324 REPORTS ON THE STATE OF SCIENCE, ETC. 



This is the case in the majority of experiments of the kind we are considering 

 in which artificial groupings of a few bright objects isolated against a dark 

 background, or a few isolated sounds produced in unfamiliar ways, are 

 perceived. There is nothing in such systems to evoke the correlative 

 associations involved in phenomenal regression, and judgment will depend 

 almost entirely on the immediate sensory reaction. The psychological 

 relation structure due to the direct effect of the stimuli on the sense organ, 

 if for any reason it does not happen to be the norm associated with the 

 particular phenomenal relation exhibited, will not be ' corrected ' towards 

 this norm : we shall simply judge, wrongly, that we perceive the phenomenal 

 relation for which the impression we receive is the associated norm. Con- 

 sequently if all the relevant properties of the sensory system are not constant 

 throughout the range of intensity covered by the series of stimuU we shall 

 not judge the stimulus relations correctly. Our criterion will still, however, 

 be the perception of sameness of relation shape in the phenomenal relation 

 structures consisting of adjacent pairs of stimuH, but our judgment when 

 this is achieved will be in error. 



The extent, therefore, to which any experiments of this kind fail to grade 

 stimuli in a geometrical progression is simply an indication of the extent to 

 which the sense organ under investigation fails to tell us the truth. The 

 particular causes of this failure in any particular circumstances are the 

 business of the physiologist and possibly, also, the psychologist ; but 

 neither compliance with the law of geometrical progression, nor the 

 departures from it which may be observed, can lead to the discovery of any 

 quantitative relation between sensation intensities and stimulus intensities. 



The ' apparent ' phenomenal structure will always be that for which the 

 immediate psychological structure of any instance of perception has been 

 related as a norm by the associative bond of integrated experience. In 

 particular, any two phenomenal structures will be ' perceived ' to have the 

 unique relation of sameness, whether they really have or not, if in a given 

 act of perception the psychological relation structures which they evoke 

 are related to each other by the psychological relation which is the norm 

 associated with sameness of objective relation structure. Thus, any 

 difference which may ever be manifested between the ' apparent ' relations 

 of phenomena and the ' true ' relations, do not involve any law of variation 

 of sensation intensity with stimulus intensities, but only arise from the fact 

 that from some cause, either adventitious or systematic, the phenomenal 

 relation structure under observation is not producing the normal psycho- 

 logical relation structure which is associated with these phenomenal relations 

 by the totality of our experience. The reason for it not doing so in any 

 particular case may be physiological or psychological or both. We cannot 

 expect any physiological mechanisms, such as those involved in our receptor 

 organs and neural systems, to exhibit constant properties at all intensities 

 of stimulation. We do know, however, as an empirical fact, that over the 

 range of conditions typical of the bulk of our ordinary experience, our 

 individual perceptions give us a fairly faithful account of phenomenal 

 relations ; so within this range the differences between apparent and true 

 phenomenal relations cannot be great. We should, however, expect to 

 find more important departures at intensities lower or higher than those for 

 which the bulk of our associative experiences are obtained. We should 

 therefore expect in mean-gradation experiments to find stimuli to be graded 

 by perception in the ratio of their intensities, or nearly so, within the range 

 of ordinary comfortable perception, but to exhibit departures from this 

 relation at high and low intensities. 



This is, in general, what is found when the experiments are carried out. 



