The Mind of the Buyer

S T REAM O F T H OUG H T IN SA L E (^13)
resul ts, be it understood, in m a th ema tical
terms. Acc ordingly a. very imp or ta n t p a rt
o f our rec o rd s will b e fi gure s.
3. Our n ex t step is to ta bula te th ese fig
ure s i n orde rly a rray, th e n to summ a ri z e th em
i n a c oncise fo rm so th a t th ey may b e rea dily
p erceived.
(^4). O n th e basi s o f th e result s sec ure d we
d raw c o nclusio ns.
In orde r to ill ustrat e thi s p ro c edure w e
sh all give an exp erimen t which i s som etime s
pe rfo rm ed i n th e psych ol ogi cal lab ora to ry :
A PS Y CH OLOGICA L E! PER IM EN T
( A dapted from C. H. Judd, “ Laboratory M anual o f
Psychology” by kind permission o f Ginn Co. )
Hold page^15 dire ctly in front o f the eyes at a distance
o f about twenty inches. Though these two lines are equal
length ( 1 0 centimeters : 4 inches) , the horizontal line ap
pears to be sho rter than the vertical o ne. There is a
psychologi cal fact at the bottom o f this : namely, that the
a pp a rent length o f a line depends to some degree upon its
position. This much is evident from casual obse rvation.
B ut to have a scientific statement o f the fact we must state
how much e ffec t is produced by cha nging the line from
the horizontal to the vertical position. We must measure
the e ffect and state it in mathematical terms.
In orde r to do this, cove r the vertical line with a p iece
o f plain p aper, setting the page up in front o f the eyes at
a distance o f twenty inches. Then, using the ho rizontal
line as a standard, draw o n a p iece o f plain paper, a vertical