Conditioned headturning in human newborns as a function of conditioned response requirements and states of wakefulness

JOURNAL

OF EXPERIMENTAL

Conditioned

CHILD

PSYCHOLOGY

13, 43-57

(1972)

Headturning

in Human

Newborns

of Conditioned

Response

Requirements

and R.

CLIFTON,~

States E. R.

as a Function

of Wakefulness SIQKELAND

Brown

AND

L.

I?. LIPSITT

U~wiwsitf/z

This study compared the effects of presenting reinforcement contingent upon headturning for two groups of infants differing as to the response requirements imposed on Ss in the conditioning task (5” vs 15” ipsilateral headmovements). Changes in criterion headturning over conditioning trials for each of the 2 response-contingent reinforcement groups were compared with the performance of random rrinforcemrnt control Ss matched with individual experimental Ss on the number and sequence of reinforcements given over conditioning trials. The study was designed to assess the rela.tionship between newborn conditioning performance and behavioral state ratings of wakefulness, and to compare conditioning performance as a function of differences in the response requirements imposed on infants in the ronditioning task. The apparent contrasting results obtained in 2 previous studies of conditioned headturning with newborn infants suggested the need for further experimental investigation regarding the importance of these variables in conditioning studies with human newborns. Although response-contingent reinforcement, resulted in significantly higher levels of headturning performance than noncontingent reinforcement over conditioning trials, the experimental effect was independent of differences in response requirements imposed on the conditioning task. However, probability of headturning showed a linear relationship to behavioral ratings on a 5-point scale of wakefulness with minimal headturning occurring for both experimental and control Ss on those trials in which 8s were rated as sleeping either “deeply” or “lightly.” In addition an interaction between state in that experimental Ss ratings and experimental treat.ments wa. s obtained were twice as responsive as control Ss on conditioning trials where t’hey were rated as behaviorally “avvake.”

The somewhat contrasting results reported in two tioned headturning with human newborns (Siqueland ’ Present address: Department Amherst, MA 01002. ‘This research was supported by to E. R. Siqueland and NB-04268 to their appreciation to B. Reilly for the staff of the Providence Lying-In

of

Psychology,

Academic

Prms.

Inc.

of

Massachusetts,

National Institutes of Health Grants NB-03386 1,. P. Lipsitt. The aut.hors would like to express her assistance in conducting this study, and to Hospital for their extensive cooperation. 43

@ 1972 by

University

studies of condi& Lipsit~t, 1966;

Clifton, Meyers, & Solomons, 1971) suggested further experimental analysis of procedural differences employed in these studies, differences which may be important to the facilitation of learning processes in infants. Perhaps in descending order of importance, the 2 studies differed with regard to behavioral state requirements in subject selection, response requirements for obtaining reinforcement, and type of nutrient offered as reinforcement. While Siqueland and Lipsitt (1966) selected their experimental 8s from a population of spontaneously “awake” newborns, Clifton et al. (1971) imposed no state criterion for initial selection of infants; instead, all SY received a ‘%ake-up” procedure that brought them to an awake state as judged by 2 raters. In addition, the Clifton et nl. study used a higher amplitude headturning response as the clependent, variable than that employed in the first st’udy. Both of these factors, the inclusion of initially sleeping infant’s and the use of a more difficult response criterion in the second study, would likely result in a lower baseline frequency. Not. only did the results of the second study indicate that infants cla&X as spontaneously awake before the “wake-up” procedure ma& more headturning responses than infants who were originally classified as asleep, but the author:: also noted that a number of their infants made fewer than 2 criterion (and therefore reinforceable) headturns over the conditioning trials. Obviously, such a minimal baseline frequency of unconditioned headturning hy infants in this study resulted in minimal exposure to the reinforcement contingencies over the course of training. To resolve the differences between earlier results, all Se in the present study were spont,ancously awake before the exlteriment. started, and trial by trial ratings on a behavioral scale of wakefulness were used to examine the relationship between momentary 7 states of wakefulness and conditioned performance. Two levels of response magnitude were investigated: a 15” heatlturn that corresponded to Clifton et al. (1971), and a 5” hcaclturn that approximated the response criterion in the first of the 3 espcriments reported by Siquelnnd and Lipsitt (1966). This particular c~spcrimcnt was nearest in design t,o Clifton et nl. Although headturns svcrc not recorded polygraphically in this earlier experiment,, the authors estimated reinforced turns to bc on the order of 5”. Finally, the present study again used glucose for reinforcement, as it, had been used in the original study. METHOD

The 8.5 l)artic*ip,at~ing in tl& study were full-term infants born at the l’rovidcnrr Lying-In Hospital in Providence, RI. Although 48 infants ww seen in the laboratory, only 36 & completed the experimental pro-

COKDITIONED

HEADTURNING

IN

NEWBORNS

45

cedures. Of the 12 exclusions, 3 were due to equipment problems or procedural errors and 9 to failure to meet a beha\-iornl criterion of wakcfulnesa on the initial phases of the experimental proceclure (see deecription of state criterion under “Proce~lure”). The Ss ranged in age from 36 to 98 hr and the mean age was 67.7 hr. Apparatus An apparatus similar to that of Siqueland and Lipsitt (1966) was usccl to obtain polygraphic records of lateral head movements. A Model 1) Grass polygraph was calibrated to provide directional pen deflections of 1 mm with each 2” rotation of the infant’s head. ,4 manually operatccl event marker was used to record presentations of auditory and tactile st.imulation, wit)h the onset and duration of each trial interval recorded on the polygraph record. Each S was placed in a stabilimeter crib housed in a sound attenuated test, chamber (6 X 6 X 7 ft). A Grason-Stadlcr (Model 901B) Noise Generator provided a constant background white noise signal with a sound pressure level of 61 db. The auditory test stimulus was an 80 db low frequency square-wave tone ITit a funclamental component of 23 cps, wit,h a tluration of 5 sec. Procedure The procedures used in t’his study were the same as those used 1)~ Clifton et al. (1971) except for the following changes designed to examine the effects of differences in procedures between the above study and those of Siqueland and Lipsitt (1966). As in the Siqueland and Lipsitt study, only infants who were behaviorally rat’ed as awake in the hospital nursery were brought to the laboratory. These Ss were randomly assigned to the 2 response criterion groups, 5 or 15” turn groups. Within each of these groups, & were designated Experimental or Cont,rol, thus constituting a 2 X 2 design, with 9 8s in each subgroup. As in the previous studies each Control S Teas LLyoked” to a particular Experimental S to control for pseudoconditioning effects. Thus the performance of the Experimental S detcrmincd for the matched Control S the number of reinforcements and the specific test trial on which reinforcement was presented. The present experiment replicated the random control procedure used by Clifton ef nl. (1971) in contrast to the specifically nonpaired prescntat’ion of stimulation and reinforcement used by Siquelancl and Lipsitt (1966). In the latter study the presentation of reinforcement always occurred S-10 set after termination of the auditory and tactile stimulus. [For a discussion of the problem related to the differential effects of the “truly random” and ‘Lspecifitally nonpaired” controls, see Rescorla (1967) & Siqueland (1970) .]

46

CLIFTOX,

SIQUELAND,

AK;D LIPSITT

The present study attempted both to control for and assessthe effects of degree of wakefulness on headturning performance of infants. Two experimenters independently rated each S’s state of wakefulness 5 set prior to each experimental t,rial on a 5-point behavioral scale similar to that employed by Prechtl and Beintema (1964), as follows: State I: State II: State III: State IV: State V:

Deep sleep, indicated by eyes closed, even breathing, no movement. Light sleep, indicated by eyes closed, even breathing, slight movements. Drowsy, indicated by eyes occasionally open, uneven breathing, occasional arm and,/or leg movement. Awake quiet, indicated by open eyes, frequent arm and/ or leg movements, occasional vocalizations. Awake agitated, indicated by crying, tense muscles, frequent limb movement.

To insure that only awake infants were included in the study a behavioral state criterion was adopted, such that ratings of light or deep sleep (Stat,es I and II) for 4 successive trials during the first 12 trials (6 baseline and 6 conditioning trials) disqualified Ss from further participation in the experiment. This behavioral criterion for excluding Xs from the study was adopted after pilot work indicated that a number of infants who were rated as awake in hospital nursery fell asleep almost immediately when they were brought into the experimental laboratory. In fact, 19% of t,he infants brought to the laboratory were excluded from further study by this criterion. The S’s were tested between 7:30 and 9:00 AM, prior to the 9:00 AM feeding. Originally, as in the Siqueland and Lipsitt study, we had also planned to test infants between II:30 and 1:00 PM, prior to the I:00 PM feeding, but it was extremely difficult to find infants in an “awake” state in the nursery during this time, and on many days no infants met t’he study criterion of wakefulness. In addition, of those Ss who were rated as awake during this time period and brought to the laboratory, 44% were rejected for failure to meet, the experimental criterion of wakefulness over t,he first 12 experimental trials. Thus, rtjec.tion of infants from the present study on the wakefulness criterion increased markedly as the temperature and humidity in the nursery increased over the morning hours; consequently, all testing was done between 7:30 and 9:00 AM.~ 3 It should be noted that although the present study was conducted in the same laboratory and infants were selected from the same nurseries as the Siqueland

CONDITIOXED

HEADTURNING

II\:

iXE\VBORh-S

47

The conditioning procedures were similar to those used by Siqueland and Lipsitt (1966) and all Xs received baseline, conditioning, and extinction t’rials consisting of a 5 XC auditory stimulus with a 3 FCC tactile stimulus to the infant’s left. cheek presented 2 SW following the onset of the audit,ory stimulus. All Ss received 6 baseline, 30 conditioning, and 12 extinction trials. For the Experimental Xs the presentation of a 5% dextrose solution via nipple was made experimentally contingent upon the occurrence of each crit,erion ipsilateral head movement. Each yoked control X was equated with his experimental pair on the number and trial sequence of reinforcement presentations. However, for the Control Ss the dextrose presentations were given at random time intervals between the period of tone onset and the beginning of the subsequent test trial. As in the Clifton et al. study the actual time of occurrence of the reinforcement on a given trial was determined by consulting a table of random numbers. The response measure was t,he occurrence of a criterion amplitude ipsilateral headturn during the 5-set interval following the onset of the auditory stimulus. (Siqueland & Li1)sit.t used a 6 set interval including 1 set following the termination of stimulation.) Ss were scored as giving no criterion response on those trials where the initial response to stimulation was a contralateral headturn equal in amplitude to the criterion ipsilateral movement. In addition the criterion amplitude movement of t,he S’s head had to occur within a l-see time interval to qualify as a headturning response (identical to that employed by Clifton et al.). One E sat at the head of the S and was responsible for centering the S’s head prior to each test, trial, presenting the tactile stimulus, and delivering the reinforcement at the designated times. A second E monitored the polygraph for the occurrence of criterion headturns, signalling the first E by means of a flashing light 2 set prior to each test trial, and when reinforcement was to be delivered to the S.

and Lipsitt, study, Siqueland and Lipsitt conducted their study in the fall and winter months while the present study was conducted during July and August. Marked differences in the behavioral states of infants in both the hospital nursery and laboratory were noted by the authors of the Siqueland and Lipsitt study when pilot work on the present study was initiated. Although the laboratory was airconditioned, the hospital nursery was not. During the course of the study the average temperature and relative humidity readings in the hospital nursery at the time of testing were 80” and 64%, respectively, with contrasting readings of 77” and 49% in the experimental situation. Although the temperature differences between the nursery and the laboratory varied only 2 or 3” (always cooler in the laboratory), the humidity difference was notable.

48

CLIFTON,

SIQUELAND,

AA-D

One other change in the present study, studies, was the use of an artist’s number the E's finger to present the 3 set tactile change was instituted to provide a more

LIPSITT

in contrast to the 2 previous 6 camel hair brush rather than stimulus to the S’s cheek. This standardized tactiie stimulus.

RESULTS

The number of ipsilateral headturns made by each X during Baseline, Conditioning, and Extinction trials was blocked into 3 trial units. These data were used in all analyses reported. Figures 1 and 2 present the average responses over all trial blocks for the 5” and 15” response criterion groups, respectively. An all-subjects analysis of variance on Base plus Conditioning trials yielded a significant main effect of treatment groups (F = (1,32)5.09, p < .05), indicating the Experimental Ss made more headturns than Control 8s. In addition, the Trials X Treatments (F = (11,352)2.30, p < .05) and Trials X Degree Groups (F = (11,352)2.20, p < .05) interactions were significant. Newman-Keuls follow-up tests compared these groups on each trial block over Base and Conditioning trials. For the Trials X Treatment interaction, the Experimental A’% showed significantly more headturning than Controls on Condit,ioning blocks, 2, 4, 7, 8, and 10. There were no differences between t,he Experimental and Control Ss during Base trials. For the Trials X Degree interaction, the 5”

I

I

2 sasi

1

2

3

4

5

1. Comparison and control

7

CONDITIONING

THREE-TRIAL FIG. mental

6

8

9

IO

ALI

I

2

3

4

EXT’NCTION

BLOCKS

of the mean percent response groups over baseline, conditioning

for the 5” headturn experiand extinction phases.

COSDITIONED

I

BASE

HEADTURNING

2. Comparison and control

49

NEWBORNS

” CONDITIONING

THREE-TRIAL FIG. mental

IN

-i IXTINCTION

BLOCKS

of the mean percent. response groups over bwselinc, conditioning

for

the 15” headbrn experiand extinction phases.

headturn Ss showed significantly more headturning than the 15” Ss on Base trial blocks 1 and 2, and Conditioning trial blocks 3 and 4. Similar analyses of variance were performed on Extinction trials alone and on Extinction plus the last block of Conditioning. None of the effects was significant. The procedure of excluding S’s from the study who failed to meet the behavioral criterion of wakefulness during the Base and first 6 Conditioning t#rials provided a homogeneous population of awake infants during the init.ial stage of the experimental procedures. However, this procedure did not insure t.hat the infants remained awake for the duration of the experimental procedure. Even with a very conservative behavioral measure of st,able sleep defined au 12 or more consecutive trials on which a S was rated in “light’ or “deep” sleep (States I and II), 17 of 36 infants were rated as sleeping by the end of the experimental procedures. Although there were trial by trial fluctuations in the individual Ss’ ratings on wakefulness, there was a strong tendency for infants to remain in a sleeping state following a few consecutive trials on which t’hey were rated as sleeping (States I and II). For the purpose of a further analysis of the relationship between behavioral ratings of wakefulness and headturning 1)erformnnce on the Experimental and Cont.rol groups, S’s were classified as either ‘Lawake” or “:&eel)” on the basis of their state ratings during the last, half of the conditioning trials. Thus,

50

CLIFl’OK,

SIQCELAND,

AND

LIPSIlT

infants who received an average state rating of less than 3.0 over conditioning trials 16-30 were classified as “asleep.” If the average state rating was 3.0 or greater, the S was classified as “awake.” This procedure resulted in unequal X’S for the 4 subgroups. The average responses for each of the 4 subgroups over all trial blocks are presented in Figure 3. An unweighted means analysis of variance was used to analyze these data (Winer, 1961, pp. 242-243, 375-376). As expected, this analysis duplicated the previous results on Base plus Conditioning trials, in that there was a significant main effect of Treatment groups (F = (1,28)4.74, p < .05), and significant interactions of Trials X Treatment. (F = (7,196)2.14, p < .05) and Trials X Degree (F = (7,196)2.66, p < .05). In addition, there were main effects of trials (F = (7,196)4.71, p < .Ol) and degree groups (F = 11,28)4.25, p < .05). However, the most pertinent finding in the analysis was a significant effect of state (F = (1,28)6.60, p < ,025) indicating that “awake” Xs responded with more headturning than “asleep” 8s. Although none of the interactions of state and experimental treatments was stat,istically significant, it is still of interest. to compare the performance of the awake and asleep infants within the experimental

m O--

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EXP

AWAKE

EXP

ASLECP

N=l

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N=7

o--

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CONTROL

AWAKE

CONTROL

ASLEEP

N:3 N:9

_1 503 2 F

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SIX-TRIAL FIG. 3. Comparison of the mean conditioning and estinct.ion phasvs: “asleep” or “awake.”

l A. _ \ -i. \ > ,Js, \ ‘,’ <;’ I 9 5

I

2

EXTINCTION

BLOCKS

percent response for 4 subgroups over baseline, Experimental and control groups classified as

COKDITIOXED

HEADTURNING

IN

NEWBORNS

51

and control treatments shown in Figure 3. Comparing Experimental and Control Ss over the initial conditioning trials the Experimental Ss made more headturning responses than Control Ss; however, for those Experimental Ss who were classified as asleep over the last half of the conditioning trials, performance was not differentiated from that of the awake Control Ss. All Ss irrespective of subsequent changes in wakefulness over the course of conditioning trials had to meet a behavioral criterion of wakefulness on the initial conditioning trials to be included in the study. It was only those Experimental Ss who fell asleep over t,hc latter stages of conditioning that failed to be differentiated in their headturning pcrformance from the Control Ss. When comparisons are made between the performance of awake Experimental and awake Control Ss, the Experimental Ss were consistently responding at, a higher level t8hroughout the course of conditioning. Although the above method of classifying individual Ss into subgroups of awake and asleep infants allowed for further statistical analysis of the relationship between condit’ioning performance and behavioral states, it provided a relatively crude assessment of the influence of behavioral st’ate on headturning performance. Irrespective of their classification as awake or asleep based on state ratings during the last half of the conditioning trials, all Ss were rated as behaviorally awake during the early stages of conditioning. Also, 5 of the Experimentally Awake Ss were rated as sleeping during extinction t’rials. The behavioral state ratings obtained immediately preceding each trial allowed for a further assessment of the effects of state on the probabilities of unconditioned and conditioned headturning in the experimental trials. The Experimental and Control groups were compared with respect to the number of headturns they made within each of the 5 classifications of state relative to the total number of trial presentations given when Ss were rated as being in that particular behavioral state. Thus, response rat,ios as a function of state of wakefulness could range from 0.0 (no headturns) to 1.0 (a headturn occurring on every trial). Table 1 compares the Experimental and Control groups on their response ratios (probability of a headturn) over the 5 behavioral categories of wakefulness. As seen in Table 1, the infants showed increasing probabilities of making a headturning response with higher levels of wakefulness, and this positive correlation between responsiveness and wakefulness held for both Experimental and Control groups. More importantly, the data also suggest an interaction between state of wakefulness and conditioning effectiveness. On those trials where Ss were rated as sleeping (States I and II), there were minimal differences in the headturning performance of the two groups and when Ss were classi-

52

CLIFTOS,

1

SIQUELASD,

AKD

000

LIPSITT

.ooo

a Ratio computed as number of headturns divided by nllmber of trials Ss were classified in that behavioral state.

fied as “sleeping” deeply (St,ate I) neither group made a hingle headturning response. However, on trials where Ss were awake, differences in the Experimental and Control groups are clearly revealed with Experimental Xs twice as responsive as the Control Ss in St,ates IV and V. DISCUSSION

These results provide reliable evidence of conditioned headt,urning behavior in human newborns. While the Experimental and Control groups did not differ in the amount of headturning in baseline, a rapid separation of these groups occurred over the early st,ages of conditioning, and infants who received response-contingent reinforcement responded at a significantly higher level than infant.s who receirecl random presentation of reinforcement. While the conditioning effects obtained in this study were not as stable as those previously reported by Siqueland and Lipsitt (1966), they are contrasted with the negative results obtained by Clifton, Meyers, and Solomons (1971). In t,he 2 &dies where positive conditioning effects were obtained a population of “awake” infants was selected, whereas largely negative results were obtained when no behavioral criterion of initial spontaneous wakefulnesswas adopted. Differences in responserequirements wcrc also manipulated in this study. While the 5” headturn group performed better than the 15” group during baseline and early conditioning, there was no reliable difference between the groups at, the end of t,raining. In cont.rast t.o studying the effects of response requirements on learning, a variable that can be experimentally manipulated, assessmemsof the effects of state variables pose a more difficult problem in experimental studies with infants (Escalona, 1962; Gentry & Aldrich, 1948; Hutt, Lenard, & Prechtl, 1969; Papousek, 1967; Papousek & Bernstein,

CONDITIONED

HEADTURKING

IN

iX;EU’BORKS

53

1969; Wolff, 1966). Hutt et al. have provided an excellent review of problems that variations in states of wakefulness present for investigators interested in assessing the infant’s capacity to process exteroceptive stimulation. It is clear from their review of relevant studies that there are independent fluctuations in the various behavioral and physiological measures that investigators have employed to assess the complex phenomenon of “arousal,” LLwakefulness,” or “vigilance.” However, even when investigators have used a relatively gross descriptive behavioral measure of “wakefulness” similar to the one employed in the present study, they have found that the probability of eliciting relatively simple reflexive responses varied as a function of their state ratings and that the optimal behavioral state for eliciting one reflex was not necessarily optimal for other reflexes (Lenard, von Bermuth, & Prechtl, 1968). Thus, any specification of “optimal state” will depend on the specific classes of elicited or spontaneously occurring behaviors that are investigated and also on the purpose of the experimental investigations. Escalona (1962) has recommended that the researcher should first determine experimentally how state affects the part’icular variable under investigation, then in subsequent studies accept only those Ss in a specified state which interacts in known ways with the variable of primary interest. However, the selection of Ss according to a specified state criterion not only will affect the initial values of the particular variable under investigation, but changes in these values will be correlated with changes in stable st,ates of infants that occur over relatively brief experimental procedures. Depending on the purpose of the invest,igation, this change from initial baseline levels that are correlated with state changes may be biased for or against the changes in response predicted by the experimental phenomenon under investigation (e.g., increased responding in conditioning studies and decreased responsiveness in habituation studies). In instrumental conditioning paradigms of the type employed in conditioned headturning studies, some minimal baseline probability of headturning must occur if the X is to be afforded an opportunity to be presented with the contingency bet,ween response and reinforcement. Given the requirement of wakefulness for the occurrence of headturning behavior and the difficulty in maintaining wakefulness as a stable state, baseline changes in response occurrence which correlate with decreased wakefulness bias the infant toward decreased levels of responsiveness over t.ime. The trial by trial assessments of state employed in t,he present study are of particular interest in that they allow for comparisons of Experimental and Control groups on probability of response occurrence given that they were rated in comparable states of wakefulness on a specific test trial. The results of this study show that no headturning to

54

CLIFTON,

SIQUELAND,

AND

LIPSITT

tactile stimulation occurred in either the Experimental or Control groups when Ss were rated as “deeply sleeping,” State I. Furthermore, these groups showed negligible increases in headturning when they were rated as “sleeping lightly,” State II. These findings are consistent with the results of Lenard, von Bernuth, and Prechtl (1968)) who reported that exteroceptive reflexes in the newborn were almost totally absent during regular sleep, and weak during irregular sleep. It is clear from the results of the present study that state as an organismic variable not only had a marked effect on the baseline probability of conditioned headturning behavior, but it also influenced the effectiveness of experimental treatments. Results shown in Table 1 indicate that, it was only on trials when infants were rated as behaviorally awake that the Experimental Ss made more headturning responses than the Control 8s. Given a state rating of 4 or 5, the Experimental S’s made twice as many headturning responses as the Control Ss who received the same behavioral state ratings of wakefulness. It should be noted that although headturning was correlated with state ratings on wakefulness, the selection of awake Ss did not insure some minimal baseline of criterion headturning in all 8s. Four infants in the present study failed to make a single headturning response over the course of the experimental trials and 3 other Ss made fewer than three responses over conditioning trials. The extremely low baseline of unconditioned hcadturning by these infants would provide minimal exposure to the reinforcement contingencies and thus little opportunity for learning to occur. In addition to excluding sleeping infants, the results of this study would suggest that future investigat’ions of conditioned headturning in newborns should insure that all infants included in the experimental population demonstrate some minimal baseline of criterion responding over the initial conditioning trials. To enable this, 3 alternatives for future investigations are suggested. The investigator can select his experimental population by excluding infants who fail to meet some minimal criterion of responding. On the other hand he may attempt to adjust or select a response criterion in such a manner that all infants demonstrate t#hat the response is initially part of their unconditioned behavioral repertoire (i.e., smaller amplitude turns of 2” rather than 5” arc). It should be noted that any developmental comparisons of learning ability require that differences in learning are not, attributable to differential response capacities of the different age groups (for further discussion of this problem the reader is referred to Siqueland, 1970). Finally, the last alternative open to researchers is to employ a procedure of shaping the criterion response by reinforcing progressively larger amplitude headturning responses over the initial stages of reinforcement training.

CONDITIONED

HEADTURNING

IN

NEWBORNS

55

This last procedure was employed by Siqueland (1968) in a study of free operant headturning with newborn infants. Recent findings reported by Papousek and Bernstein (1969) add to the complexity of the problem of state change as a variable in conditioning studies. Based on the results of their studies of conditioned headturning they have suggested that changes in state are elicited by the conditioning stimulation itself and that change in levels of vigilance or wakefulness can be a learned phenomenon. While their conditioning study extended over several clays, conditioning in the present study was examined with a single conditioning session. Within the context of the relatively brief conditioning procedures used in the present study there was no evidence that differential changes in general state of wakefulness occurred as a result of the differential treatment conditions. In comparing t.he changes in state ratings over the conditioning trials for the Experimental and Control groups we found no evidence of reliable differences for t’hese groups. Despite the negative findings in this study with respect to state change attributable to conditioning effect’s, the suggestive findings reported by Papousek and Bernstein (1969) indicate that state changes as a conditioning phenomenon in newborns merit further study. Finally, a recent study (Simner, in press) strongly suggests that such environmental factors as temperature and humidity are correlated with differences in 8s’ responsivity to stimulation. Simner reported evidence of reliable seasonal differences in the newborn’s responsiveness to auditory stimulation with month by month comparisons showing that responsivencss increased during the colder months and decreased during the summer months. Both the present investigators and Simner utilized the same laboratory facilities at the Providence Lying-In Hospital, and the Ss for both studies came from the same hospital nurseries. Using a similar criterion of selecting “awake” infants from these nurseries and testing during t.he morning hours, Simner found that his Ss demonstrated their lowest level of responsiveness in the experimental situation during the 2 summer months in which the present study was conducted. The earlier studies (Siqueland and Lipsitt, 1966) were conducted during the late fall and winter months; in contrast to the present study, little difficulty in finding and maintaining awake Xs was experienced. The infants in all of these studies were housed in a nursery environment that had neither constant temperature not humidity control. Based on his finding of a consistent positive correlation between the autonomic level of arousal of his Ss and their probability of responding to auditory st,imulation, Simner suggested t’hat the reliable seasonal differences obtained may reflect differences in the arousal states of his infants at the

56

CLIFTON,

SIQGELA?;D,

AI’CD

LIPSITT

time t,hey were brought into the laboratory. Based upon the carefully documented seasonal differences obtained by Simner, as well as the apparent differences in stable states of wakefulness observed in the two studies of conditioned headturning in this same laboratory, we would conclude that future experiment’al studies with newborns should be careful in establishing both the baseline states and levels of responaivity to Amulation of their infant population in the immediate experimental contest. To the degree that, environm&al factors such as ambient temperature and humidity may influence the stable state cycles of infants in their caretaking environment (,4ldrich, Sung, & Knop, 1945; Hey & Rlaurice, 1968; Parmelee, Bruck, & Bruck, 1962), correlated changes in state and rcsponsivity map be reflected in experimental situations. REFERESCES ALDRICH,

C. A.,

munity

SUNG,

phase.

C., C

Jownnl

KNOP,

C. Tllc: crying of nemly horn babies. I. The Corn-

of Pwliafrics,

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li~xwi1,.4.

cholr&xl

R

;2. Pavlovian lie&w. 1967,

conditioning 74, 71-SO.

and

its

proper

c*ont,rol

prorc~dures.

Ps!/-

COSDITIONISD

HEADTURMNG

IN

M. I,. The ncwl)orn’s wsp~~~se to the cry of nnoth(‘r Psychology. 1971. 5, 136-150.

SIMNEX.

SIQUELAND.

E.

It.,

8: TDSITT,

Joztrnrrl of EspekmwtaZ WOLFF,

P. H.

The

Psychologicnl

causes,

T,. P. Conditioned

57

NEWBORNS

infant.

headturning in 1966, 3, 356-376. and organization of behavior (1, Whole 50. 17).

l~eveloprrkental

human

newborns.

Child Psychology, control,

ls.s~res, 1966, 5,

in

the

neonate.