The Finger-Grasp in Sleep.

The finger-grasp was not shown in sleep by A on D. 12, and was absent when Y was tested several times during sleep in the first few weeks. Gesell mentions the absence of the reflex in new-born infants during sleep. But that it may continue during sleep, having started before, is shown in observations on Y. Thus:

D. 16: "With a view to testing the length of the finger grasp and the existence of a 'refractory period' (which Sherrington has shown to be characteristic of reflexes and a means of avoiding tetanus) I inserted my little finger carefully in Y's left hand (when she was having an interval in a meal) and on her grasping it I applied a slight pull. Her grasp continued for 35 seconds, including two periods of specially tight grasping, and then the hand was jerked away. The next grasp lasted only 15 seconds, but she was restless for food. On being placed to the breast she grasped my finger readily again and this time the grasp resisted my gentle pull for 7 minutes without a break though there were slight variations of pressure. At 5 minutes her eyes closed and sucking ceased and she apparently slept, but the grasp continued." Certainly if there is a refractory period in this reflex at this age, it is only in the sense used by Sherrington in referring to heart beat: "To-day, by refractory phase is understood a state during which, apart from fatigue, the mechanism shows less than its usual excitability."

Again on D. 18: "Finger grasp of 10 minutes this morning: (I think this was left hand). Steadier than D. 16, firm all the time with occasional tightenings: not rhythmical, but sometimes coincident with a little excited worrying at the nipple as though in half falling asleep she was losing it. Having apparently slept momentarily several times she seemed to go 'right off' at 8 minutes, and at 10 minutes fingers moved about and hand jerked away (not simple relaxing of grasp)."

The Finger-Grasp in Right and Left Hands.

By the end of the second month in the case of B the reflex was more established in the right hand but not in the left.

D. 65: "He took a very firm grip of my finger with his right hand but only after some time could I get him to do the same with the left, and then it was very lax. Right hand kept hold even when I pulled his hand up and down and sideways."

Later on D. 65: "Again the right hand grip stronger than the left, and left gives way sooner." "The right grips are almost proper; not

quite opposition of thumb to fingers but thumb round end of my finger. I noticed that, as he lay in cot, he was holding his right hand with thumb clenched outside-'boy's grip,' but with left hand thumb inside fingers-girl's grip.'

D. 66: "Both hands 'boy's grip'-later boy's grip in right, 'girl's grip' in left."

With Y the right-hand grasp seemed definitely stronger on D. 13. On D. 23: "Y in bath. Right hand took my finger but I could hardly insert my finger in left hand."

On D. 25 however the left hand gave a 2 lb. pull against a 1 lb. pull of the right later notes to be quoted shortly, suggest that the superiority, if any, definitely passes over to the right.

The tables given by J. B. Watson (op. cit. p. 261) show that on the average, among a group of children, there is little difference between the reflex grasps of the right and left hands respectively. But this is quite consistent with marked differences between the hands in individual cases. It will be seen that the superiority of the right-hand reflex grasp in B was followed by precocity of the right hand, as compared with the left, in voluntary grasping.

THE TRANSITION FROM REFLEX TO VOLUNTARY MOVEMENT.

About B's 10th week, signs appear of deliberate movement of fingers and hand and it is difficult to distinguish the finger-grasp reflex from voluntary movement. Thus, D. 71: "He often holds his two fists together nowadays, and less often bangs himself in the face. Once or twice in this last (9th or 10th) week we have seen him 'rub' an eye, and we hear him scratching his eiderdown in the night, due apparently to opening and shutting of hand. For some time he has grasped his mother's blouse, e.g. when bathing, but this is possibly reflex."

Miss Shinn noted in the 9th week that "the primitive reflex clasping became longer and more attentive, a development in the direction of grasping." (In view of my observations on Y, however, e.g. D. 15, it is impossible to regard the length of the grasp as indicative of voluntary grasping.)

Yet B on D. 75 still shows the reflex grasp in sleep. "Hand-grasp reflex occurs in sleep: though touching on knuckles does not open hand." [Is this (occurrence in sleep) perhaps a good test for reflex (or habitual) as against voluntary nature of an action?]

D. 78: "Shows no desire to take hold of small silver vase. Even the

reflex grasp is slow to-day."

D. 80: “Right fist grip is 'boy's,' left 'girl's' again."

D. 81: "Stroked and grasped at E's hand again while feeding."

On D. 83: "Carries his dress up to his eyes with both hands and gazes at it (shown by marked convergence of eyes). Once got it quite close up to his left eye and held it there till he cried."

So there was possible by now a steady hold, and from now the reflex proper seems to be lost as the power of voluntary movement develops. This period of transition coincides with the period of movement in general of the hand; and of an interest in watching the hand. Thus D. 85: "Carries his dress with both hands into his mouth. Held right fist steady (almost perfect) about 6 inches in front of face, eyes fixed on it, converging."

D. 86: "Looks at right hand again, about 6 inches from eyes, moves eyes to follow the small jerky motions of the hand, though hand very steady on the whole. He is now gazing at blue ribbon held in his hand, he carries it nearer and nearer his eyes, eyes converging to a squint, till he sometimes gets it right against an eye.'

"Looked steadily at small silver rattle when I rattled it. When I put it in his hand he held it still and gazed at it."

D. 88: "E says that he was touching fingers of one hand with the other to-day, looking at them meanwhile."

A photo taken before the end of the 10th week shows the right hand bringing a silver rattle close up to the mouth with sight concentrated on the rattle, while the left hand with arm extended grasps his dress. The note on the photo shows my interpretation at the time: "Beginnings of voluntary movement with right hand, reflex grasp with the left." Several observations suggest this later development of voluntary movement of the left hand corresponding to its inferior reflex powers: e.g. D. 96: "Pencil put in right hand was taken to the mouth almost at once (three times); when put in left was dropped after a few seconds (twice)."

A similar performance was noted in the case of Y on D. 91: "Again fixating left fist, repeatedly over period of several minutes: when it was moved away (not so jerkily as of yore), it was steadily moved up again and gazed at for perhaps 15 to 20 seconds. Meanwhile right hand was grasping dress as B in photo of 10th week."

During this period of the beginnings of voluntary movement the influence of the reflex seems to remain especially in the effect of touch

in stimulating the hand-grip. The earliest voluntary grasping seems to require the accidental touching of the object.

D. 90: "No attempts to grasp object (yellow pencil) held up to him (B), though he looks at it. Touch on knuckles opens right hand."

D. 92: "Looks interestedly at rattle but does not grasp it till it touches his hand; still looked at it when grasped."

Miss Shinn also noted in the 12th week that a touch on the back of the hand suggested grasping. Several notes on B at this time suggest that the voluntary movement of the arms combines with a reflex grasp of the hand at touching an object, to effect what to superficial observation looks like a volitional movement throughout.

The hands naturally, in the course of voluntary or of spontaneous jerky movements, frequently come into contact and they now begin to grasp one another.

D. 95: "Feels his hands and fingers now with his thumb and finger opposed, e.g. taking right finger between thumb and first finger of left hand."

The interference of a reflex grasp with voluntary movement was suggested on

D. 95: "I held silver rattle before his eyes. He was grasping left hand with right and merely gazed at rattle till I held left hand down: then right hand groped about till it touched mine and then moved to rattle and up to mouth."

The development of the power of inhibiting such merely reflex grasping (useless for the purpose of the moment) is evidently one condition of the advancement of voluntary activity. The possibility of interference of a reflex in voluntary movement is shown still more clearly in notes on Y.

D. 130: "Red pencil held in front of her, just in reach. Left hand moved and took hold of it at once. Same repeated: this time her hand caught on to my hand and tightened on it, though gaze continued on pencil. But she failed to loose my hand and carry hand to pencil. So later." Reflex apparently still working inevitably and not within control.

D. 132: "Pencil held in front of eyes: both hands moved up towards it: missed it and clasped one another: clung thus for a time; a grunt and impatient movement of locked hands suggestive of impotence or annoyance. (Later left hand succeeded but let fall at once: right hand succeeded and held.) Again reflex interfering."

A still clearer case of reflex grasp interfering with voluntary grasping was noted on D. 168 in Y.

Med. Psych. VII

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D. 168: "Voluntary movement clearly hindered to-day by reflex grasp. She was holding ring in right hand and putting it to mouth when a straw mat was put on her chair table. This greatly interested her and she put down her hands to it at once repeatedly (still grasping ring), and occasionally bought hands back to the face with apparent disappointment, hands being put down at once again to mat still grasping the ring. After repeated efforts ring finally slipped from her hand, and now mat was immediately grasped and instantaneously carried to the mouth. Left hand had meanwhile part of the time been grasping another ring and afterwards seemed unable to manage to grasp mat alone. More attention seemed to be given to right hand."

SIGHT AND TOUCH CO-ORDINATION

Sight seems to affect the grasping at first by simply providing a stimulus for groping. Thus

D. 95: "Held yellow pencil up. He gazed at it: right hand groped towards mine till it grasped mine, felt resistance of my hand, moved on, grasped pencil and at once carried it to mouth, mouth opening wide long before pencil reached it, mouth and hand acting as one."

Yet touch apparently remains for some time the necessary stimulus for the grasp for on D. 97 I note: "There are no signs of grasping at things seen." But the child is constantly having practice in gazing at things held and moved about, and even in the act of grasping. Thus

D. 100: "Put in cot. Seizes eiderdown edge in both hands, moves them towards one another, then back, sometimes till they touch, gazing steadily at left or right hand. N.B. Still moves the hand he is not looking at. This went on over 5 minutes." And

D. 101: "No attempt to grasp rattle at sight, though he watches grasp when rattle touched."

Suggestions that sight may prompt the groping occur on

D. 98: "Lying in cot, gazing at pink cover: he takes hold of cover with left hand and moves it to and from face. When it slips out of hand he grabs at it again, eyes still fixed in corner of cover. This may be the beginning of grasping guided by sight."

The difficulty of deciding at what stage the sight prompts hand movement and grasp, is due to the constant spontaneous movements of the hands. Thus on

D. 106: "He moved right hand towards pencil, when gazing at it, and grasped it (with thumb opposed). But this hand moving was going on before and pencil was in track between extended arm and mouth."