;54 



NATURE 



[January 3, 19 18 



many of its expressions is extremely complex. The 

 author has no use for psychological assumptions, such 

 as that the rat "perceives relations," or "makes prac- 

 tical judgments," or "has ideas." We do not know 

 why "it is needless to say that no evidence of idea- 

 tional behaviour has been found in the white rat." 



When a rat emerges from a blind alley in the maze, 

 it may run forward or it may return on its own track. 

 But with experience the percentage of returns rapidly 

 decreases, especially in the case of the culs-de-sac nearer 

 the end of the journey — the food-box. There is a pro- 

 gressive elimination of entrances to blind alleys, but 

 this does not come about mainly by a decrease in the 

 number of entrances, but principally, especially in the 

 case of the longer alleys, by a gradual decrease in the 

 degree or distance of entrance. " Just before entrance 

 is eliminated completely, there frequently occurs a 

 peculiar and very rapid vibration of the rat's head be- 

 tween the direction of the true path and that of the 

 tempting blind alley." Entrances to short culs-de-sac 

 are eliminated more readily, other things being equal, 

 than entrances to long ones. 



Many facts indicate that to a large extent the maze 

 is learned "as a whole." There must be "some sort 

 of short-circuiting process " by which the right path 

 is suggested for the line of action when the animal 

 comes to the entrance of any blind alley. " It is not 

 clear how any of the usually accepted laws of learning 

 — frequency, recency, and intensity — can operate to 

 bring this about. Frequency and recency fail en- 

 tirely to account for the behaviour of the rat in the 

 maze. The real process of learning, the gradual 

 elimination of unsuccessful random acts, such as 

 entrances to culs-de-sac and returns towards the en- 

 trance place in the maze, must be accounted for on 

 the basis of some entirely different principle. The 

 principles named show only how an act, directed by 

 some other factor, becomes gradually more mechanic- 

 ally reflex." 



What, then, is the author's theory? He calls it the 

 " completeness of response " principle in learning. 

 " Responses to stimuli cannot take place instan- 

 taneously, neither do stimulation effects fade away 

 momentarily. Besides this, response tendencies and 

 muscular strains, maintained for a shorter or longer 

 time, constantly set up new sensorv impulses (proprio- 

 ceptive stimuli), which again stimulate reactions." By 

 such means the effects of successive stimuli, such as 

 the rat encounters in the maze, come to operate in a 

 measure simultaneously, and the resulting response is 

 on the whole the most consistent or complete that can 

 be given in the whole circumstance. " The channels to 

 this most complete response are gradually forced most 

 open or permeable ; their greater consistency of opera- 

 tion (facilitation) brings about an intensity of activity 

 through them, which in repeated trials gradually short- 

 circuits through the infinitely numerous pathways in- 

 volved, and thus brings about the gradual elimination 

 of useless random acts." This is not exactly luminous; 

 the author's theory is only tentative. 



It is suggested that learning comes about by this 

 means, and that theories of the " stamping-in of the 

 effects of pleasantness " or of the direction of the 

 animal by conscious states must be laid on the shelf. 

 It can scarcely be said, however, that Mr. Peterson's 

 new theory has yet reached a high degree of lucidity, 

 and there seems to us a smack of dogmatism in the 

 brushing aside of unfashionable ideational interpreta- 

 tions. But the conception of the overlapping of effects 

 of successive nerve functionings is very interesting, 

 and we shall look forward to hearing more of it — 

 especiallv as a suggested interpretation of the results of 

 ingeniously contrived and punctiliously controlled ex- 

 periments. 



NO. 2514, VOL. 106] 



' INTERNATIONAL FISHERY STATISTICS.^ 

 'I'HE publication of the eighth Annual Statistical 



■■■ Bulletin of the International Council for Fishery 

 Investigations is of interest from the point of view of 

 questions of post-war reconstruction. When the coun- 

 cil began its work in 1902 it was decided that an 

 annual summary of the commercial fishery statistics 

 of the maritime countries of northern Europe should 

 be compiled. Probably no one except those actually 

 engaged in this task of compilation has ever really 

 appreciated the difficulties of this work. There is no 

 uniformity in the methods of collection of fishery statis- 

 tics in the countries participating in the schemes of 

 investigation; the ideals of detail and accuracy have 

 always been very different, and official custom and 

 tradition have made it exceedingly difficult to modify 

 or change the methods. To all this we must add inter- 

 national susceptibilities; thus some of the official re- 

 ports of the International Council are framed in diplo- 

 matic style and published in French, but the Bulletin 

 Statistique is presented to the public in a queer mixture 

 of. English and German. Much of the matter, explana- 

 tions, discussions, headings, descriptions of tables, and 

 so on, are given in duplicate — an irritating and waste- 

 ful compromise. 



There has always been (an evidently inevitable) delay 

 in publication; thus the first bulletin, which appeared 

 in 1906, dealt with the statistics of 1903-4, while this 

 last one, published in 1917, summarises the data for 

 1911-12. The figures for the various fisheries are ad- 

 mittedly estimates and are rounded off, and there are, 

 apparently, no means of arriving at any notions of the 

 magnitudes of the errors involved. The whole treat- 

 ment is very general and detail is minimal. Now, with 

 all these defects the bulletins have achieved very much, 

 how much anyone may attempt to estimate by trying 

 to think of any other international industry for which 

 we have even an approximation to the knowledge 

 which we possess with regard to European fisheries. 

 The defects- of the bulletins are necessarily those of the 

 national systems of fishery statistics, which are the 

 sources of information. In May of 1914 the council 

 began to consider changes, both with regard to arrange- 

 ment and matter, and the possibilities of speedier pub- 

 lication. Then followed the events of the last three 

 years, postponing indefinitely this task of reconstruction. 



Ap'art from the improvement of the national statis- 

 tical systems, any improvement of the International 

 Bulletin would have been of little significance. Now 

 the hiatus in fishery investigation that has existed since 

 August of 1914 simplifies the task of reconstruction; 

 there has been a break of continuity which really in- 

 vites "scrapping" on a large scale. Nowadays there 

 is so much uniformity in general methods of fishing 

 and in commercial methods of distribution that there 

 is scarcely any excuse for diversity of treatment with . 

 regard to statistics ; given the will to improve and 

 there need be no reaj difficulty in remodelling official 

 methods. In almost all the national systems (the re- 

 ports of the Fishery Board for Scotland are perhaps 

 the only exception) there is an irritating and fatal 

 absence of detail. Pedantic accuracy is unnecessary, 

 even if it were attainable, but every local fishery should 

 somewhere or other be recorded;, as it is, generalised 

 statem.ents only are accessible. It is the continual ex- 

 perience of everyone who attempts to make use of 

 official fishery statistics that the data are inadequate, 

 or ambiguous, or misleading. All this imperfection 

 must necessarily be reflected in the data of the inter- 

 national Bulletin Statistique, and rearrangement of the 

 matter of the latter would only go a little way towards 

 the reconstruction that is so desirable. ' J. J. 



1 "Bu'letin Statistique des Peches maritimes ties pavs du Nord de 

 rRurope." Vol. viii., pour les annies 191 1-12. Edited by Pro*". D'Arcy W. 

 Thompson. (Copenhagen, 1917.) 



