2IO SECTIONAL ADDRESSES 



effects is born with us, but that individual differences in the amount of 

 phenomenal regression are largely or wholly determined later by individual 

 experience. If phenomenal regression is to be regarded as a product of 

 the organisation of individual phenomenal space, there may be other 

 aspects of spatial organisation whose changes run parallel to the changes 

 in phenomenal regression. It would, for example, be interesting to know 

 whether there is a parallel change in size contrast effects with increasing 

 years. 



V. Practical Consequences. 



It may be asked whether the kind of thing we have been talking about 

 has any practical importance. It certainly may have. We test for such 

 differences in the sensory physiology of the eye as colour-blindness 

 because they may lead to practically important incapacities, and it is very 

 likely that individual differences in the cerebral side of perception may also 

 affect an individual's practical capacities. Some years ago I suggested 

 that a person of high phenomenal regression might be expected to drive 

 a car more easily through traffic than one with low. He sees a gap in the 

 traffic in something near its real size before he drives up to it, whereas 

 the person with low phenomenal regression sees it as smaller than it 

 really is when it is at a distance. Neither, of course, adjusts his driving 

 to the apparent size of the gap ; both must make a judgment as to its real 

 size. The person with low phenomenal regression has, however, a much 

 larger gulf between appearance and reality to bridge by means of judg- 

 ment. Judgment being a slower and more uncertain process than per- 

 ception, he may be expected to drive through gaps with more difficulty 

 and less certainty than the individual who can trust to his immediate 

 impression of size. The individual with high phenomenal regression may 

 therefore be expected to drive more easily and better through traffic. 

 This prediction appears to have been justified by a research in motor 

 driving by the National Institute of Industrial Psychology, who found 

 that a test of phenomenal regression showed a correlation with driving 

 ability. 



It has already been mentioned that some individuals show the odd 

 peculiarity of seeing objects as larger when they go farther from the 

 eyes. This may be called * anomalous phenomenal regression ' or 

 ' superconstancy.' It seems to be rare. I have found two cases in the 

 course of testing over two hundred subjects. These showed the peculiarity 

 (each over a certain range of distances) repeatedly and under different 

 conditions of testing, so there is no doubt of its reality. One subject who 

 was presbyopic was tested with and without "glasses and gave identical 

 results, so it is not due to any peripheral defect of vision. Theoretically 

 this condition is interesting. It seems strongly to indicate that the ex- 

 planation of phenomenal regression is not to be found wholly in experience, 

 since it is inconceivable that any experience should have taught the 

 subject that, of two objects casting equal retinal images, the nearer is the 

 larger. I can suggest no explanation. All that we can say at present 

 is that the organisation of these individuals' phenomenal space is such that 

 there is a reversal at some distances of the ordinary condition that an object 



