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Mood: Experimental analysis in a laboratory setting
.J.psychiat. Res., 1972,
Vol. 9,pp.81-86. Pergamon Press. Printedin GreatBritain.
MOOD: EXPERIMENTAL ANALYSIS IN A LABORATORY SETTING ROBERT P. LIBERMAN* and DAVID E. RASKIN Saint Elizabeth’s Hospital, National Institute of Mental Health, Washington, D.C. 20032 (Received 13 Janllary 1971) (Revised 20 August-1971)
USING techniques developed by operant conditioning, researchers have recently begun to make a scientS?c, experimental analysis of emotional behavior in humans. The key points in an experimental analysis of behavior are: (1) objective description and observation of the focal behavior, (2) reliable recording of changes in rate of the behavior, and (3) a functional analysis of the environmental events which affect the frequency of the behavior. KELLER and SCHOENFELD~ suggested that “The complete removal of secondary positive reinforcers occasions a widespread behavioral depression which involves changes commonly referred to as those of grief, sadness, or sorrow . . . (and) the presentation of reinforcing stimuli should facilitate those responses we call joyful.” FERSTER* views depression as a reduced frequency of motor and verbal behavior. LEWNSOHN et aL3 have experimentally altered clinical depressions by manipulating the contingencies of reinforcement bearing on the depressed individual. Reinforcement of adaptive behaviors and extinction of depressed behaviors (apathy, statements of hopelessness and despair, and somatic complaints) leads to an amelioration of the depression. We performed two laboratory experiments to assess the relative contributions of overt, motor behavior and contingencies of reinforcement to the self-description of mood in human subjects. We were interested in clarifying whether the sadness-happiness dimension of mood is more a function of the level of motor behavior or the receipt of reinforcement. METHOD
In the first experiment, 23 volunteers were drawn from colleges (N = 16), the state employment office (N = 4) and hospitalized alcoholics (N = 3). Their ages ranged from 19 to 42 and 14 were male. They were asked to make instrumental button-pressing responses to acquire money. The subjects, seated at a console in a soundproof room, were instructed to press the button in such a way as to maximize their gain or minimize their loss, depending upon the phase of the experiment. * Present address: Center for the Study of Behavioral Disorders, Camarillo State Hospital, California Department of Mental Hygiene, Camarillo, California 93010. 81
82
ROBERTP. LIBERMAN and DAVID E. RASKIN
The subjects were told that they were going to participate in an experiment which would test their problem-solving ability. They would have to figure out the best and most efficient way of pressing the button to accumulate money. “Your job is to gain as many points as possible. There will be four phases to the experiment and you will have to figure out the way to keep as many points as possible on the scoreboard during each phase. At the end of the experiment, we will give you one cent for each point you have earned. We will talk with you over the intercom at the end of each phase. We want you to answer our questions, which have to do with how you are feeling, as honestly and completely as you can. Your answers to our questions will not affect your earnings.” Each button-press activated a microswitch and various schedules of reinforcement were programmed to give feedback to the subject on a money scoreboard. The experimental apparatus is pictured in Fig. 1 and is described more fully elsewhere.4 The first experiment was divided into four phases, scheduled in the following manner: (1) button-pressing was reinforced on a fixed ratio 4 (FR 4) schedule (i.e., every four buttonpresses added 3 of a cent to the subject’s earnings on the scoreboard); (2) the FR4 schedule continued but a non-contingent, ‘clock cost’ condition was added which consisted of the subtraction of one cent every 2 set irrespective of button-pressing; (3) the FR 4 schedule alone was reinstated; and (4) an extinction period (no reinforcement or cost) was introduced. In the first phase, the subject was permitted to earn about $9.90; the second phase was terminated when the subject had $0.75 of his earnings left. In the third phase, the subject was permitted to regain a $9.90 total; finally, in the extinction phase, the subject merely maintained his $9.90 total since he could neither gain or lose money. A second experiment was conducted to evaluate the changes in mood when amount of reinforcement was kept constant and rate of motor responding was systematically varied. Nine subjects (all college student volunteers) participated under the same conditions and instructions as those provided in the first experiment. After collecting baseline responses to the mood checklist, each subject was exposed to the following schedules of reinforcement: (1) FR 4; (2) DRL 5 set (unlimited hold)-the subject had to space two successive responses by at least 5 set in order to be reinforced: (3) FR 8 ; and (5) extinction. The amount of money given for each reinforcement was manipulated so that by working for about 30 min on each schedule, the subject was able to earn approximately $3.30 per schedule, ending with a total of approximately $9.90. After each button-pressing phase which took an average of 30 min, the subjects were asked to report their mood using unstructured and structured interviews and questionnaries. A checklist was used which consisted of adjectives describing the affects of depression (6 items), feeling carefree (6 items), anxiety (4 items), and hostility (4 items). The checklist was adapted from an NIMH mood scale5 which is being used in a multi-hospital, collaborative study of anti-depressant medications. The subjects read each adjective aloud and then moved a dial on a four point scale to indicate how much of that feeling they were experiencing at that moment. The dependent variable of mood was operationally defined as the difference between the total scores on the carefree and depression items. Higher difference scores mean more carefree feelings relative to depressive feelings. Communication was maintained between the experimenter and the subject by means of one-way closed circuit TV-the experimenter could monitor the subject continuously while the subject could only
MOOD:EXPERIMENTAL
ANALYSISINA
SETTING
LABORATORY
83
receive instructions verbally from the experimenter. We recognized the possible intrusion of the experimenter’s differential reinforcement for certain types of self-report by the subjects and attempted to control this by standardizing our interview format.
RESULTS
Results from the first experiment, portrayed in Fig. 2, showed fairly consistent rates of high responding during the first three phases of the experiment with rapid response cessation during phase 4. The average rates of button-pressing for the first three phases were 236, 183, and 273 responses/mm These rates are consistent with previously reported research using money to reinforce patients and normal subjects.6 FR 4
IXTINCTION
8990 MONEY f?EINF(XKEMENT (CUMULATIVE)
l?UTTW
PRESSES
i-L
-ll
FIG. 2. The relationship
FR 4
T
n
EXTI WTIGN
between amount of reinforcement and mood holding rate of button-pressing constant (N = 23).
Despite the lack of significant differences in the rates of motor behavior, the subjects reported marked changes in their moods during the various phases. Their moods changed as a function of changes in money reinforcement. The subjects reported pleasurable affect during the GAIN phases (1 and 3) and dysphoria during the LOSS phase (2), (carefree minus depression scores of individuals: P < O*OOlphases 1 vs. 2; P < 0.01 phases 2 vs. 3: sign test). The LOSS phase was designed as an experience of relative hopelessness and helplessness for the subject, and thus duplicates some of the dynamics of depression described by clinicians.7-g. The subject can reduce the speed of his loss by pressing the button, but sustains the loss nonetheless. Feelings of confusion and helplessness as well as sadness and unhappiness were forthcoming after this phase of the experiment. The extinction phase (4) produced variable reports of moods, but they generally fell between the GAIN and LOSS moods. When correct for regression, the findings for the extinction phase were
84
ROBERTP. LIBERMAN and DAVIDE. RASKIN
unchanged. There were no differences on the anxiety and hostility scales across the various phases of the experiment. The data from the second experiment are presented in Fig. 3. No significant change in mood across the different schedules occurred even with a marked slowing of response rate on the button-pressing task during the DRL 5 schedule. In both experiments, there was no significant difference in the response rates or mood reports between the hospitalized alcoholics and the normal volunteers. Neither did other variables such as age, sex and social class correlate with the findings.
MO$D CAREkREE MINUS
-6
FIG. 3. The relationship between button-pressing and mood holding amount of reinforcement constant (N = 9). DISCUSSION
The data presented underscore the importance of amount of reinforcement rather than behavioral outputper se as a determinant of mood. The change to dysphoria during phase 2 of the first experiment was more related to reinforcement loss than it was to changes in response rates. The second experiment showed that despite wide variation in motor behavior, mood remained relatively constant as a function of the constancy of reinforcement. There did not appear to be any interaction between the time order of the experimental interventions and the mood reports since the latter showed no consistent fluctuation with the passage of time in the two experiments. These findings qualify FERSTJZR’Shypothetical contention that depression can be equated to a drop in rates of behavior. A clinical implication of this finding is that it is not sufficient to get depressed patients going through the motions of working or being active but crucial to make sure that they receive reinforcement (e.g. recognition, money, approval) for their efforts. It is of interest to note that in a statistical study, GRINKER et al. lo found that overt behavior did not correlate with the feelings or psychological
content of 120 depressed patients.
MOOD : EXPERIMENTAL ANALYSIS IN A LABORATORYSETTING
85
We would speculate that directly reinforcing verbal statements indicative of ‘good mood or ‘elation’ would have an effect on the subject’s mood which would be proportional to the amount of reinforcement provided and relatively independent of the quantity of ‘good mood’ statements. Statements which semantically reflect elation often are emitted in the absence of concordant, affective information: we colloquially refer to individuals who frequently exhibit such semantic/connotative discordance as being ‘phony’ or ‘empty’. A possible explanation for this discordance may he in a history of low reinforcement (i.e. interpersonal acknowledgement) for ‘good mood’ statements which leads first to an extinction of the affective component of the statements before the semantic component. An additional experiment might have been run to assess the impact on mood of reinforcement not contingent upon behavior. If our hypothesis is sound, a group provided with non-contingent reinforcement should experience a rise in mood. Some evidence for this comes from the data during the extinction periods. Despite low rates of behavior, subjects conserved their amount of money and hence were in effect receiving noncontingent reinforcement. Their mood reports generally were high. The inter-subject variability during this phase may reflect the interpretation made by some subjects that maintenance of money earned was an overall gain while others may have interpreted this as a relative loss (deceleration) in their earnings. Each subject was asked about their impi-essions and attitudes of the ‘demand’ characteristics of the experiment prior to leaving the laboratory. Almost all subjects felt they were involved in a study of their ability to solve machine-generated problems. They viewed the mood reports as incidental to the problem-solving nature of the experiment. Three subjects stated that they viewed the experiment as ‘rigged’ with pre-determined outcomes but they were not aware of the interest of the experimenters on the relation between earnings and mood. The implications of our findings for clinical depression must be qualified by the fact that our subjects were not depressed in the clinical sense but rather were exhibiting transient changes in the state of their mood. Thus our experiments are suggestive but far from conclusive in resolving the functional relation between depressive affect and overt behavior vs. density of reinforcement. Our study represents an effort to bring an experimental analysis to bear on an area of human behavior which is difficult to objectify-self-reporting of mood. The clinical problem of depression is formulated by us in behavioral terms more extensively in another publicati0n.l’ We agree with SKINNER~~ that “ . . . a verbal report is a response of the organism; it is part of the behavior which a science must analyse. The analysis must include an independent treatment of events of which the report is a function. The report itself is only half the story.”
SUMMARY
Thirty-two hospitalized alcoholic and normal volunteer subjects reported their mood while working on an instrumental, button-pressing task under different schedules of reinforcement. Mood reliably changed as a function of the amount of money reinforcement,
86
ROBERTP. LIBERMANand DAVID E. RASKIN
independently of variations in response rates. The findings point to the importance amount of reinforcement for altering mood rather than overt behavioral output. Acknowledgement-We thank Dr. Harold which was conducted in his laboratory.
Weiner for his support
and supervision
of
of this research
REFERENCES 1. KELLER, F. S. and SCHOENFELD,W. N. Principles of Psychology, p. 345. Appleton-Century-Crafts, New York, 1950. 2. FERSTER,C. B. Animal behavior and mental illness. Psycho/. Record. 16, 345, 1966. 3. LEWINSOHN,P. M.; WEINSTEIN,M. S. and SHAW, D. Depression: A clinical research approach, in: Advances in Behavior Therapy: 1968, RUBIN, R. and FRANKS, C. (Eds.), p. 231. Academic Press, New York, 1968. 4. WEINER, H. Controlling human fixed-interval performance. J. exptl. anal. Behav. 12, 349, 1969. J., REATIG, N. and MCKEON, J. J. Replication of factors of psycho5. RAXIN, A., SCHUTERBRANDT, pathology in interview, ward behavior, and self-report ratings of hospitalized depressives. J. nerv. mental dis. 148, 87, 1969. 6. SLOANE, R. B., STAPLES,F. R. and PAYNE, R. W. Response to social and monetary reward in neurosis. J. psychiat. Res. 7, 227, 1970. BECK, A. T. Depression. Harper & Row, New York, 1967. :: BIBRING. E. The mechanism of depression, in: Affective Disorders, FREENACRE,P. (Ed.). Internanatiodal Univ. Press, New York, 1953. 9. BOWLBY,J. Grief-and mourning in early childhood. Psychoanal. Study of the Child 15, 9, 1960. 10. GRINKER. R. R.. MILLER, J., SABSHIN,M., NUNN, R. and NUNNALLY,J. The Phenomena of Depression. Hoeber, .New Yo&l961. 11. LIBERMAN,R. P. and RASKIN, D. E. Depression: A behavioral formulation. Archs gen. Psychiat. 24, 515, 1971. 12. SKINNER, B. F. Science and Human Behavior, p. 280. Free Press, New York, 1953.
Vol. 9,pp.81-86. Pergamon Press. Printedin GreatBritain.
MOOD: EXPERIMENTAL ANALYSIS IN A LABORATORY SETTING ROBERT P. LIBERMAN* and DAVID E. RASKIN Saint Elizabeth’s Hospital, National Institute of Mental Health, Washington, D.C. 20032 (Received 13 Janllary 1971) (Revised 20 August-1971)
USING techniques developed by operant conditioning, researchers have recently begun to make a scientS?c, experimental analysis of emotional behavior in humans. The key points in an experimental analysis of behavior are: (1) objective description and observation of the focal behavior, (2) reliable recording of changes in rate of the behavior, and (3) a functional analysis of the environmental events which affect the frequency of the behavior. KELLER and SCHOENFELD~ suggested that “The complete removal of secondary positive reinforcers occasions a widespread behavioral depression which involves changes commonly referred to as those of grief, sadness, or sorrow . . . (and) the presentation of reinforcing stimuli should facilitate those responses we call joyful.” FERSTER* views depression as a reduced frequency of motor and verbal behavior. LEWNSOHN et aL3 have experimentally altered clinical depressions by manipulating the contingencies of reinforcement bearing on the depressed individual. Reinforcement of adaptive behaviors and extinction of depressed behaviors (apathy, statements of hopelessness and despair, and somatic complaints) leads to an amelioration of the depression. We performed two laboratory experiments to assess the relative contributions of overt, motor behavior and contingencies of reinforcement to the self-description of mood in human subjects. We were interested in clarifying whether the sadness-happiness dimension of mood is more a function of the level of motor behavior or the receipt of reinforcement. METHOD
In the first experiment, 23 volunteers were drawn from colleges (N = 16), the state employment office (N = 4) and hospitalized alcoholics (N = 3). Their ages ranged from 19 to 42 and 14 were male. They were asked to make instrumental button-pressing responses to acquire money. The subjects, seated at a console in a soundproof room, were instructed to press the button in such a way as to maximize their gain or minimize their loss, depending upon the phase of the experiment. * Present address: Center for the Study of Behavioral Disorders, Camarillo State Hospital, California Department of Mental Hygiene, Camarillo, California 93010. 81
82
ROBERTP. LIBERMAN and DAVID E. RASKIN
The subjects were told that they were going to participate in an experiment which would test their problem-solving ability. They would have to figure out the best and most efficient way of pressing the button to accumulate money. “Your job is to gain as many points as possible. There will be four phases to the experiment and you will have to figure out the way to keep as many points as possible on the scoreboard during each phase. At the end of the experiment, we will give you one cent for each point you have earned. We will talk with you over the intercom at the end of each phase. We want you to answer our questions, which have to do with how you are feeling, as honestly and completely as you can. Your answers to our questions will not affect your earnings.” Each button-press activated a microswitch and various schedules of reinforcement were programmed to give feedback to the subject on a money scoreboard. The experimental apparatus is pictured in Fig. 1 and is described more fully elsewhere.4 The first experiment was divided into four phases, scheduled in the following manner: (1) button-pressing was reinforced on a fixed ratio 4 (FR 4) schedule (i.e., every four buttonpresses added 3 of a cent to the subject’s earnings on the scoreboard); (2) the FR4 schedule continued but a non-contingent, ‘clock cost’ condition was added which consisted of the subtraction of one cent every 2 set irrespective of button-pressing; (3) the FR 4 schedule alone was reinstated; and (4) an extinction period (no reinforcement or cost) was introduced. In the first phase, the subject was permitted to earn about $9.90; the second phase was terminated when the subject had $0.75 of his earnings left. In the third phase, the subject was permitted to regain a $9.90 total; finally, in the extinction phase, the subject merely maintained his $9.90 total since he could neither gain or lose money. A second experiment was conducted to evaluate the changes in mood when amount of reinforcement was kept constant and rate of motor responding was systematically varied. Nine subjects (all college student volunteers) participated under the same conditions and instructions as those provided in the first experiment. After collecting baseline responses to the mood checklist, each subject was exposed to the following schedules of reinforcement: (1) FR 4; (2) DRL 5 set (unlimited hold)-the subject had to space two successive responses by at least 5 set in order to be reinforced: (3) FR 8 ; and (5) extinction. The amount of money given for each reinforcement was manipulated so that by working for about 30 min on each schedule, the subject was able to earn approximately $3.30 per schedule, ending with a total of approximately $9.90. After each button-pressing phase which took an average of 30 min, the subjects were asked to report their mood using unstructured and structured interviews and questionnaries. A checklist was used which consisted of adjectives describing the affects of depression (6 items), feeling carefree (6 items), anxiety (4 items), and hostility (4 items). The checklist was adapted from an NIMH mood scale5 which is being used in a multi-hospital, collaborative study of anti-depressant medications. The subjects read each adjective aloud and then moved a dial on a four point scale to indicate how much of that feeling they were experiencing at that moment. The dependent variable of mood was operationally defined as the difference between the total scores on the carefree and depression items. Higher difference scores mean more carefree feelings relative to depressive feelings. Communication was maintained between the experimenter and the subject by means of one-way closed circuit TV-the experimenter could monitor the subject continuously while the subject could only
MOOD:EXPERIMENTAL
ANALYSISINA
SETTING
LABORATORY
83
receive instructions verbally from the experimenter. We recognized the possible intrusion of the experimenter’s differential reinforcement for certain types of self-report by the subjects and attempted to control this by standardizing our interview format.
RESULTS
Results from the first experiment, portrayed in Fig. 2, showed fairly consistent rates of high responding during the first three phases of the experiment with rapid response cessation during phase 4. The average rates of button-pressing for the first three phases were 236, 183, and 273 responses/mm These rates are consistent with previously reported research using money to reinforce patients and normal subjects.6 FR 4
IXTINCTION
8990 MONEY f?EINF(XKEMENT (CUMULATIVE)
l?UTTW
PRESSES
i-L
-ll
FIG. 2. The relationship
FR 4
T
n
EXTI WTIGN
between amount of reinforcement and mood holding rate of button-pressing constant (N = 23).
Despite the lack of significant differences in the rates of motor behavior, the subjects reported marked changes in their moods during the various phases. Their moods changed as a function of changes in money reinforcement. The subjects reported pleasurable affect during the GAIN phases (1 and 3) and dysphoria during the LOSS phase (2), (carefree minus depression scores of individuals: P < O*OOlphases 1 vs. 2; P < 0.01 phases 2 vs. 3: sign test). The LOSS phase was designed as an experience of relative hopelessness and helplessness for the subject, and thus duplicates some of the dynamics of depression described by clinicians.7-g. The subject can reduce the speed of his loss by pressing the button, but sustains the loss nonetheless. Feelings of confusion and helplessness as well as sadness and unhappiness were forthcoming after this phase of the experiment. The extinction phase (4) produced variable reports of moods, but they generally fell between the GAIN and LOSS moods. When correct for regression, the findings for the extinction phase were
84
ROBERTP. LIBERMAN and DAVIDE. RASKIN
unchanged. There were no differences on the anxiety and hostility scales across the various phases of the experiment. The data from the second experiment are presented in Fig. 3. No significant change in mood across the different schedules occurred even with a marked slowing of response rate on the button-pressing task during the DRL 5 schedule. In both experiments, there was no significant difference in the response rates or mood reports between the hospitalized alcoholics and the normal volunteers. Neither did other variables such as age, sex and social class correlate with the findings.
MO$D CAREkREE MINUS
-6
FIG. 3. The relationship between button-pressing and mood holding amount of reinforcement constant (N = 9). DISCUSSION
The data presented underscore the importance of amount of reinforcement rather than behavioral outputper se as a determinant of mood. The change to dysphoria during phase 2 of the first experiment was more related to reinforcement loss than it was to changes in response rates. The second experiment showed that despite wide variation in motor behavior, mood remained relatively constant as a function of the constancy of reinforcement. There did not appear to be any interaction between the time order of the experimental interventions and the mood reports since the latter showed no consistent fluctuation with the passage of time in the two experiments. These findings qualify FERSTJZR’Shypothetical contention that depression can be equated to a drop in rates of behavior. A clinical implication of this finding is that it is not sufficient to get depressed patients going through the motions of working or being active but crucial to make sure that they receive reinforcement (e.g. recognition, money, approval) for their efforts. It is of interest to note that in a statistical study, GRINKER et al. lo found that overt behavior did not correlate with the feelings or psychological
content of 120 depressed patients.
MOOD : EXPERIMENTAL ANALYSIS IN A LABORATORYSETTING
85
We would speculate that directly reinforcing verbal statements indicative of ‘good mood or ‘elation’ would have an effect on the subject’s mood which would be proportional to the amount of reinforcement provided and relatively independent of the quantity of ‘good mood’ statements. Statements which semantically reflect elation often are emitted in the absence of concordant, affective information: we colloquially refer to individuals who frequently exhibit such semantic/connotative discordance as being ‘phony’ or ‘empty’. A possible explanation for this discordance may he in a history of low reinforcement (i.e. interpersonal acknowledgement) for ‘good mood’ statements which leads first to an extinction of the affective component of the statements before the semantic component. An additional experiment might have been run to assess the impact on mood of reinforcement not contingent upon behavior. If our hypothesis is sound, a group provided with non-contingent reinforcement should experience a rise in mood. Some evidence for this comes from the data during the extinction periods. Despite low rates of behavior, subjects conserved their amount of money and hence were in effect receiving noncontingent reinforcement. Their mood reports generally were high. The inter-subject variability during this phase may reflect the interpretation made by some subjects that maintenance of money earned was an overall gain while others may have interpreted this as a relative loss (deceleration) in their earnings. Each subject was asked about their impi-essions and attitudes of the ‘demand’ characteristics of the experiment prior to leaving the laboratory. Almost all subjects felt they were involved in a study of their ability to solve machine-generated problems. They viewed the mood reports as incidental to the problem-solving nature of the experiment. Three subjects stated that they viewed the experiment as ‘rigged’ with pre-determined outcomes but they were not aware of the interest of the experimenters on the relation between earnings and mood. The implications of our findings for clinical depression must be qualified by the fact that our subjects were not depressed in the clinical sense but rather were exhibiting transient changes in the state of their mood. Thus our experiments are suggestive but far from conclusive in resolving the functional relation between depressive affect and overt behavior vs. density of reinforcement. Our study represents an effort to bring an experimental analysis to bear on an area of human behavior which is difficult to objectify-self-reporting of mood. The clinical problem of depression is formulated by us in behavioral terms more extensively in another publicati0n.l’ We agree with SKINNER~~ that “ . . . a verbal report is a response of the organism; it is part of the behavior which a science must analyse. The analysis must include an independent treatment of events of which the report is a function. The report itself is only half the story.”
SUMMARY
Thirty-two hospitalized alcoholic and normal volunteer subjects reported their mood while working on an instrumental, button-pressing task under different schedules of reinforcement. Mood reliably changed as a function of the amount of money reinforcement,
86
ROBERTP. LIBERMANand DAVID E. RASKIN
independently of variations in response rates. The findings point to the importance amount of reinforcement for altering mood rather than overt behavioral output. Acknowledgement-We thank Dr. Harold which was conducted in his laboratory.
Weiner for his support
and supervision
of
of this research
REFERENCES 1. KELLER, F. S. and SCHOENFELD,W. N. Principles of Psychology, p. 345. Appleton-Century-Crafts, New York, 1950. 2. FERSTER,C. B. Animal behavior and mental illness. Psycho/. Record. 16, 345, 1966. 3. LEWINSOHN,P. M.; WEINSTEIN,M. S. and SHAW, D. Depression: A clinical research approach, in: Advances in Behavior Therapy: 1968, RUBIN, R. and FRANKS, C. (Eds.), p. 231. Academic Press, New York, 1968. 4. WEINER, H. Controlling human fixed-interval performance. J. exptl. anal. Behav. 12, 349, 1969. J., REATIG, N. and MCKEON, J. J. Replication of factors of psycho5. RAXIN, A., SCHUTERBRANDT, pathology in interview, ward behavior, and self-report ratings of hospitalized depressives. J. nerv. mental dis. 148, 87, 1969. 6. SLOANE, R. B., STAPLES,F. R. and PAYNE, R. W. Response to social and monetary reward in neurosis. J. psychiat. Res. 7, 227, 1970. BECK, A. T. Depression. Harper & Row, New York, 1967. :: BIBRING. E. The mechanism of depression, in: Affective Disorders, FREENACRE,P. (Ed.). Internanatiodal Univ. Press, New York, 1953. 9. BOWLBY,J. Grief-and mourning in early childhood. Psychoanal. Study of the Child 15, 9, 1960. 10. GRINKER. R. R.. MILLER, J., SABSHIN,M., NUNN, R. and NUNNALLY,J. The Phenomena of Depression. Hoeber, .New Yo&l961. 11. LIBERMAN,R. P. and RASKIN, D. E. Depression: A behavioral formulation. Archs gen. Psychiat. 24, 515, 1971. 12. SKINNER, B. F. Science and Human Behavior, p. 280. Free Press, New York, 1953.