The relevant domains in which to look for evidence include any that
are in principle rule-governed. Thus, chess and football are good
examples of systems; faces and conversations are not. Systemising
involves monitoring three things in order: input–operation–output.
The operation is what you did to the input, or what happened to the
input, to produce the output.
Toy preferences
Boys are more interested than girls in toy vehicles, weapons,
building blocks and mechanical toys, all of which are open to being
'systemised'
[22].
Adult occupational choices
Some occupations are almost entirely male. These include
metalworking, weapon making, manufacturing of musical instruments,
or the construction industries, such as boat building. The focus of
these occupations is on constructing systems
[23].
Maths, physics, and engineering
These all require high systemising, and are largely
male-dominated disciplines. The Scholastic Aptitude Math Test
(SAT-M) is the maths part of the test administered nationally to
college applicants in the USA. Males on average score 50 points
higher than females on this test
[24]. Taking
only those people scoring above 700, the sex ratio is 13:1 (men to
women)
[25].
Constructional abilities
If you ask people to put together a 3-D mechanical apparatus in
an assembly task, on average men score higher. Boys are also better
at constructing block buildings from 2-D blueprints. Lego bricks can
be combined and recombined into an infinite number of systems. Boys
show more interest in playing with Lego. Boys as young as 3 yrs are
also faster at copying 3-D models of outsized Lego pieces, and older
boys, from the age of 9, are better at imagining what a 3-D object
will look like if it is laid out flat. They are also better at
constructing a 3-D structure from just an aerial and frontal view in
a picture
[26].
The Water-Level task
Originally devised by Swiss child psychologist Jean Piaget, this
task is to show someone an empty bottle, tipped at an angle, and
then ask them to show the water level when it is, say, half full.
Women more often draw the water level aligned with the tilt of the
bottle, and not horizontal, as it should be
[27].
The Rod and Frame test
If a person's judgement of vertical is influenced by the tilt of
the frame, they are said to be 'field dependent': their judgement is
easily swayed by extraneous input in the surrounding context. If
they are not influenced by the tilt of the frame, they are said to
be 'field independent'. Most studies show that females are more
field dependent – that is, women are relatively more distracted by
contextual cues, rather than considering each variable within the
system separately. They are more likely than men to say
(erroneously) that the rod is upright if it is aligned with its
frame
[28].
Good attention to relevant detail
This is a general feature of systemizing. It is not the only
factor, but it is a necessary part of it. Attention to relevant
detail is superior in males. A measure of this is the Embedded
Figures Task: on average, males are quicker and more accurate in
locating the target embedded within the larger, complex pattern
[29]. Males, on average, are also better at
detecting a particular feature (static or moving)
[30].
The Mental Rotation test
Here again, males are quicker and more accurate. This test
involves systemising because you have to treat each feature in a
display as a variable that can be transformed (e.g. rotated) and
predict how it will appear (the 'output')
[31].
Map reading
Reading maps is another everyday test of systemising, because it
is necessary to take features from 3-D input and predict how they
will appear when represented in 2-D. Boys perform at a higher level
than girls. Men can also learn a route in fewer trials, just from
looking at a map, correctly recalling more details about direction
and distance. This suggests they are treating features in the map as
variables that can be transformed into 3-D. If you ask school
children to make a map of an area that they have visited only once,
boys' maps have a more accurate layout of the features in the
environment than girls' maps. More of the girls' maps make serious
errors in the location of important landmarks. The boys tend to
emphasise routes or roads, whereas the girls tend to emphasise
specific landmarks (the corner shop, etc.). These two strategies –
using directional cues versus landmark cues – have been widely
studied (for example,
[32]). The directional
strategy is an instance of taking understanding space as a geometric
system and the focus on roads or routes is an instance of
considering space in terms of another system, in this case a
transport system.
Motoric systems
If you ask people to throw or catch moving objects (target
directed tasks) such as playing darts or intercepting balls flung
from a launcher, males tend to be better. Equally, if you ask men to
judge which of two moving objects is travelling faster, men are on
average more accurate
[33].
Organisable systems
People in the Aguaruna tribe (northern Peru) were asked to
classify a hundred or more examples of local specimens together into
related species
[34]. Men's classification
systems had more sub-categories (i.e. they introduced greater
differentiation) and more consistency between each other than those
of the women. The criteria that the Aguaruna men used to decide
which animals belonged together more closely resembled the taxonomic
criteria used by western (mostly male) biologists
[34]. Classification and organisation involves systemising
because categories are predictive. The more fine-grained the
categories, the better the system of prediction will be.
The Systemising Quotient
This questionnaire has been tested among adults in the general
population. It has 40 items asking about the subject's level of
interest in a range of different systems that exist in the
environment (including technical, abstract, and natural systems).
Males score higher than females on this measure (S. Baron-Cohen and
J. Reichler, unpublished data).
Mechanics
The Physical Prediction Questionnaire (PPQ) is based on an
established method for selecting applicants for engineering. The
task involves predicting which direction levers will move when an
internal mechanism (of cog wheels and pulleys) of one type or
another is involved. Men score significantly higher on this test
than women (J. Lawson
et al., unpublished data).
