_I_ (50) - 32.76 41.60 24.40
_K_ (50) - 61.70 100.02 52.44
_L_ (40) -128.70 128.90 27.83

Average: - 36.62 67.16 31.43


Changes in two directions may be looked for in the results as the
experimental conditions are thus varied. The first is a decrease in
the certainty of judgment due to the simple elimination of certain
factors upon which the judgment depends. The second is the appearance
of definite types of error due to the withdrawal of certain
correctives of organic tendencies which distort the judgment in
specific directions. The loss in accuracy is great; the mean variation
increases from 7.69 to 31.43, or more than 400 per cent. This large
increase must not, however, be understood as indicating a simple
reduction in the observer's capacity to locate points in the
horizontal plane of the eyes. The two series are not directly
comparable; for in the case of the lighted room, since the whole
visual background remained unchanged, each determination must be
conceived to influence the succeeding judgment, which becomes really a
correction of the preceding. To make the two series strictly parallel
the scenery should have been completely changed after each act of
judgment. Nevertheless, a very large increase of uncertainty may
fairly be granted in passing from a field of visual objects to a
single illuminated point in an otherwise dark field. It is probable
that this change is largely due to the elimination of those elements
of sensation depending upon the relation of the sagittal axis to the
plane against which the object is viewed.