i6oi 



IIWIIBOOK OF PHYSIOLOGY 



NELROI'HYSIOLOGY III 



morphic way of describing the receptor processes 

 which antedate perception 



Although the 'unconscious inference' theory of 

 von rlelmholtz has been revived in some of the cur- 

 rent studies of perception from the 'tr ansae tionalist' 

 viewpoint [see Ames (7), Ittelson & Cantril (236)], 

 the prevailing approach to the 'constancies' and to 

 the 'illusions' is based on the belief that nearly all 

 perception is perception of objects, and that the con- 

 stancies pervade perception on all levels, from the 

 most elementary to the most complex. 



Impact "i (,< stalt Psychology and 

 Operational />'< haviorism 



This unitary approach to perception can be credited 

 largelv to two sources: first, to Gestalt psychology 

 (and phenomenology) and second, to certain trends in 

 operational behaviorism. The Gestalt psychologists, 

 notably Wertheimer (536), Kohlcr (269) and KotTka 

 (284), from the outset rejected all notions of elemen- 

 tary sensory processes. To hear a pure tone or to see 

 a single contour meant to them to perceive organized 

 structures, and they considered it their task to search 

 for the laws underlying all perceptual organization. 

 In this respect, the) continued the tradition of phenom- 

 enology the careful description of sensory experi- 

 ence. In such descriptions, errors of perception were 

 not features to be eliminated; they were to be studied 

 as clues to the basis of normal function. Thus, Pur- 

 kinje (393) was convinced that "illusions of the senses 

 tell us the truth about perception" ("dass Sinnes- 

 tauschungen Gesichtswahrheiten sincl "); and he re- 

 corded the manifold phenomena of entoptic imagery — 

 the illusions produced by inadequate stimulation of 

 tin- retina, tiering (2011, 202), the main antagonist of 

 von rlelmholtz, surveyed phenomena of simultane- 

 ous and successive contrast, of afterimages and mem- 

 ory colors, demonstrating that a patient study of 

 sensor) phenomena leads to the discovery of many 

 problems for sensors physiology which a more rigid 

 psvchophvsical approach would unavoidablv pass 

 by. 



It is clear lh.it such phenomenal distinctions are 

 I1.1 id on consensual validation, an appeal to intro- 

 spections of the other man. In modern behaviorism 

 appeal- ol this son ,uc proscribed; die tendency has 

 been to reduce all studies of perception to that of 

 sensory discrimination, As Boring ( ~, () has pointed 

 out, this tendency, too, results m ,, denial oi any 

 dichotomy between sensation and perception; in 

 behav torism, sensation (in the form of discrimination) 



has absorbed perception, while in phcnomcnologv and 

 Gestalt psychology, perception has absorbed sensa- 

 tion. 



The Need for Converging Operations 



The reduction of perception to discrimination has 

 not gone without contradiction within the framework 

 of modern behaviorism itself. Thus, Garner et al. 

 (144) have pointed out that to reduce perceptions to 

 the overt discriminatory responses by which they are 

 observed would seriously restrict the scope of experi- 

 mentation. The reduction of perception to discrimina- 

 tion is usually defended by operational bchaviorists, 

 such as Graham (166), by referring to Bridgman's 

 critique of concepts in physics. For Bridgman (61), 

 "a concept is synonymous with the corresponding 

 set of operations," i.e. the experimental operations 

 by which the concept is established. However, this 

 does not mean that any operation will generate a 

 meaningful concept. If one thinks of perception as 

 intervening between stimulus and response, and thus 

 distinct from either of these two terms, it is obvious 

 that a particular kind of operation is needed to estab- 

 lish whether a series of events is perceptual in nature. 

 This can be done, as Garner el al. (1441 suggest, by 

 means of converging operations. These are any sets 

 of two or more independent experimental procedures 

 which lead to the same terminus, i e, establish .1 con- 

 cept by ruling out alternative interpretations. 



To take an example from a currently popular area 

 of experimentation consider the supposed difference 

 in perception of words, or of drawings, or symbols with 

 different emotional content [e.g. Met Jinnies (342 I . 

 In a hypothetical experiment of this type, lour words 

 are exposed at high speeds (i.e. tachistOSCOpically) 

 and the subject is required to recognize them. If two 

 of these words are neutral, and two vulgar, the result 

 will be that the neutral words are read .11 high speeds, 

 while the vulgar words are not, or at least not until 

 their exposure has been made quite long. Such a 

 result is eouunonlv interpreted .is perceptual defense, 

 since failure to read is considered identical with 

 failure to perceive However, the failure to report 

 vulgar words may be .1 characteristic of the subject's 

 responses rather than his perceptions. A converging 

 operation would be 10 pair vulgar responses wilh the 

 neutral stimulus words, and vice versa l 144). Only 

 under these conditions could one decide whether the 

 'defense' was, in fact, perceptual, ll should lie noted 

 ih. 11 both operations are needed il one cares to estab- 



