES OF FOUR TYPES OF RESPONSES FOR ANIMALS, PLANTS, AND ARTIFACTS
IN EACH AGE GROUP (Experiment 1)
4 YEARS
TYPES OF RESPONSES
SS response
SL response
LL response
LS response
5 YEARS
Animal
Plant
Artifact
Animal
Plant
Artifact
9
36
6
13
7
37
11
9
37
12
5
10
6
44
2
12
0
50
9
5
52
7
0
5
NOTE.—The total number of responses for each condition was 64 (16 subjects with four
responses per subject). S = same size; L = larger size. Thefirstletter of each two-letter pair
indicates child's response to a-few-hours-Iater question; the second, his or her response to
sevetal-months/years-later question.
from artifacts in terms of changes in size (and
also in shape) over time.
The present results for animals confirm
those reported by Rosengren et al. (1991).
Although the wordings were more comparable between conditions in this study, even
the 4-year-olds clearly differentiated animals from artifacts in terms of growth. As
described above, the 4-year-olds in the present stndy showed responses other than SS
for artifacts at a substantial level. This is consistent with the result that Rosengren et al.
(1991) found for 3-year-old children. The results of our study supported their description that "at least by age 5, children consistendy answer correctly" (p. 1310).
Experiment 2
The results of Experiment 1 revealed
that the 4- and 5-year-old children treated
animals and plants (but not artifacts) as entities changing in size (and also in shape) over
time. These resnlts corroborate, with a more
adeqnate methodology, previous findings
that growth is relatively easy to recognize as
a commonality of animals and plants (e.g.,
Hatano et al., 1993; Stavy & Wax, 1989). As
described earlier, however, these results per
se do not necessarily indicate that the children have a category of living things. To assert that they have afcategoryof living things
we need to show that children recognize
commonalities for other (related) properties
(dying, healing, etc.) as well. The method
used in Experiment 1 is not appropriate for
this purpose, because competing predictions
for these properties may not be represented
pictorially. In Experiment 2, we therefore
adopted another method of inquiry.
In Experiment 2, we used the induction
paradigm, which enabled us to inqnire about
various properties within a short period of
time. Indnctive patterns can illuminate concepts children possess, because the patterns
are generally constrained by the concepts.
However, it should be noted that both "false
negative" and "false positive" conclusions
about the possession of a given concept may
be derived by analyzing the patterns of induction. On the one hand, a concept children possess may not be activated and thus
may fail to affect their pattems of induction.
This is likely to occur when a given property
is phrased using a predicate readily applicable to a part of the concept only. On the
other hand, attributional patterns identical
to those generated by constrained induction
may be obtained when children know specifically which objects possess the target
characteristic. Carey (1985) used totally
novel properties in order to eliminate this
"false positive" possibility. However, as discussed in our introduction, it is possible that
her subjects failed to activate the biological
concept because they could not nnderstand
the functions of novel properties that were
taught to them on the spot.
In our procedure, we employed somewhat familiar properties in the sense that
most children might know that humans have
them. We assumed that although children
might know that humans (including themselves) possess these properties, they would
be uncertain as to which other entities do,
because the properties are not directly observable and because they do not encounter
such entities often. In attributing snch properties, they would thus have to make inferences based on an intuitive grasp of the
functions of these properties. In order to reduce further the possibility of obtaining a
"false negative" result, we followed the
methods of Vera and Keil (1988) and pro-
2830
Child Development
vided half the subjects with a biological context which was expected to trigger their biological knowledge system. Though the effect
of giving a biological context was limited to
animals in Vera and Keil's study, we expected that the effect wonld extend to plants
when properly phrased all-living-things
properties were used. Thus children's
knowledge of a living-nonliving distinction
conld be examined.
More specifically, we investigated
whether children's inductive projection
from humans for not only growth but other
properties wonld be constrained by a living
things category. We set up two conditions:
with biological contexts and without contexts. As biological contexts, we used short
vitalistic descriptions about functions of
properties for a person: that is, those referring to taking in or exchanging vital force or
energy, a notion that children aged 6 years
are supposed to regard as plausible (Inagaki
& Hatano, 1993b). We included among the
target properties being taken ill, eating, and
respiration, in addition to growth, because
these properties are related to the taking in
of or effects associated with vital power. If
giving vitalistic accounts of properties enhances children's nse of the biological category of living things in their inductive projection, it would imply that children
consider both animals and plants to be biological entities with the same underlying
mechanisms.
Method
Subjects.—The subjects were 52 5-yearolds (mean age 5 years 10 months, range 5-1
to 6-4), equal numbers of boys and girls,
from the same kindergarten as the children
in Experiment 1. They had not participated
in Experiment 1. They were assigned either
to the context condition or no-context condition in such a way that the subjects in the
two conditions would be comparable in
chronological age and gender. Here we did
not include 4-year-olds as subjects, because
the resnlts of Experiment 1 indicated that
the 4-year-olds' living-nonliving distinction
was far from perfect, as indicated by their
modest levels of average percent correct.
Procedure.—Each child was individually interviewed in a small room. The children in the context condition were told that
a person had a given property, along with a
short vitalistic explanation abont its function, and then were asked whether a set of
the target objects also had it. Those in the
no-context condition were asked whether
the objects had a given property that a person had, without any explanation about its
function. There were nine target objects,
three each from animal, plant and nonliving-thing categories: squirrel, alligator,
grasshopper, tulip, dandelion, pine tree,
stone, pencil, and chair.
The children were questioned about
four properties: growing, being taken ill,
breathing, and eating. The first two of the
four were properties that animals and plants
share, and the latter two, though some analogous properties could be found among
plants, are applicable to animals alone in
their present phrasing. Each property question was asked abont all the objects before
the inquiry proceeded to another property.
The target objects were given in random order for each subject, but the property questions were asked in a fixed order.
The following are the descriptions of
each property given in the context condition.
The descriptions given in the no-context
condition were the same as those in the context condition, except for the italicized parts,
which were omitted.
1. Grows: A person becomes bigger and bigger, by taking in energy from food and water.
Tben, does X become bigger and bigger?
2. Is taken ill: A person is sometimes taken
ill, because his energy or vital power is gradually
weakened by germs going into his body. Tben, is
X sometimes taken ill?
3. Breatbes: A person breathes in order to
take in vital power from fresh air. Then, does X
breathe?
4. Eats: A person eats food every day. If he
doesn't eat food and cannot take in energy or vital
power from it, he will die. Tben, does X eat something?
Data analysis.—For each of the four
property questions, we counted individual
children's numbers of yes responses to three
instances each of animals, plants and inanimates. When the nnmbers of yes responses
to animals, plants, and inanimates were 3,
3, 0, respectively (yes responses to all three
instances of animals and plants bnt not to
any of the inanimates), we classified this set
of responses as an animal-and-plant pattern.
Similarly, we classified responses of 3/0/0
as an animal pattern, 3/3/3 as an all-things
pattern, and 0/0/0 as a human pattem. When
any of the four patterns defined above could
be obtained by changing one response (yes
to no or vice versa), we also included it in
the corresponding category; for example, 3/
Inagaki and Hatano 2831
TABLE 3
FREQUENCIES O F PATTERNS FOR EACH PROPERTY IN EACH GONDITION (Experiment 2)
PATTERNS
GROWING
TAKEN I I I
BREATHING
G
NG
G
NG
G
NG
12
0
1
0
11
7
11
2
11
5
20
3
15
Animal and plant .... 23
Animal
1
Human
All things
Otbers
1
1
2
5
3
0
6
7
0
0
0
1
3
0
5
EATING
G
NG
11
13
0
0
2
10
14
1
1
0
NOTE.—C means context condition; NC, no-context condition. N = 26 for both context and
no-context conditions.
2/0 or 3/3/1 was an animal-and-plant pattern
and 2/0/0 was an animal pattern. Patterns
not satisfying any of the above criteria were
classified as "others."
Results and Discussion
Table 3 shows frequencies of each attribntional pattem for each property in each
condition. First, we computed the probability of subjects' producing the animal-andplant pattern by chance in order to examine
whether the actual frequencies in Table 3
were produced by children who had a concept of living things. If yes-no responses
were made at random for each of the nine
objects, the animal-and-plant pattern would
be obtained only 10/512 (2*^) times. Thus,
the probability that two or more children out
of 26 would show such a consistent pattem
is below .01. However, in the following discussion, we will adopt the more conservative criterion of more than a quarter (6.5) of
the subjects' falling into the animal-andplant pattern.
In the no-context condition, about half
(46%) the subjects constrained their induction by the category of living things for
growth, and a few did so for being taken ill.
However, in the context condition, the number of subjects who produced the animaland-plant pattem exceeded the above criterion for both living thing properties. A great
majority (88%) of the children showed this
pattern for growth; the difference in frequencies of the animal-and-plant pattern between context and no-context conditions was
significant, x^(l, IV = 52) = 10.58, p < .01.
For being taken ill, seven children in the
context condition and two in the no-context
condition showed this pattern; the difference was marginally significant {p < .07) by
the Fisher's direct probability test.
It should be noted that more than a
quarter of the children in both conditions
showed animal-and-plant patterns for eating,
which was supposed to be an animal property, though animal patterns were in fact
most dominant for it. In answering the
eating question for a plant, nine said, "It
drinks water" without answering yes or no.
These responses (19 in all) were counted as
yes. One child in the context condition explained spontaneously, "(A tulip) takes in
water and nutriment," after he attributed
eating to a plant. This point was examined
further in the next experiment.
In the context condition, more than half
(13) of the 23 children who showed the animal-and-plant pattern for growth indicated
the same pattem at least once for other properties; seven for being taken ill and 10 for
eating. (In the no-context condition four
children showed the animal-and-plant pattem for both growth and eating.) These results strongly suggest that a considerable
number, if not a majority, of the 5-year-olds
possessed a category of animals and plants
combined.
"Others" pattems were fonnd more often in the no-context condition; 17 nocontext children showed one or more "others" patterns for the four properties, whereas
seven context children did so. The difference was significant, x^(l> ^ — 54) = 9.59,
p < .01. This also suggests that providing
a biological context helps children produce
category-based responses by activating children's knowledge. These results and interpretations are consistent with the effect of
the biological context in Vera and Keil
(1988).
In the context condition, more yes responses than in the no-context condition
were given to animals (84.0% vs. 65.4%) and
to plants (64.1% vs. 50.6%), bnt not to inanimates (1.3% vs. 7.1%) for the two all-livingthings properties. This result suggests that
2832
Child Development
the children's biological theory that was exemplified by the vitalistic descriptions given
to humans only covered other animals and
plants and excluded inanimate objects.
Experiment 2A
In Experiment 2, a great majority of the
children in the context condition showed induction patterns constrained by the category
of living things for the property of growth,
whereas fewer than half the children in the
no-context condition showed such patterns.
In other words, a vitalistic causal explanation about growth ("A person becomes bigger and bigger by taking in energy from food
and water") activated the category of living
things that the children already had, because
the explanation given was too brief for children to acquire this category and because
there would not have been any difference in
the frequency of the animal-and-plant patterns between the two conditions if they had
responded based on their knowledge of
whether specific animals and plants grow.
This suggests that children consider taking
food and/or water as necessary for animals
and plants to grow. In Inagaki and Hatano's
(1987) study many of the children who denied the possibility of stopping growth justified their responses by referring to feeding
or watering; for example, "A rabbit becomes
bigger by eating food," or "A tulip becomes
bigger when we water it." The "eating"
property of Experiment 2 was not phrased
in such a way that could be applied readily
to plants. The action verb "eat," which is
applicable only to animals, and the word
"food" as the object of this action, were used
in that question. Nevertheless, as described
earlier, some children hesitated over the response to that question for plants, and in fact
more than a quarter of the children applied
this property to plants as well. This strongly
suggests that many children regard taking
food/water (like growth) as one of the characteristics animals and plants share.
In Experiment 2A, we therefore examined whether children would show induction pattems constrained by the category of
living things in attributing taking food/water
to a variety of entities. In addition, we again
examined whether children would recognize the commonality between animals and
plants as entities capable of being taken ill
by revising the explanation of this property.
The effect of giving the vitalistic explanation
about being taken ill on activating the category of living things was found in Experiment 2 but was relatively small. This may
have been because the description consisted
of a mixture of the vitalistic explanation (a
dominant idea in the endogenous science)
and the germ one (a dominant idea in Western medicine); it may not have represented
accurately enough the biological beliefs that
the children had. Thus we gave children in
the context condition a revised vitalistic description about being taken ill. It explained
illness as a diminution of vital power due to
the loss of balance, not to germs. A question
about defecation, clearly an animal property,
was included as a control item.
Method
Subjects.—Forty 5-year-olds (mean age
5 years 10 months, range 5-3 to 6-2), equal
numbers of boys and girls, from the same
kindergarten as the children in Experiments
1 and 2. They had not participated in either
of these previous experiments. They were
assigned either to the context condition or
no-context condition, with chronological age
and gender balanced.
Procedure.—The procedure was the
same as that used in Experiment 2, except
for the types of property and their descriptions. What follows are the descriptions of
each property used here. The italicized parts
were not presented in the no-context condition.
1. Takes food/water: A person needs water
and/or' food. If he does not take in energy or vital
power from water and/or food, he will die. Then,
does X need water and/or food?
2. Is taken ill: A person is sometimes taken
ill, because his energy or vital power is gradually
weakened when he feels too cold or too hot. Tben,
is X sometimes taken ill?
3. Defecates: A person poops. He gets rid of
matter that is no longer useful inside the body as
feces. Tben, does X poop?
Results and Discussion
Table 4 shows frequencies of each attribution pattern for each property question in
each condition when the data were analyzed
by the same criteria as those in Experiment
2. For the question about taking food/water.
^ We translate the conjunction in Japanese, ya, into "and/or" in English. It is not equivalent
to "and/or" in the logical sense, but it sometimes means "and" and oth^ times "or." Tbis
conjunction is commonly used in everyday conversation and easily understood by young
cbildren.
Inagaki and Hatano
2833
TABLE 4
FREQUENCIES OF PATTERNS FOR EACH PROPERTY IN EACH GONDITION
(Experiment 2A)
TAKING
FOOD/WATER
PATTERNS
G
Animal and plant .... 18
Animal
1
Human
0
All tbings
0
Otbers
1
TAKEN I I I
DEFECATING
NG
G
NG
G
NG
13
2
1
0
10
6
3
9
3
0
5
0
17
3
0
0
0
16
4
0
0
4
2
0
2
NOTE.—C means context condition; NC, no-context condition. N = 20forboth context and
no-context conditions.
if the children answered that a target object
needs either water or food only, we judged
it as a yes response.
they did not simply apply the animal-andplant pattern in an automatic fashion across
all the questions.
For the "taking food/water" question,
90% (18/20) of the children in the context
condition showed animal-and-plant pattems. Sixty-five percent (13/20) of the nocontext children showed such pattems. The
difference in frequencies of animal-andplant patterns between the children with
and without contexts was marginally significant, x^(l, N = 40) = 3.13, p < .10. This
suggests that children tend to recognize animals and plants, but not nonliving things, as
entities needing food/water, and that giving
a vitalistic explanation about taking food/water activates this knowledge.
In the context condition, as opposed to
the no-context condition, more yes responses were given to animals (84.0% vs.
65.4%) and to plants (64.1% vs. 50.6%) for
the two all-living-things properties. Again,
the context had no effect on yes responses
to inanimate objects (0.8% vs. 0.8%). As described earlier, children's biological theories, that were triggered by vitalistic explanations about humans, covered other
animals and plants, but not inanimate objects.
For the "taken ill" question, 10 of the
20 children in the context condition showed
the animal-and-plant pattern, while only
three did so in the no-context condition; the
difference in frequencies between the two
conditions was significant, x^(l; ^ = 40) =
5.58, p < .02. The increased proportion of
the context children who showed attributional patterns constrained by the category
of living things suggests that the explanation
used in Experiment 2A was more plausible
than that used in Experiment 2, though
fewer children showed such pattems for being taken ill than for the taking of food/
water.
The results of Experiments 2 and 2A indicated that giving biological contexts
helped the children extend given properties,
especially growth and taking food/water, to
both animals and plants but not to nonliving
things. This suggests that the biological context activated thd category of living things
that children already had, becanse each description for creating the biological context
took only seconds. However, this result is
not enough for us to assert that young children have consciously grasped commonalities between animals and plants. We dealt
with this issue in Experiment 3.
In the context condition, nine children
showed the animal-and-plant pattern for
both taking food/water and being taken ill.
None of those children, however, demonstrated the animal-and-plant pattern for defecation: Rather, a majority of them correctly
responded with the animal pattern. Thus,
We explored a few alternative methods
of directly asking children about commonalities between animals and plants. The use of
generic terms like animals and plants is desirable (e.g., "What do animals and plants
have in common?") but is not possible with
our subjects, mainly because the term
"plants" {shokubutsu in Japanese) is incom-
Experiment 3
2834
Child Development
(c) growing in size as time passes, {d) becoming older and ultimately dying, (e) overfeeding causing ill health, (/) discarding waste
matter as feces or urine, (g) taking in fresh
air, and {h) being ill-fed. All were phenomena common to advanced animals, but only
growth can be applied to plants without
changing phrasings. In other words, snbjects
were in fact required to find functionally
equivalent phenomena for plants, by mapping between animals and plants. Example
Here, too, we asked children about var- questions for feeding and growing in size
ied "biological" properties or behaviors, in- were as follows (see Appendix for the other
clnding growth and taking food/water, that questions): "A squirrel or an alligator will
they might believe animals and plants share. die if we do not feed it. Do yon think anyWe expected that Experiment 3 would not thing similar to this occurs with a tulip or
only reveal whether children could recog- a pine tree/with a chair or a pay phone?"
nize commonalities between animals and (feeding); "A squirrel or an alligator beplants more readily than those between ani- comes bigger, though it was small when it
mals and nonliving things but also suggest was a baby. Do you think anything similar
which properties children use as cues to rec- to this occurs with a tulip or a pine tree/with
ognize animal-plant commontdities.
a chair or a pay phone?" (growth in size).
Method
Half the children were given the feedSubjects.—The snbjects were 40 5-year- ing question first, and the other half, the
olds, equal numbers of boys and girls (mean growing-in-number question first. All of
age 5 years 8 months, range 5-6 to 6-3), re- them were asked the first item initially for
cruited from the same kindergarten as those plants, then for artifacts. Here, when chilin Experiments 1, 2, and 2A. They had not dren did not give any answer or answered
participated in any of the previous experi- no for this question for plants, they were
ments.
given a simple hint to help them understand
Procedure.—Each child was individu- what they were asked: for the feeding qnesally interviewed in a small room. After being tion, "Does it ever happen sometimes that a
asked to identify each drawing of those six tulip or a pine tree will die if something is
examples of animals, plants, and inanimate not given?" and for the growing-in-number
things to be described below, the child was question, "Does it ever happen sometimes
told that animals (a squirrel and an alligator) that a tulip or a pine tree will increase in
reveal such-and-such a phenomenon and number gradually by producing somewas then asked whether plants (a tulip and thing?" This hint was given only for the first
a pine tree) or artifacts (a chair and a public question for plants and never given for any
telephone) would reveal any similar one. of the subsequent questions, including the
When the child replied yes, he or she was feeding question or the growing-in-number
further asked what it was. Here we used two question for artifacts. Irrespective of
instances of artifacts, because asking young whether the child recognized the common
children to recognize a similar phenomenon phenomenon for plants after this simple
for an apparently mixed category of artifacts hint, the experimenter moved on to the same
and nonliving natural kinds seemed too de- question for artifacts, then all other questions. (In actuality, as described later, almost
manding.
all the subjects who needed the hint seemed
The target phenomena covered major to have understood what was subsequently
biological functions, that is, nutrition, excre- requested of them; they not only recognized
tion, respiration, growth and death, and re- a similarity bnt also offered a similar pheproduction. Specifically, they were (a) feed- nomenon.)
ing needed to maintain life, (fo) growing in
The order of the questions about the
number by having babies or laying eggs.
prehensible for most of them.^ Asking children about the commonalities between an
example of an animal and one of a plant often induced local comparisons which were
not applicable to these categories in general.
The only method that had proven to work
was asking children whether a few examples
of plants or those of nonliving things show
phenomena similar to those observed for a
few examples of animals.
^ Tbe Japanese word corresponding to "plant" is not an everyday household term. It is not
used with nearly as much frequency as the English word. Japanese people usually refer to less
inclusive categories, like fiowers, trees, or grasses. "Plant" is a word for scientific discourse.
Thus, in our pilot testing, nine out of 12 first graders answered tbat tbey bad never beard of tbe
word.
Inagaki and Hatano
2835
eight phenomena was randomized for each
subject except for the first item (i.e., feeding
or growing in number) and the last item of
being ill-fed. The "ill-fed" phenomenon
was given only for the series beginning with
the growing-in-number question as the first
item. Thus a child in this series was given
eight qnestions for plants and eight questions for inanimates in all. A child in the
other series was given seven questions each
for plants and inanimates. The questions for
plants and for inanimates were asked about
a phenomenon before the inquiry proceeded
to another phenomenon. Half the subjects in
each series were asked about plants first, and
the other half, artifacts first, except for the
first item.
nizing a similar phenomenon for artifacts but
not for plants). The difference was significant for all the phenomena except for excretion, ps < .01. The differential responding
for plants and artifacts was especially clear
for feeding and growth in size; for the former
85% (17/20) of the children showed yes-no
patterns and for the latter 90% (36/40) of
them did so. About 70% of the children indicated yes-no patterns for becoming older
and dying; about 50% of them did so for being ill-fed, growing in number, and breathing; and 30% of them showed this pattern
for overfeeding. Children did not appear to
respond mechanically by saying yes to
plants and no to artifacts, because a majority
of them responded no to plants for excretion.
Results and Discussion
We first describe the responses to the
initial items, that is, feeding or growing in
number with and withont a hint for plants,
and for artifacts without a hint. For feeding,
out of the 20 children 13 (65%) answered
without a hint and seven (35%) with a hint
that a similar phenomenon could be observed in plants as well, and all of them referred to watering in plants as a phenomenon similar to feeding in animals. For
growing in number, six children out of the
20 spontaneously recognized the existence
of the similar phenomenon in plants, and 10
more did so when given a hint. These findings indicate that the simple hint helped
children understand what the question required. All but four children for the feeding
and all but two for the growing in number
items denied the possibility that similar phenomena are observed in artifacts. All of the
affirmative answers for artifacts were metaphorical: for example, for feeding, "A pay
phone cannot be used if we don't put a coin
in it," and "If a person doesn't sit on the
chair, there is no need to have it," or for
growing in number, "If a chair is broken, a
person can make another one."
What phenomena in plants did the children give as similar to the target phenomenon for animals? For feeding, almost all children (94%) who gave yes responses for
plants answered, "A tulip or a pine tree
withers if we do not water it." For growing
in size, 12 of the 37 children who gave yes
responses for plants offered the phenomenon of a plant's getting bigger from a seed
or a bud. Another 14 children referred to watering as corresponding to feeding as a condition for growth, saying, "If we give water,
it will become bigger and bigger." One of
these children explicitly asserted, "(A tulip
or a pine tree) becomes bigger, because water is food for it."
Table 5 shows the percentages of yes
responses, that is, the children's recognition
that plants or artifacts revealed a phenomenon similar to that for animals. Here the responses to the first items (for both plants and
artifacts) are excluded. As is evident, the
children very often recognized similar phenomena for plants but almost never for artifacts. We tested the statistical significance of
the difference between the two percentages
by a binomial test, that is, by comparing the
frequency of yes-no patterns (recognizing a
similar phenomenon for plants bnt not for
artifacts) with that of no-yes pattems (recog-
For becoming older and dying, a great
majority (88%) of the 32 children who gave
yes responses for plants offered, withont
considering their becoming old, the phenomenon that plants wither or die, saying,
"If we do not give water, a tulip or a pine
tree will wither," or "A tulip or a pine tree
withers. That point is similar." Only a small
number referred to becoming older; one
child said, "Even if we give water to (a tulip
or pine tree), it will wither after living long."
A small number of affirmative responses
about the existence of similar phenomena
for artifacts were metaphorical, such as, "A
chair or a telephone is thrown away when it
no longer works."
For growth in number by reproduction,
six of the 10 children who recognized the
similarity between animals and plants referred to seeds. They stated that buds come
out from seeds buried in the ground and
grow in number (or produce many fiowers)
as a phenomenon similar to animals' increasing by having babies or laying eggs. Other
children seemed to regard plants having
Plants
Artifacts ...
Feeding
Growii
in Num
Growing
in Size
ming Older
id Dy ing
erfeeding
cret ing
Ill-Fed
o
Bretithing
m o
o
CO O
W
coco
O
O CO
QO t ^
M
CO CO
be ^
O IO
Inagaki and Hatano
flowers again and again or becoming thickly
covered by leaves as a similar phenomenon.
For being ill-fed, almost all the children
referred to the relation between watering
and growth, for example, "If we give it [a
tulip or pine tree] only a little water, it will
not become bigger," or "A small amount of
water will keep it [a tulip or pine tree]
small." For overfeeding, 10 of the 13 who
recognized similar phenomena for plants
pointed out the fact that too much watering
causes plants to wither or die. One of them
said, "If we give too much water, a tulip and
a pine tree will have a stomachache."
As partly inferable from the above description, almost all who answered that there
was a similar phenomenon for plants to any
of the eight questions were able to give a
concrete example. In other words, "no" answers or the "don't know" answers were
negligible in number. However, for breathing, half of the 18 who gave yes responses
could not specify the similar phenomena
and another three gave incomprehensible
answers.
In sum, children as young as 5 years of
age grasp explicitly the commonalities between animals and plants, and can thus differentiate both animals and plants from nonliving things. This conscious grasp of the
commonalities is at a functional level and
may often be achievedfirstwith feeding/watering and growth in size and then generalized to other biological phenomena.
General Discussion
2837
tics or processes similarly to animals and
plants but not to nonliving things (e.g., Backscheider et al., 1993; Hatano et al., 1993;
Springer & Keil, 1991). It is likely that young
children possess a higher-order category of
living things, though this tentative conclusion has to be tested with more varied exemplars.
More importantly, the present study offers three pieces of strong evidence for
young children's recognition of commonalities between animals and plants. First, for
5-year-old children, inductive projection
that was extended to plants was enhanced
by vitalistic explanations of the target properties for humans (Experiments 2 and 2A).
We interpret this result to imply that "biological" functions that had been assigned to
humans were applied to plants as well as to
other animals. In other words, humans, other
animals, and plants were regarded as entities that were covered by a single theory of
biology. Second, a considerable number of
the children showed an inductive projection
pattem constrained by the category of' living
things for plural properties (Experiments 2
and 2A). It is unlikely that they attributed a
given property to both animals and plants
independently but correctly. Third, a majority of the 5-year-olds could offer for plants
specific phenomena analogous to those observed for animals (Experiment 3). They
consciously recognized that animals and
plants are so similar that most phenomena
can be mapped from the former to the latter.
Thus, we conclude that children as
young as 5 years of age can categorize aniThe present research showed that 4- and mals and plants together, if their attention is
5-year-old children treated animals and directed to some salient characteristics that
plants alike as entities undergoing autono- animals and plants share. This means that
mous changes in size (and also in shape) young children are likely to have an autonoover time, but nonliving things as unchang- mous domain of biology, because it is genering (Experiment 1). A majority of the 5-year- ally agreed that plants are not included in
olds could spontaneously use the category the domain of psychology (Carey, 1995). The
of living things to constrain inductive projec- evidence is far from showing that they postion for properties of growth and taking food/ sess a highly developed, coherent, and comwater, and half of them did so for being plete theory of biology, but it does indicate
taken ill, when the properties were properly that they possess a biology separate from
phrased and brief vitalistic explanations psychology. Thus, Carey's (1985) earlier
were given (Experiments 2 and 2A). More- claim that children 7 years old or younger
over, when directly asked whether plants or have no form of biology and rely on psycholartifacts would show anything similar to ogy instead seems untenable.
those biological phenomena observed for
animals (including growth, taking food/waThe present stndy has also suggested,
ter, and becoming older and dying), they re- through the various methodologies, how the
sponded affirmatively for plants but not for recognition of the animal-plant commonalinonliving things (Experiment 3). These re- ties originates. Although the ontological dissults corroborate several recentflndingsthat tinction between living and nonliving things
young children attribute some characteris- is neither easy nor obvious (Gelman, 1996),
2838
Child Development
there are several properties which are relatively easily recognized as characteristics
common to animals and plants. Among others, growth and taking food/water seem the
core characteristics in the young children's
recognition of the animal-plant commonalities. Our children, like subjects in the previous studies reviewed at the beginning of this
article, recognized that both animals and
plants grow (Experiments 1, 2, and 3). The
case of taking food/water was a little more
complicated, because predicates like "eat"
or "take food" cannot be applied to plants.
However, our children seemed to know that
both animals and plants need sources for vital power and that feeding-for-animals and
watering-for-plants are analogous (Experiments 2A and 3).
We would like to emphasize that these
two and a few other related characteristics
form a coherent configuration. For example,
children often connect growth to taking
food/water, as illustrated by the results for
the "ill-fed" question of Experiment 3 ("A
small amount of watering makes plants grow
only a little"). It should be pointed out that
the children in Experiment 2 generalized
growth to plants much more readily when
they were given the context referring to food
and water as the source for vital power inducing growth. Being taken ill may also be
connected to the loss of vital power and thus,
like becoming older and dying, may be
linked to food and water; energy taken in
from food or water may prevent or inhibit
animals' or plants' death or ill health. In fact,
a substantial number of 6-year-old children
in Inagaki (1995) asserted that humans could
live for 100 or 200 years if they had enough
food and that energy or vital power taken in
from food prevented them from becoming
ill.
Let us speculate how these two properties or features (i.e., growth and taking food/
water) become the core in the recognition of
the living-nonliving distinction. Two possible interpretations can be proposed. The
first interpretation is that these features are
so perceptually salient that plants can
readily be grouped together with animals
based on the features. Growth, especially
unidirectional and/or long-term cyclic (seasonal) changes in plants, may be considered
as salient, though they are less attentiondrawing than the self-initiated movement of
which animals are capable. However, we believe that growth is not so obvious because it
takes time, and recognizing growth requires
being able to remember the past state of the
target object. Taking food/water is even less
conspicuous for some plants.
The second, and our preferred, interpretation is that these properties are attended to
in spite of the fact that they are nonobvions
features (Wellman & Gelman, 1992). This is
because, we assume, one of the domainspecific conceptual principles (Gelman,
1990) in biology indicates that living things
mean those beings which are similar to humans in terms of taking in vital force from
food and water, with its surplns inducing
growth. As soon as young children become
disposed to treat plants as living things, they
will find it quite feasible to apply this principle to plants; plants become active and
lively by taking in vital power from water,
and a surplus of vital power induces their
growth. This may partly be due to young
children's lack of understanding of photosynthesis.
The above domain-specific conceptual
principle stresses the individual survival
and growth aspect of life as the basis for children's grasp of the commonalities between
animals and plants. It also emphasizes that
aspect for the understanding of biology in
general. However, this does not mean that
we can ignore the reproduction aspect. Preserving the species or one's own genes is
probably the supreme goal of living entities.
Even young children have an intuition that
offspring resemble their parents (Solomon,
Johnson, Zaitchik, & Carey, 1996; Springer,
1992). However, whether they readily understand the biological nature of inheritance
is debatable (Hirschfeld, 1995; Solomon et
al., 1996; Springer, 1992; Springer & Keil,
1989). Because children do not engage in the
enterprise of reproduction whereas they do
in that of taking in food to grow, it is conceivable that they understand biologically relevant causal mechanisms more easily in the
latter. Thus, we posit that early biology is
established aronnd the enterprise of taking
in food and growing.
Further studies are needed to examine
how this early recognition of animal-plant
commonalities is acquired. An especially interesting issue is the role played by culture
in the acquisition. If the core properties
common to animals and plants are nonobvious, culture is likely to influence the acquisition of this recognition. Some previous studies (Hatano et al., 1993; Stavy & Wax, 1989)
have in fact shown that the status of plants in
children's biology varies considerably from
culture to culture. Observing in detail cul-
Inagaki and Hatano
2839
and cognitive development (pp. 117-150).
New York: Academic Press.
Gelman, S. A., & Kremer, K. E. (1991). Understanding natnral cause: Children's explanations of how objects and their properties originate. Child Development, 62, 396-414.
Hatano, G., Siegler, R. S., Richards, D. D., InaAppendix
gaki, K., Stavy, R., & Wax, N. (1993). The deFeeding: A squirrel or an alligator will die if
velopment of biological knowledge: A multiwe do not feed it. Do you think anything similar
national study. Cognitive Development, 8,
to this occurs with a tulip or a pine tree/with a
47-62.
chair or a pay phone? (The part italicized was
Hirschfeld, L. A. (1995). Do children have a therepeated for all the questions described below.)
ory of race? Cognition, 54, 209-252.
Overfeeding: A squirrel or an alligator be- Inagaki, K. (1995, October). Youjino shintaigensycomes ill when it eats too much food.
oni taisuru seikirontekisestumei [Young chilGrowing in size: A squirrel or an alligator
dren's explanations for bodily processes in
becomes bigger, though it is small when it is a
terms of vital power]. Paper presented at the
baby.
59th annual meeting of the Japanese Psychology Association, Okinawa, Japan.
Growing in number: A squirrel or an alligator
gradually increases in number by having babies Inagaki, K., & Hatano, G. (1987). Young children's
or laying eggs.
spontaneous personification as analogy. Child
Development, 58, 1013-1020.
Excreting: A squirrel or an alligator gets rid
of waste matter outside the body as feces or urine. Inagaki, K., & Hatano, G. (1993a, March). Developmental changes in biological attributions
Becoming older and dying: A squirrel or an
by young children: A longitudinal study. Paalligator becomes older little by little and dies at
per presented at the 60th meeting of the Socilast.
ety fof Research in Child Development, New
Breathing: A squirrel or an alligator takes in
Orleans.
fresh air by breathing.
Inagaki, K., & Hatano, G. (1993b). Young chilBeing ill-fed: A squirrel or an alligator does
dren's understanding of the mind-body disnot readily become bigger when it is fed only a
tinction. Child Development, 64, 1534-1549.
little.
Keil, F. C. (1983). On the emergence of semantic
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