Intuitive Physics: Across Tasks and Age
Cedar Riener, Dennis Proffitt, Timothy Salthouse
Department of Psychology
University of Virginia
The second approach has sought to analyze the specific problem or task and explain errors based on characteristics
of each task. McAfee and Proffitt (1991) explained errors on the water level task by applying a universal perceptual
bias. These authors pointed out that the water-level task is not necessarily a problem which tests one’s knowledge of
whether water remains horizontal regardless of the orientation of the container. Performance on the water level task
could reflect how one represents the problem; either based on an environment-centered coordinate frame or a containercentered coordinate frame. Representing the problem with a container-centered frame of reference induces a well-known
perceptual bias; misperceiving the horizontal in the same direction of the container. While this explanation explains the
errors in the water level task, it does not apply well to other tasks, such as the c-shaped tube problem. Proffit and Gilden
(1989) explained errors in natural dynamics tasks as related to the complexity of the problem, not the principles tested.
This approach is broad in its scope (it applies to many physical events) but it is limited in its precision, in that it makes a
binary distinction between simple and complex problems.
Our research is aimed at answering questions at a more fundamental level. If there are compelling explanations for
individual physics tasks, but no generalized theory, do we still have reasons to believe that intuitive physics tasks belong
to a single category? If we hope to choose between the accounts discussed above, it would be useful to know whether
there were reliable individual differences in performance across the range of intuitive physics tasks. In search of
evidence for or against the unity of intuitive physics task, our research addresses the question: Does intuitive physics
performance reflect an underlying disposition? We also sought to elaborate on the nature of this hypothesized
disposition by further investigation. We examined how this disposition relates to general mechanical reasoning ability.
We used subjects from across the adult lifespan to test the persistence of intuitive physics ability. Finally, we compared
our measure of intuitive physics ability to other well-known measures of cognitive ability to better understand the nature
of this disposition. These results yield insights which are valuable not only to the study of intuitive physics, but also to
the study of cognitive aging.
 Intuitive Physics Items:
 5 pairs of standard intuitive physics tasks (see below)
 204 participants
 Ages 20-91
 Broad cross section of healthy adults
only 7% in school
 Mean years of education = 16
 Standardized battery of Mechanical Reasoning Items:
 6 items from the Woodcock Johnson Mechanical Reasoning subtest
 Standardized Battery of Fluid Intelligence Items:
 Average of the z-scores from the Woodcock Johnson Analysis-Synthesis and
Wechsler Block Design
1. Intuitive physics performance does reflect a unitary disposition.
 The intuitive physics items are strongly correlated with
the mechanical reasoning items, suggesting that they
reflect the same underlying ability.
 Cronbach’s coefficient α
= 0.74
Nunnally (1978) sets criteria at 0.70
 Standardized Battery of Crystallized Intelligence Items:
 Average of the z-scores from the Wechsler Vocabulary subtest and the Woodcock
Johnson Picture Vocabulary subtest
Intuitive Physics Items
Pendulum Problem
The pendulum below is swinging from side to
side. The string is cut when the pendulum
reaches its highest point (indicated by the
scissors). Draw the path of the pendulum bob
as it falls to the ground.
Water Level Problem
The c-shaped tube you see below is lying flat on
a table (this is an aerial view). A ball is placed
in one end and launched so that it proceeds
through the tube and out the other side. Draw
the path that the ball will take once it exits the
tube, starting at the given point.
On the left is a glass of water sitting on the
table. On the right, the glass has been tilted.
Assume that the glass and water are now
stationery. Draw the line showing the top
surface of the water, given that it ends at the
indicated point.
 Even if factors do exist, they are weak.
 5 factors with eigenvalues greater than 1.
 Only the first factor accounts for more than 6% of
variance (19.1%)
 all five together only account for 36.2% of
variance
2. This disposition is persistent
3. Intuitive physics performance is
across the adult lifespan.
strongly correlated with fluid
intelligence.
16
C- Shaped Tube Problem
b. Factor analysis
a. Tests of Reliability
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80
Fluid Intelligence
Chronological Age
The Paradox of Intuitive Physics and Aging
Archimedes Principle Problem
The picture on the left shows a styrofoam disc floating in a tub of
water. A clay ball is attached to the top of the disc with glue. The
water level on the tub is marked with an “X.”
Fluid Intelligence
There are two sources of evidence against a theoretical explanation of intuitive physics performance. First of all, the
surface characteristics of the problem can affect performance. For example, while many participants erroneously report
that a ball exiting a c-shaped tube will continue to curve, very few also believe that water exiting a curved hose will also
continue to curve (Kaiser, Jonides & Alexander, 1986). Secondly, while impetus beliefs may explain performance on
the c-shaped tube task, they do not generalize well to other intuitive physics tasks. The beliefs that have been invoked to
explain performance on intuitive physics tasks, while making precise claims and predictions, lack the scope that would
allow them to explain performance across the range of intuitive physics tasks.
Assessments
Sample
Intuitive Physics Performance
A number of tasks have been adopted to test people’s intuitive understanding of physics. These tasks have met with
surprising results. Instead of demonstrating comprehension of basic physics, many studies in the field of intuitive
physics have shown that a large percentage of adults display a systematic misunderstanding about the simple principles
which govern physical events (Champagne, Klopfer, & Anderson, 1980; Caramazza, McCloskey, & Green, 1981).
Much of the previous work in the field of intuitive physics has focused on two major approaches to explain these
unexpected results. The first approach asserts that the systematic errors observed on intuitive physics tasks are due to
systematically incorrect implicit theories of physics (McCloskey, 1983). Jean Piaget showed that young children were
not simply failing at certain tasks, but instead showing systematic biases (Piaget & Inhelder, 1956). This led him to
propose that children went through stages of theoretical development which reflected a non-incremental reorganization
of knowledge. McCloskey observed that when adult participants were given the c-shaped tube task (see Intuitive
Physics Items on right) they behaved as if they possessed something akin to medieval impetus theory (McCloskey &
Kohl, 1983). Those participants that drew a curved path for a ball exiting a c-shaped tube seemed to hold a belief that
the curvilinear “impetus” imparted to the ball by the tube gradually dissipates after the ball exits the tube.
Results
Methods
Intuitive Physics Performance
Introduction
Falling Object Problem
This airplane is carrying a canister of supplies as it flies
over a field. The plane drops the canister. Draw the path
that the canister will follow before it hits the ground.
The disc and the ball are then removed from the tub and placed back
into the tub, upside down (as shown). Where will the water level be
relative to the case on the left? (above, the same, or below the X)
(circle one)
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Given that fluid intelligence
decreases with age, and intuitive
physics performance is highly
correlated with fluid intelligence,
one would expect that intuitive
physics performance would also
decrease with age. It does not.
80
Chronological Age
Conclusion
X
?
The performance of participants in our study offers compelling evidence that intuitive physics performance is indeed
reflective of a general mechanical reasoning ability. Furthermore, this ability is stable across the adult lifespan, as well as
highly correlated with measures of fluid cognitive ability.
Research Questions
1. Does intuitive physics performance reflect a
unitary mechanical reasoning disposition?
2. Is this disposition persistent across the adult
lifespan?
3. How is intuitive physics related to other
cognitive abilities?
In asserting that intuitive physics performance is influenced by a mechanical reasoning ability, we seek to
complement, rather than disprove, current theory approaches or individual problem explanations. The fact that individuals do
differ in their ability to solve these intuitive physics problems does not preclude other reasons to explain errors on certain tasks.
Future researchers can design intuitive physics studies knowing that a certain amount of the variance that they see in their
performance data can be attributed to individual differences in a mechanical reasoning ability. By assessing this ability prior to
administering the intuitive physics problems, this variance could be controlled for, allowing other patterns in the data to be
more easily recognizable.
Mechanical Reasoning Items
The Mechanical Reasoning Items are made up of 6 multiple choice items which require mechanical reasoning using
physical concepts such as center of mass, gravity, and collision dynamics.
Applying our findings to the two major approaches discussed in the introduction, the evidence for an underlying
mechanical reasoning ability seems to lend support to the account discussed by Proffitt and Gilden (1989). Our evidence
suggests an expansion on this account. Rather than splitting intuitive physics tasks between easy and hard categories along the
lines of problem complexity, perhaps items can be placed on a continuum of difficulty. Just as certain people are more likely to
get more intuitive physics problems wrong, there are certain problems which are harder than others.
Finally, the paradox of intuitive physics and aging is important to the aging community. Despite its high level of
correlation with fluid intelligence, intuitive physics ability seems to remain stable across the lifespan. This stability could
indicate that rather than being considered a form of fluid intelligence, general mechanical reasoning ability is better conceived
as a form of concrete knowledge, or crystallized intelligence.
Fluid and Crystallized Intelligence Tests
References
Fluid intelligence was measured by taking an average of the z-scores from the Woodcock Johnson Analysis-Synthesis
and Wechsler Block Design subtests. These subtests provide an approximate measure of one’s facility with processing
given information, regardless of experience or stored knowledge.
Crystallized intelligence was measured by taking an average of the z-scores from the Woodcock Average of the zscores from the Wechsler Vocabulary subtest and the Woodcock Johnson Picture Vocabulary subtest. These subtests
provide an approximate measure of the level of stored knowledge that an individual has acquired by testing vocabulary
and picture recognition.
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* This research was supported by funds from the Virginia Aging Initiative directed by Timothy Salthouse
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Caramazza, A., McCloskey, M., & Green, B. (1981). Naive beliefs in "sophisticated" subjects: Misconceptions about trajectories of objects. Cognition, 9(2), 117123.
McCloskey, M. (1983) Intuitive physics. Scientific American. 248(4), 122-130.
Piaget, J., & Inhelder, B. (1956). The child’s conception of space. London: Routledge and Kegan Paul.
McCloskey, M., & Kohl, D. (1983). Naive physics: The curvilinear impetus principle and its role in interactions with moving objects. Journal of Experimental
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