shock of 0, .15, or .80 mA according Tonic immobility as a fear response in lizards to group designation, Immediately after the receipt of shock, each lizard was immobilized on a table by (Anolis carolinensis)* inverting i t on its back and m a i n t ai n ing manual restraint accompanied by moderate pressure for 20 sec. Manual restraint was applied PATRICIA H. EDSON and GORDON G. GALLUP, JR. by placing one finger at the base of the Tulane University, New Orleans, La. 70118 tail and another on the lower jaw, Duration of self-paced immobility was The role offear in mediating the immobility response was studied in three measured from the time restraint was experiments with a total of 71 anoles, In the first experiment, a significant terminated until the righting response relationship between level of preinduction shock and duration of immobility was occurred, with the E sitting about .6 m found. Experiment 2 revealed a significant effect of brief exposure to a loud away. A 30-min ceiling was imposed noise on the resulting duration of immobility. In the third experiment, lizards on the duration of each reaction as an immobilized in the visual presence of'an E showed Ionger reactionsthan those economy measure. If, for any reason, a immobilized from behind a barrier. The findings were taken as support for a fear lizard did not become immobile Interpretation of animal hypnosis. following the initial application of manual restraint, it was given successive 20-sec inductions until a Although the tonic immobility or young chickens given electric shock state of immobility obtained. hypnotic response has been found in prior to manual restraint remained Results many different species, it has been immobile significantly Ionger than The results of the first experiment studied experimentally in onlya few. controls given no shock. In the present indicate that the duration of To date, no more than three or four study, it was hypothesized that the immobility was related to intensity of published studies .have appeared on duration of tonic immobility in the preinduction shock. The mean lizards. Theimmobility response in the anole would bear a relationship to the durations of immobility were339.6, anole (Anolis carolinensiss was first amount o f preinduction shock, 516.2, and 778.7 sec for control, investigated by Hoagland (1928a, b). consonant with the fear hypothesis. low-shock, and high-shock groups, Hoagland attempted to manipulate the Subjects respectively. Due to appreciable response chemically and found that The Ss were 39 mature A. heterogeneity of variance, raw scores injections of adrenalin tended to carolinensis of both sexes which were were transformed (log1 0 ) for purposes prolong the immobility e pisode. A collected locally.The lizards were of analysis and a between-groups more recent report of tonic captured after dark through the use of analysis of variance revealed a immobility by Prestrude & Crawford head-mounted spotlights to aid significant main effect of shock (1970) used the lizard, lguana iguana. detection. Ss were randomly divided (F = 3.59, df = 2/36, p < .05). The They fo und that the green iguana was into groups of 13 and housed in mean number of inductions required a good source for studying animal individual glass bowls. Room to elicit immobility was unaffected by hypnosis, and, in spite of repeated temperature was maintained at shock, with means of 1.15,1.08, and handling, none of their anirnals failed approximately 70° and 80° F during 1.08 for the control, low-shoek, and to exhibit the response; however, no the dark and light cycles, respectively. high-shock groups, respectively. attempt was made to manipulate the The photoperiod in effect throughout EXPERIMENT 2 reaction experimentally or to test any consisted of 12 h of artificial light. As a possible criticism of the hypothesesconcerning its significance. Food in the form of mealworms and preceding .experiment, Gallup, Nash, Recently, the idea that tonic also water were made regularly Potter, & Donegan (1970) suggested immobility may be mediated by fear available. All Ss were maintained in that shock applied to chickens might has received extensive experimental the laboratoryfor 1 week prior to produce confounding physiological support from work with domestic testing. changes (e.g., .tetany) which could, chickens. These studies (e.g., Gallup, Apparatus themselves, increase or exaggerate Rosen, & Brown, 1971) suggest that Testing equipment consisted of a immobility. To circumvent this tonic immobility in the chicken may Foringer s h o c k generator problem, they used loud noise as an be an innate fear response which has (Model 591-14N) wired to two solid alternate method of producing fear evolved to meet the dernands of copper .wires extending 8 cm from the and found an enhanced immobility p r e d ato r-pre y r elationships. The end of a narrow wooden dowel which response resembling that produced by present study represents an attempt to measured 28 cm in length, The copper shock. Since increasing shock levels look for comparable effects of wires, which were used to adrninister increased duration of immobilityin e x p e r i m e n tally induced fear on sho c k , were parallel and the lizard, it was expected that immobility reactions in A. approximately 1 cm apart at their exposure to a loud preinduction noise carolinensis. point of contact with a lizard. The would likewise prolong the duration of EXPERIMENT 1 duration of each immobility episode immobility by increasing fear. The immobility response has been was timed with a stopwatch. Method explained by several investigators as an Procedure The Ss were 20 mature anoles innate fear response (e.g., Ratner & Groups were designated randomly collected asin Experiment 1 and Thompson, 1960; Salzen, 1963). In as control, low shock, and high shock. divided randomly into noise and support of this interpretation, Gallup, To overcome skin resistance, each no-noise groups. All lizards were Creekmore, & HilI (1970) found that lizard's back was swabbed with saline maintained identically to those in the solution prior to administering shock. previous experiment. Testing consisted of placing the copper A portable signal horn (Sears *Appreciation is expressed to T. J. electrodes on the back of a lizard, Aerosol Power Pack) which generated Q'Brien for help in collecting the lizards. Requests for reprints should be sent to the about halfway between the neck and a low-frequency sound of 126 dB, as second author. base of the tail, and applying a 2-sec measured by a General Radio

Psychon. Sci., 1972, Vol. 26 (l) 27 sound-level meter (Model 1551-e), was Method that the E may be a potent source of used as the sound source. The Ss were 12 mature anoles of variation in studies of anirnal hypnosis. To control for noise contamination, both sexes obtained similarly to those Contrary to the speculations of testing was conducted in aseparate in the previous experiments but Prestrude & Crawford (1970), who room. Due to the large within-group maintained in the laboratory for only tend to favor a cortical inhibition variability found in the first 1 day prior to testing. account, these three experiments with experiment, pretest habituation The apparatus was a 50 x 52 cm A. carolinensis provide direct support procedures we.re employed. On each of plywood barrier, with a small one-way for a fear interpretation of animal the 3 days prior to testing, each lizard wide-angle lens inserted in the middle, hypnosis in lizards. Additional support was carried to the test room in its which was mounted on one side of the is provided by data from the third individual container and immobilized table used for induction. experiment for the notion that the five times, with a 45-sec intertrial Using the same procedure described presence of a potential predator can interval between successive inductions. by Gallup, Cummings, & Nash (1971), substantially influence the hypnotic H, on any habituation trial, the half the Ss were restrained with the E response. Thus, conceptualizing tonic response lasted longer than 60 sec, it sitting in clear view (approximately immobility as a fear response, which was terminated by gently prodding the .6 m away from the S), whe.reas for under natural conditions may be animal. the remaining six lizards, the E was related to predation, appears to hold On the day following the last hidden behind the plywood barrier. up weIl across several species and is habituation trial, each lizard in the Results not restricted to the domestic chicken. noise group was individually carried to The visual absence of an E proved the test room and exposed to noise for .to be an effective means of attenuating 1 sec, with the horn held at a distance the immobility reaction. Mean of 8 cm away. The S was then duration of immobility was 834.8 sec REFERENCES immobilized and duration of with the E visible and only 169.8 sec GALLUP, G. G., JR., CREEKMORE. H. S., immobility measured as in when the E was concealed by the & HILL, w. E., III. Shock-enhanced Experiment 1. Noise and no-noise Ss barrier. Using transformed (log 1 0 ) i m rn o b i l i t y reactions in chickens: were tested altemately, and the scores, a between-groups analysis of Support for the fear hvpothesis. The Psvchological Record, 1970, 20. 243-245. procedure for the two groups was variance confirmed a significant GALLUP, G. G., JR., CUMMINGS. W. H., & identical, except.that the horn was not difference between the two testing NASH, R. F. The experimenter as an sounded for Ss in the no-noise group, conditions (F = 7.27, df = 1/10, independent variable in studies of animal Results hvpnosis in chickens (Gallus gallus). p < .025). Anima! Behaviour, 1971, in press. Exposure to a loud noise had an DISCUSSION GALLUP, G. G., JR., NASH, R. F., appreciable effect on the resulting As support for the fear hypothesis, DONEGAN, N. H.. & McCLURE. M. K. duration of immobility. The mean in Experiment 1 the duration of tonic The i m m o b i l i t y response: A predator-induced reaction in chickens. duration of immobility for the noise immobility in the lizard, A. The Psvchological Record, 1971. in press. group was 404.2 sec and only 94.8 sec carolinensis, was found to bear a GALLUP. G. G., JR., NASH. R. F., for the control group. A reliable relationship to the amount of POTTER, R. J., & DONEGAN. N. H. Effect of varving conditions of fear o n transformation (log 1 0 ) was perforrned preinduction shock. These results immobility reactions in domestic on the raw data prior to analysis, and a parallel those where young chickens chickens (Gallus gallus). Journal of between-group analysis of variance given shock prior to manual restraint Comparative & Phvsiological Psy chology, revealed a significant difference remained immobile Ion ger than 1970,73.442-445. GALLUP, G. G., JR., ROSEN, T. S.. & between the two groups (F = 5.02, no-shock controls and the results of BROWN. C. W. Effect of conditioned fear df = 1/18, p < .05). Gallup, Nash, Potter, & Donegan on tonic immobility in domestic EXPERIMENT 3 (1970) where duration of immobility chickens. Journal of Comparative & Working with chickens, Gallup, varied as a function of shock intensity. Physiological Psy ch ologv, 1971, in press. HOAGLAND, H. The mechanism o f tonic Nash, Donegan, & McClure (1971) In the second experiment, lizards immobility ("animal hvpnosis"). Journal found that Ss restrained in the given brief exposure to a loud noise of General Psvchology, 1928a, I, presence of a stuffed Cooper's hawk prior to induction remained immobile 426-447. HOAGLAND. H. On the mechanism of remained immobile co nsiderably over four times longer than controls. tonic immobility in vertebrates. Journal Ionger than controls. Similarly, Gallup, The data from Experiment 2 are of General Psych ology , 1928b. 11. Cummings, & Nash (1971) showed comparable to the finding (Gallup, 715-741. NASH, R. F .. GALLUP, G. G., JR.. & that chickens restrained in the Nash, Potter, & Donegan, 1970) that McCLURE, M. K. The immobility presence of an E remained immobile loud noise, as a method of producing reaction in leopard Irogs (Rana pipiensv longer than those visually separated fear, increased the duration of tonic as a function of noise-induced fear. immobility in chickens. These results Psvchonornic Science, 1970, 21, 155-156. from the E by a plywood barrier. PRESTRUDE, A. M., & CRAWFORD, F. T. These findings fit in weIl with Ratner's also correspond to those of Nash, Tonic immobility in the liz ard, lguana (1967) suggestion that immobility Gallup, & McClure (1970) where frogs iguana. Animal Behaviour, 1970, 18, reactions might have survival value (Rana pipiens) presented with a loud 391-395. RATNER, S. C. Cornparative aspects of under natural conditions and could noise prior to restraint remained h ypnosis. In J. E. Gordon (Ed.), have evolved in response to selective immobile longer than no-noise Handbook ot clinicaI and experimental pressure exerted by predation. In line controls. hypnosis. New Yozk: Macmillan, 1967. Pp. 550-587. with this interpretation 0 f animal The finding of approximately an RATNER, S. C., & THOMPSON, R. W. hypnosis as aresponse to predation, it 80% reduction in the duration of Immobility reactions (fear) of domestic was hypothesized that the duration of immobility in lizards when the E was fowl as a function of age and prior tonic immobility in A. carolinensis concealed behind a barrier is likewise experience. Animal Behaviour, 1960, 8. 186-191. would be increased by the visual analogous to results obtained with SALZEN, E. A. Imprtnttng and the presence of an E and decreased when chickens and supports the notion immobility reactions of domestic fowl. the E was concealed behind a barrier. (Gallup, Curnmings, & Nash, 1971) Anima! Behaviour, 1963, 11, 66-71.

28 Psychon. Sei., 1972, Vol. 26 (l)