George Peabody College, Nashville, Tennessee 37203. A portable apparatus for studying infant head movements and programming sensory stimulation is.
Behavior Research Methods & Instrumentation 1974, Vol. 6,No. 3, 338-340
A portable system for studying head movements in infants in relation to contingent and noncontingent sensory stimulation* PETER VIETZE, MARTHA FOSTER, and STEPHEN FRIEDMAN George Peabody College, Nashville, Tennessee 37203 A portable apparatus for studying infant head movements and programming sensory stimulation is described. Remote push buttons allow observation of vocalizations, smiles, and visual attention. Lightweight and compact, the system allows recording of data in a variety of locations, including home, hospital, and laboratory.
Research utilizing head turning responses in conditioning studies have employed elaborate and sometimes cumbersome apparatus to detect and record responses (e.g., Siqueland, 1964; Caron, 1967; Papousek, 1967; McKenzie & Sack, 1970). These methods involve attaching a harness or headband to the infant's head in order to detect rotations mechanically or telemetrically. More recently, Watson developed a pillow that allows the detection of undifferentiated head or leg movements through changes in air pressure produced by the infant's movements (Watson & Ramey, 1972; Vietze, Watson, & Dorman, 1973). A feature of the Watson system is that the infant is not restricted by the detection device. Watson also developed an electronic interface that allows the E to collect data in settings other than the laboratory and to employ parents as Es with relatively little training. This apparatus has been used to study changes in head and leg movements under conditions of both contingent and noncontingent sensory stimulation (Watson & Ramey, 1972; Watson, 1972;Vietze, Watson, & Dorman, 1973). The present system was developed to study directional head movements in relation to contingent and noncontingent sensory stimulation incorporating the nonrestrained characteristic and portability of the system developed by Watson. The apparatus was designed to meet the following needs: (1) portability to permit studies of response-dependent and response-independent stimulation of infants in a variety of settings including their own homes: (2) minimal direct contact between infant and the electronic devices or restraining headgear that might seem aversive to parents; (3) possibility of recording and control of directionality of head movements; (4) flexibility in position of infant during experimental sessions. With these considerations, an air-pressure sensing system was developed consisting of an air pillow to detect head movements, an electronic *The development of this apparatus was supported by the National Program for Early Childhood Education (Subcontract No. 70-006). We wish to thank Haro..' Stone for his help in the design of this apparatus.
interface, and a stand with which to present visual or auditory stimuli. This system has been used to study instrumental learning and responding to response-independent stimuli (Vietze, Friedman, & Foster, 1974; Foster, Vietze, & Friedman, 1973; Foster, 1973; Vietze, Foster & Friedman, 1974). AIR PILLOW The air pillow consists of two chambers between which the infant's head can be placed so that movement in either direction causes a change in air pressure in the appropriate chamber. The chambers are small football bladders (Model SR 1541), manufactured by the Seamless Rubber Company, New Haven, Connecticut) folded to a rectangle measuring 4 x 5 in. and placed inside pillow cases of the same dimensions. The cases are sewn shut or fastened with Velcro strips. Each pillow case has an extension with sewn Velcro strips attached in order to allow for adjustments to the infant's head size (see Fig. 1). The pillow chambers are inflated to .065 lb/sq in., the maximum pressure for triggering the pressure switches. When the pillows are inflated to this pressure, a head movement of .02 lb/sq in. triggers the pressure switches. These pillows allow the infant's head to be placed so as to touch each of the two chambers. Thus initially centering the head and fixing the distance between the pillows by attaching the Velcro strips serves to insure that movement in either direction is recorded and reinforced.
DISPLAY STAND The display stand is constructed of aluminum channel tubing and consists of three pieces and a base. Two of the pieces fit (one inside the other) and form an adjustable vertical pole; the third piece is welded to the top of the pole at a right angle and extends horizontally over the base. The shape is that of an inverted "L." At the end of the horizontal beam, a 15 rpm Hurst Motor (PCSM) is fastened along with a light bulb socket. In addition, a two outlet junction box is fastened to the
338
STUDYING HEAD MOVEMENTS IN INFANTS
339
no direct electrical connection between the display stand and the infant's crib. The use of 110 V to operate the display stand is no more dangerous than having any other device (e.g., radio, television, clock) close to the infant's crib. CONTROLSYSTEM The control system interface between the pillows and the display stand incluees the necessary integrated circuitry, two fluidic s .itches, three timers, two I IO-V-output receptacle: and a remote control pushbu110n (see Fig. 2 and Table 1). The two fluidic switches (Pitney Bowes-608-0 I-SO) are connected to the air pillows by 1/8-in.-diam vinyl tubing. There is no electrical conductor between the air pillows and the control box; parents are easily convinced that no danger is involved. Each of the two fluidic switches can be set to control one or both of the output receptacles. Thus, infants can be presented discrimination problems with two different stimulus events being contingent on left or right head turns. Any electrical device that operates on 110 V (such as those on the display stand) can be plugged into the control system. The control system has six different modes of operation (see Table 2) with the output being dependent upon or independent of activation of the fluidic switches by head turns. The duration of the output connected to each receptacle is controlled individually by a timer that can be set in Y2-sec steps from Y2 to 5 sec. The third timer controls the length of the interval between output onset
,
'----_~~
J
Fig. 1. Infant in pillow.
top of the horizontal beam. Any electrical device requiring 110 V ac can be operated from this outlet in conjunction with the motor or light, or neither. Each outlet can be operated from one of the two output receptacles on the control box. The motor has been used to display rotating mobiles and other toys which attract the infant's attention. Any cassette tape recorder that operates on 110 V ac can be plugged into the display stand in order to provide auditory stimulation. There is NOR =NORGATE BUF =BUFFER INV INVERTER F·F "FLIP-FLOP
+ 24VOC
=
+24 VOC
24VOC
'"
+24 VOC
Fig. 2. Function diagram for electronic interface.
340
VIETZE, FOSTER AND FRIEDMAN
in the response independent mode (time). Each of the timers can be set to follow a regular or a random pattern. A Rustrak 292-4 four channel event recorder records the frequency and duration of pillow and pushbutton activations. The pushbutton has been used to monitor infant visual attention or vocalizations during conditioning. An eight-channel event recorder can be substituted if additional pushbuttons are desired in order to monitor a greater number of behaviors during conditioning. This requires only minor modification of the present design. The apparatus is presently being used in studies of infant learning and perception, with Ss randing in age from 3 days to 14 weeks in homes and in the laboratory. While smiles, vocalizations, and visual attention are measured by Os using the remote pushbutton, the control system records duration and frequency of head moves as well as incidence and duration of reinforcing stimuli. The control box and event recorder fit easily into a small overnight suitcase. The system is lightweight, easily transportable, relatively simple to operate, and not aversive to parents. Table I Parts List for Figure 2 Number Needed
Transistors
3 2 4 3 2 5 3 2
6 5
470515% 10K5% 1 W
Resistors
Capacitors
Rectifiers Potentiometer Transformers Diodes Relays Switches Heat Sink
A
Head move to one side produces stimulation. Two output channels are activated, if desired. B Head move to one side operates one output channel, head move to other side operates second output channel. Thus, two different sources of stimulation could be differentially controlled by contralateral head turns. Time Response-independent output produced on timebased schedule. Onset duration varies from 1/2 to 5 sec; inter trial interval varies from 1 to 10 sec. AlB Allows for response chaining with possibility that each response produces separate stimuli. Head turn to one side must precede a turn to the other side in order to receive second stimulus. Synchronous Duration of head turn to either side controls duration of stimulation. A and B Head turn to either side produces stimulation.
Although currently being used in experimental research, this system may be useful with physically handicapped infants in increasing and strengthening motor behavior (e.g., leg movement). Auditory and/or visual stimuli could be presented contingent upon movement of specific body parts in order to encourage a handicapped infant to exercise weakened limbs.
5
MC724P MC780P MC 790P MC 789P MC724P MC nop MC725P MC 799P MC726P Fairchild 2N3053
Integrated Circuits
Table 2
Modes of Operation for Control System
1
30K 5% 1 W 5K 5%%W 20K5%%W .15 mfd 10% Elect-l00 V de .05 mfd 10%·Elect-l00 WV de 25 mfd Elect 10% 25 WV de .1 mfd 10% Elect 600 V de 2000 mfd Elect 50 WV de 500 mfd Elect 25 WV de 3000 mfd Elect 50 WV de IR 50FB2L IR 18D82A U-19 Triad-F 41X Triad-P 614BRI
I 1 1 3 2 3 2 1
IN3254 Allied Control CC-66 SPST DPST
2 2
Fluidic 10 A 51 Ld
Wafer 7 pole nls HM-l Estimated Labor Time: E h Approximate Cost of Pal,,: $200
1 1 1
1 1
1
1
4 1 2 5 1
---------
REFERENCES Caron, R. F. Visual reinforcement of head-turning in young infants. Journal of Experimental Child Psychology, 1967, 5, 489-511. Foster, M. Habituation of response-independent stimuli: The relationship between learning and attention in early infancy. Unpublished doctoral dissertation, George Peabody College, 1973. Foster, M., Vietze, P., & Friedman, S. Visual attention to non-contingent and contingent stimuli in early infancy. 8Ist Proceedings of the American Psychological Association, 1973, 8,93-94. McKenzie, B., & Sack, K. H. A telemetric method for measuring and recording head rotations in human infants. Behavior Research Methods & Instrumentation, 1970, 2, 173. Papousek, H. Experimental studies of appetitional behavior in human newborns and infants. In H. W. Stevenson, E. H. Hess, and H. L. Rheingold (Eds.), Early behavior: Comparative and developmental approaches. New York: Wiley, 1967. PP. 249-278. Siqueland, E. R. Operant conditioning of the head turning in four-month infants. Psvchonomic Science, 1964, I, 223-224. Vietze, P., Foster, M., & Friedman, S. Response differentiation in infants: A sex difference in learning. Perceptual & Motor Skills, 1974, in press. . Vietze, P., Friedman, S., & Foster, M. Non-contingent stimulation: Effects on infant visual and motor behavior. Paper presented at the Eastern Psychological Association, Washington, D.C., May 1973. Perceptual & Motor Skills, 1974, in press. Vietze, P., Watson, J. S., & Dorman, L. Extended infant learning: A comparison of two responses and two visual reinforcers. A paper presented at the Society for Research in Child Development, Philadelphia, 1973. Watson, J. S.. & Ramey. C. T. Reactions to response-contingent stimulation in early infancy. Merrill-Palmer Quarterly of Behavior & Development, 1972, 18, 219-227. Watson, J. S. Smiling, cooing and "the game." Merrill·Palmer Quarterly of Behavior & Development, 1972, 18. 323-339. (Received for publication July 3, 1973; revision received January 4, 1974.)
