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ANIMAL BEHAVIOUR, VII, 1 .2

of the pattern or orientation of surface irregu-larities . From this and from the failure of octo-puses to learn to discriminate between objects,such as lamellibranch shells of various species,having different shapes but similar surfacetextures, it can be argued that the animals areunable to distinguish the shape of objects thatthey touch .

This inability seems to be a consequence of theextreme flexibility of the arms of Octopus .Animals, such as ourselves, which can dis-tinguish the shape of objects by touch presum-ably do so by integrating information from theirtactile sensory endings with information aboutthe relative position of these endings derivedfrom sense organs located in their muscles andjoints. The complexity of nervous system necess-ary to do this depends upon the number ofsuccessive joints and the degree of freedom thateach allows .

Octopus has no joints, so that the number ofpossible bending places and positions of itseight arms and two thousand-odd suckers is forall practical purposes infinite. It is most im-probable that the animal has a sensory apparatusof the complexity necessary to define the relativeposition of its armtips, let alone of the suckers,at all accurately. Discrimination experimentsshow that even if such a system exists, Octopusis unable to integrate the information derivedfrom it with that from its surface tactile senseorgans, and so cannot gain additional inform-ation about objects touched by comparing im-pulse patterns from neighbouring groups of senseorgans .

Consideration of the structure of the tactilesensory system in the light of its known proper-ties suggests that Octopus learns to recogniseobjects by the characteristic frequencies thattheir surface textures produce in the nervescoming from the arms, and that the integrativework done by the brain is relatively simple.

The extent to which the structures associatedwith tactile learning are localised in the nervoussystem can be traced by comparing the perform-

ance of animals in training experiments madebefore and after surgical interference with their,brains. Removal of the optic lobes, togethercomprising somewhat more than half of thetotal mass of the brain, has no effect uponOctopus's ability to make simple tactile discrim-inations .

Damage to the vertical lobe-a considerablysmaller volume of tissue-has effects that may bebroadly described as decreasing the efficiency ofthe learning process ; the animal requires moretrials to attain a given standard of response .Removal of further parts of the supraoesoph-ageal brain mass has no appreciable effectupon tactile discrimination until the lesion in-cludes parts of the inferior frontal-subfrontallobe system. Extensive damage to either of thesesmall lobes destroys Octopus's ability to learn todiscriminate between objects by touch, althoughhaving no effect on the execution of movementsof acceptance or rejection.

We can, in fact, take the matter further thanthis and show that there are functional divisionswithin the inferior frontal-subfrontal system . Bytraining the animal to reject an object presentedalways to the same arm, and then changing thearm, we can demonstrate that the effect of ex-perience of one arm does not at once spread todetermine the reactions of the rest ; we have,literally, a situation where "the right hand doesnot know what the left is doing", and it seemswholly probable that this implies the existence ofneurone fields representing individual arms with-in the lobes dealing with tactile integration .Since removal of the inferior frontal-sub-

frontal system does not affect Octopus's visuallearning it is concluded that these parts are ex-clusively concerned with the integration ofsurface tactile information. As this integrationappears to be limited to frequency discrimin-ation, there is reason to believe that the inferiorfrontal-subfrontal octopus preparation willprove to be unusually favourable material for thestudy of learning processes and the structuresassociated with them .

SOCIAL INTERACTIONS IN DISCRIMINATION LEARNINGBY P. KLOPFER

Ornithological Field Station, Madingley; Department of Zoology, Cambridge

A full understanding of the ontogeny of discrimination learning . In this study, learningspecies-specific food preferences requires a rates and processes were compared inn paired andknowledge of the effects of social interactions on

single birds .

PROCEEDINGS OF THE ASSOCIATION FOR THE STUDY OF ANIMAL BEHAVIOUR

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The term "empathic learning" has been pro-posed as a rubric covering all forms of motormimicry. Processes involved may include second-ary conditioning, social facilitation, local en-hancement, or visual imitation . There is evidencesupporting the operation of all these in avianbehaviour, except the last .

Birds (greenfinches, Chloris chloris) weretrained to feed from one of two patterns and toavoid the other, with whole and aspirin-filledsunflower seeds serving as positive and negativereinforcement . Single birds learned the dis-crimination rapidly, as did birds which had beenallowed to observe a previously trained bird per-forming. Birds which were being trained in thepresence of an untrained partner, however, re-quired much longer. When birds of this lastgroup were permitted to observe the training se-

SOME PROBLEMS IN LOCALISATION OF HORMONAL ACTION ON THE C .N.S.By R. WARREN

No precis of this paper was available at the time of going to press .

At an Ordinary Meeting on 23rd September, 1958, held in the Department of Psychology,Birkbeck College, London, the following papers were read . The President was in the Chair .

REFLEX RESPONSES IN FLYING INSECTSBY L. GOODMAN

Queen Mary College,

The initiation of flight, its regulation, main-tenance and cessation all depend upon the in-teraction of a large number of reflex reactions .Some results of an examination, at present inprogress, of the part played by visual stimuli inthe maintenance and regulation of flight and inthe orientation of the flying insect in its environ-ment were described, with special reference tothe behaviour of the desert locust, Schistocercagregaria .

The relationship between the light intensity atwhich the insect was flown and the flight posture,readiness to fly and duration of flight was firstexamined. The locusts were attached by thethorax to a light weight, rigid pendulum capableof movement only in the vertical plane throughthe long axis of the body. They were attached to

quence of their untrained partners, their per-formances repeatedly fluctuated to a random ornondiscriminatory level . The partners, in turn,also fluctuated between random and nonrandomlevels. Behavioural data preclude the operationof local enhancement or social facilitation . Theresults are interpreted to mean that, under theconditions of the experiments, a feeding responsecan be established more readily than an avoid-ance response, apparently as the result of second-ary conditioning (the unconditioned stimulusbeing the sight of another bird feeding) . Thesuggestion is made that birds which show thistype of learning pattern in nature will prove to beconservative in their feeding habits when com-pared with opportunistic species (e.g. Parus sp .)whose learned avoidance responses should bemore stable .

University of London

the pendulum by two rings which allowed free-dom to chose their angle of attack but no move-ment in the rolling or yawing planes. Themounted insect was placed in front of a smallwind tunnel and was enclosed on five sides by awooden box. The light intensity could be set atany desired value, and it was shown that the .angle of pitch, the readiness to fly and the dura-tion of flight recorded over a timed period werenot affected to any marked degree by this factorin Schistocerca gregaria or in Lucilia sericata andMuscina stabulans, the two flies tested. The lightintensity did have a marked effect on night-flyingmoths however, the wing beat frequency beinghigher and duration of flight longer at low in-tensities .

Sudden changes in the surrounding intensity