Joumal of Intellectual Disability Research, 1992, 36, 403-414
A preliminary analysis of environmental variables affecting the observed biobehavioural states of individuals with profound handicaps S. B. RICHARDS' & L. STERNBERG^ 'Department of Exceptional Student Education, Florida Atlantic University, B6ca Raton, Florida, and ^College of Education, Iowa State University, Ames, Iowa, USA ABSTRACT. Recently, various researchers have recommended investigation of biobehavioural states as a worthwhile endeavour toward providing a more valid assessment of students with profound handicaps. To date, the research conducted in this area has largely focused on the biobehavioural state variable in isolation. This pilot study was conducted to examine the relationships between environmental variables and biobehavioural state variables. Six students with profound handicaps were selected as subjects and observed during normal daily school routines. The investigators discovered significant relationships between the students' prior state, position, grouping, type of staff cue given, the proximity of the staff and type of activity stimulus provided, and the students' biobehavioural states. A discussion of the results and recommendations for future research are provided.
INTRODUCTION Historically, writers atid researchers bave acktiowledged the difficulties associated with assesstnent of students with profoutid handicaps (Simeonnsoti et al, 1980; Taylor 1988). Whether educators have developed optitnal or even appropriate techniques for use with these students is open to question (Sailorl et al, 1988). Recently, some have suggested investigating assessment of biobehavioural states as a potentially promising avenue (Rainforth, 1982; Sternberg & Richards, 1989). Biobehavioural states
Biobehavioural states have been described as a series of physiological ahd observable behaviour states through which individuals pass (Prechtl, 1974; Rainforth, 1982). Biobehavioural states may be the mechanism by which the infant regulates or mediates the reception of and response to stimulation (Als et al, 1977; Brazelton, 1978). Of importance is the occurrence of a biobehaviouiral state where orienting responses appear, thereby signifying increased awareness and potential to respond to environmental stimuli (Rainforth, 1982). Much of the research concerning biobehavioural states has involved infants (elg. Als et al, 1976; Campos & Brackbill, 1973). Recently, researchers have defined Correspondence: Dr Stephen B. Richards, Department of Exceptional Student Education, Elorida Atlantic University, Boca Raton, Elorida 33483, USA. j
403
404
5. B. Richards and L. Stemberg
these states (Stemberg & Richards, 1989) and reliably observed biobehavioural states in chronologically older individuals with profound handicaps (Guess et al, 1988). While researchers working with infants have attempted to address the effects of increased stimulation and varying stimuli on the biobehavioural states and orienting responses of infants (Brackbill, 1971; Moskowitz & Lohman, 1970), few studies have been conducted to address the effects of environmental stimulation on the biobehavioural states of individuals with profound handicaps. Therefore, the purpose of this pilot study was to examine environmental variables that may affect the occurrence of biobehavioural states in general, and in particular, orienting responses in students with profound handicaps. Environmental variables Landesman-Dwyer & Sackett (1978) worked with an experimental group of eight subjects with profound handicaps and observed positive changes in the subjects' activity levels and sleep-wake patterns. These changes were presumably the result of: (1) increased environmental stimulation through the provision of opportunities to interact with peers and enticing objects/toys; and (2) placing subjects in a sitting versus lying position. Three potential sources of environmental stimulation were identified for the present investigation based on Landesman-Dwyer & Sackett's (1978) study: the subject's physical position; the configuration of the group, if any, in which the subject might be placed; and the stimuli or type of activity provided to elicit the subject's attention. Additionally, the type of cue used by staff working with the subject, the proximity of the closest staff member, and the time of day were also identified as environmental variables. Biobehavioural state variables Based on the writings of Brazelton (1973), Campos & Brackbill (1973), LandesmanDwyer & Sackett (1978), Guess et al (1988), and Stemberg & Richards (1989), seven biobehavioural states were identified and defined for this study. Additionally, the prior state of the subject was identified as a potential source of influence.
METHOD Setting Subjects were selected from a classroom for students with profound handicaps which was located on a regular elementary school campus in Southeast Florida. The classroom had nine students, one certified special education teacher, and three paraprofessionals. The subjects spent the majority of time in this classroom and observations were limited to the classroom.
Biobehavioural states
405
Proximity Student is more than one a m ' s length fron any oth'er person. Students/ alone;
Close: Student is within one arm's length of another contact with that person.
Students/ staff: Student/ staff:
Distant:
In-contact;
Staff is more than two arm's from student,
lengths awav ' '
Staff is within two arm's lengths of student. Staff is physically touching the student;
State Student is sana as students/a lone but a staff neober is present within the group.
SeiEure:
A seizure is occurring within the interval.
Asleep:
Student's eyes are closed but rapid eye movements nay be present; there may be some j erky movements; thers may be some vocalization. Student is not responsive to
Student is within two axm's lengths from staff and is primary focus of staff's attention.
stimuli Hone; Gustatory/ olfactoryt Auditory/ generalI
Auditory/ specific;
nodding off or fighting sleep. some vocalization.
Ho specitio stimulus activity is available to the student. Ho/ orienting: Stimulus activity is primarily directed toward eating, tasting, or smelling. A listening activity is audible in the environment (e.g. a radio, record or tape player). A listening activity is within one foot of ths student's head (e.g.' & music box, radio).
Vlsu&i/notox:
The activity prinarily requires the student to look and make a motor response (e.g. playing with a toy).
Tactile:
The activity is prinarily designed to stimulate skin responses (e.g. rubbing on lotion, hot-cold differentiation).
Kinesthetic:
The activity is primarily motion oriented (e.g. swinging, balance ball).
Combination:
Any combination of the above etinulus activities or any activity that emphasises multiple stimuli (e.g. a toy that is pushed and makes noise).
Note;
A stimulus level is scored if it is available to the student, even though the student may not be actively participating or interacting with the stimulus in any obvious fashion.
Sitting;
student is sitting in a chair, in staff's lap, or in any type cf sitting position (e.g. long sitting, oircle sitting, being carried in a sitting position).
Standing:
Student is weight bearing on legs including standing tables and other adaptive equipment.
SupineI
Student is lying on back.
Ptone;
Student is lying on stomach and chest.
Side-lying:
Student is lying on side.
Changing:
Student is displaying more than one of the above positions or walking.
Student's eyes are opened but there is no eye movement. Student's eyes do not appear focused; motor movements appear jerky (e.g. purposeful.
Arousal/ unclear;
Arousal/ orienting;
There may be
Vocalizations may occur.
Student's eyes are opened but are not clearly focused en some environmental stimulus. There may be gross or fine motor movement' but not interactive movements (other than selfstimulatory) with any object or other pekrson in ths environment. There may ; be vocalization. There is no visual or auditory tracking. There is no orienting to clear environnental stimuli. i student's syes are opened and focused on sone environmental stimulus. T'here may be fine and gross motor movements particularly of an interactive nature. There may be visual or auditory tracking. Changes in facial expressions and vocalizations (not of an agitated nature) in response to environnehtBl stimuli will be scored. :
physically directing student. Verbal!
Staff is talking to student.
Touch:
Staff is physically directing student to make a response. Staff is making both physical cues.
and verbal
Figure 1. Environmental variables. Subjects
\
Seven of the nine students were selected to participate in the study. Two students were excluded due to known severe visual impairments which made gathering reliable data extremely difficult because of the need to observe the subject's eye focus and movements (see Biobehavioural State definitions). All subjects were
406
5. B. Richards and L. Stemberg
labelled profoundly mentally retarded which in Florida requires a measured intelligence quotient less than five standard deviations below the mean and adaptive behaviour skills below age and cultural expectations (Florida Department of Education, 1988). Their ages ranged from 8 to 20 years. All subjects were unable to eat, toilet, dress or perform other basic self-care skills independently. All were nonambulatory and non-verbal. Instrumentation and observation procedures The variable definitions used in scoring are included in Fig. 1. The instrument used was refined over a period of 3 months of informal observations. Raters were trained through a trial-and-error method by which independent observations were recorded, compared and discussed. This training, as part of the refinement process, also occurred over the same period of months. Data were recorded using an interval recording system. Each interval was 20 s in duration with 15 s assigned for observation and an additional 5s for recording. Raters were cued at the beginning of each interval and at the end of each 5-s period by a 20-s continuous loop tape played on a cassette tape player. Only one subject was observed student Name Student/Alone students/Alone Students/Staff Student/Staff Gustatory/Olfactory Auditory/General Auditory/Specific Visual/Motor Tactile Kinesthetic Combination Sitting Standing Supine Prone Side-Lying Changing None Verbal Touch Combination Distant Close In-Contact Seizure Asleep No Orienting Agitated Arousal/Unclear Arousal/Orienting
Day X X
X
X X X
X
X X
X
X
Figure 2. Assessment instrument, data.
Time
Biobehavioural states |407
during an interval. The instrument used is shown in Fig, 2. The figure represehts a data sheet used for one minute of observation (i.e. three intervals). ] Subjects were randomly selected for the order in which they were observed on each day. Typically, each subject was observed for five min on each day that data were collected. Observation periods on each subject were distributed withfi\{ein the morning and four in the afternoon across 4 days of the week. The times of the observations were representative but not random, and were selected based on raters' schedules and availability. i Occasionally, data from less than 15 intervals (or 5 min of observations) were recorded on a subject due to some disruption which made visual contact with the subject impossible (e.g. the subject being taken out of the room or behirid a changing screen). Data from 889 intervals were actually recorded and entered. Data from one subject was limited due to his death during the course of the study. Data recording and entry procedures
i
Raters recorded all changes in observed variables (environmental and biobehavioural) which occurred within an interval. This was necessary in order to determine whether increases in variable intensity (e.g. student/alone! to student/staff) occurred with similar changes in the state variable (e.g. no orienting to arousal/orienting). Environmental variable intensity refers to the level at which the student is presumed to be receiving the most stimulation (i.e. the level closest to the bottom of those listed for each variable in Fig. 2). Biobehavioural ^tate intensity was viewed in respect to the subject's overall receptivity to stimulation and the likelihood of achieving an orienting response (again, the level closest to the bottom of the biobehavioural state variable list in Fig. 2). The most intense level of a variable that occurred within an interval was entered for statistical analysis. However, only some of the variables could be treated in this respect. They were: group, the combination level under stimuli, the combination level under cue, proximity, state, and prior state. Other variables or levels under a variable did not lend themselves to this interpretation (e.g. visual versus auditory/specific stimulation, side-lying versus supine position). Check marks on the appropriate corresponding line were used to indicate which level of a variable was observed. More than one level might be checked for any of the variables. The variable level checked closest to the bottom of the list was entered for analysis. With the position and stimuli variables, any changes that occurred within an interval resulted in the scoring of combination for stimuli or changing for position for that interval and that level was subsequently entered for analysis. For example, in Fig. 1, the student was initially alone but at some point during the interval a staff mernber approached the student and the student/staff level was checked. An auditory/general stimulus was available and no other stimulus activity was immediately available to the student. The student was initially supine but moved to side-lying, and therefore, the changing level was scored. Initially, no cue was available, but a verbal cue was delivered later. Staff were distant in proximity at first, but later moved to dose
408
5. B. Richards and L. Sternberg
proximity. Fitially, the student was initially not orienting, but etnitted arousal/orienting behaviour prior to the interval's end. Thus, the levels entered for analysis would be: student/staff, auditory/general, changing, verbal, close, and arousal/orienting. While the changing intensities of levels under the above environmental variables are more clear, the changing intensities of the biobehavioural state variables are perhaps less obvious. However, there is a precedent for this type of arrangement (Guess et al, 1988). As is apparent in subsequent sections, these data were not statistically analysed as ordinal, but as nominal level frequency data. Prior state was derived ex post facto from the recorded observations, as it could not be observed concurrently. That is, the subject's prior state was entered as the state occurring in the immediately previous interval. No prior state was recorded for the first interval of each 5-min observation period. Interrater reliability Two raters were used for all observations both during instrument development and the study reported here. Inter-rater reliability (IR) coefficients were calculated by dividing the total number of agreements by the total number of intervals. It should be noted that an agreement was scored only if the raters' recording sheets matched exactly. In other words, if one rater recorded a change in the variable level (and hence two levels were checked) and the other rater checked only one level, a disagreement was scored even if the sheets matched on the one level checked by both raters. Consequently, the criterion for scoring agreements was stringent. The IR coefficients are included in Table 1. Table 1. Inter-rater reliability (IR) data Range Group . Stimuli • Position jCue Proximity State
Agreements
Disagreements
IR
(75-100%) (88-100%) (92-100%) (83-100%) (76-100%) (73-100%)
830 860 878 838 849 772
59 29 11 51 40 117
93% 97% 99% 94% 96% 87%
Statistical analyses and results Given the level and nature of the data, chi-square analyses were used to test the hypotheses of no relationships between any of the environmental variables or prior state and the state variable. These statistics were calculated using a crosstabulation procedure (each environmental variable and prior state being crosstabulated with the state variable). Contingency coefficients were also calculated to indicate the strength of any significant relationships. The contingency coefficient, which ranges from 0 to 1-0, may be interpreted similarly to a correlation coefficient (Bruning & Kintz, 1987). These data are presented in Table 2.
Biobehavioural states
409
Table 2. Bivariate contingency ceofFicients and significance of chi-square statistics G r
S
P
t
0
0
i m u
s i
1
i
u P
i
C u e
0
p r i
X
0
r s
0
i m i
n
t
a
t
P r
y
t t
e
State
*P
A preliminary analysis of environmental variables affecting the observed biobehavioural states of individuals with profound handicaps S. B. RICHARDS' & L. STERNBERG^ 'Department of Exceptional Student Education, Florida Atlantic University, B6ca Raton, Florida, and ^College of Education, Iowa State University, Ames, Iowa, USA ABSTRACT. Recently, various researchers have recommended investigation of biobehavioural states as a worthwhile endeavour toward providing a more valid assessment of students with profound handicaps. To date, the research conducted in this area has largely focused on the biobehavioural state variable in isolation. This pilot study was conducted to examine the relationships between environmental variables and biobehavioural state variables. Six students with profound handicaps were selected as subjects and observed during normal daily school routines. The investigators discovered significant relationships between the students' prior state, position, grouping, type of staff cue given, the proximity of the staff and type of activity stimulus provided, and the students' biobehavioural states. A discussion of the results and recommendations for future research are provided.
INTRODUCTION Historically, writers atid researchers bave acktiowledged the difficulties associated with assesstnent of students with profoutid handicaps (Simeonnsoti et al, 1980; Taylor 1988). Whether educators have developed optitnal or even appropriate techniques for use with these students is open to question (Sailorl et al, 1988). Recently, some have suggested investigating assessment of biobehavioural states as a potentially promising avenue (Rainforth, 1982; Sternberg & Richards, 1989). Biobehavioural states
Biobehavioural states have been described as a series of physiological ahd observable behaviour states through which individuals pass (Prechtl, 1974; Rainforth, 1982). Biobehavioural states may be the mechanism by which the infant regulates or mediates the reception of and response to stimulation (Als et al, 1977; Brazelton, 1978). Of importance is the occurrence of a biobehaviouiral state where orienting responses appear, thereby signifying increased awareness and potential to respond to environmental stimuli (Rainforth, 1982). Much of the research concerning biobehavioural states has involved infants (elg. Als et al, 1976; Campos & Brackbill, 1973). Recently, researchers have defined Correspondence: Dr Stephen B. Richards, Department of Exceptional Student Education, Elorida Atlantic University, Boca Raton, Elorida 33483, USA. j
403
404
5. B. Richards and L. Stemberg
these states (Stemberg & Richards, 1989) and reliably observed biobehavioural states in chronologically older individuals with profound handicaps (Guess et al, 1988). While researchers working with infants have attempted to address the effects of increased stimulation and varying stimuli on the biobehavioural states and orienting responses of infants (Brackbill, 1971; Moskowitz & Lohman, 1970), few studies have been conducted to address the effects of environmental stimulation on the biobehavioural states of individuals with profound handicaps. Therefore, the purpose of this pilot study was to examine environmental variables that may affect the occurrence of biobehavioural states in general, and in particular, orienting responses in students with profound handicaps. Environmental variables Landesman-Dwyer & Sackett (1978) worked with an experimental group of eight subjects with profound handicaps and observed positive changes in the subjects' activity levels and sleep-wake patterns. These changes were presumably the result of: (1) increased environmental stimulation through the provision of opportunities to interact with peers and enticing objects/toys; and (2) placing subjects in a sitting versus lying position. Three potential sources of environmental stimulation were identified for the present investigation based on Landesman-Dwyer & Sackett's (1978) study: the subject's physical position; the configuration of the group, if any, in which the subject might be placed; and the stimuli or type of activity provided to elicit the subject's attention. Additionally, the type of cue used by staff working with the subject, the proximity of the closest staff member, and the time of day were also identified as environmental variables. Biobehavioural state variables Based on the writings of Brazelton (1973), Campos & Brackbill (1973), LandesmanDwyer & Sackett (1978), Guess et al (1988), and Stemberg & Richards (1989), seven biobehavioural states were identified and defined for this study. Additionally, the prior state of the subject was identified as a potential source of influence.
METHOD Setting Subjects were selected from a classroom for students with profound handicaps which was located on a regular elementary school campus in Southeast Florida. The classroom had nine students, one certified special education teacher, and three paraprofessionals. The subjects spent the majority of time in this classroom and observations were limited to the classroom.
Biobehavioural states
405
Proximity Student is more than one a m ' s length fron any oth'er person. Students/ alone;
Close: Student is within one arm's length of another contact with that person.
Students/ staff: Student/ staff:
Distant:
In-contact;
Staff is more than two arm's from student,
lengths awav ' '
Staff is within two arm's lengths of student. Staff is physically touching the student;
State Student is sana as students/a lone but a staff neober is present within the group.
SeiEure:
A seizure is occurring within the interval.
Asleep:
Student's eyes are closed but rapid eye movements nay be present; there may be some j erky movements; thers may be some vocalization. Student is not responsive to
Student is within two axm's lengths from staff and is primary focus of staff's attention.
stimuli Hone; Gustatory/ olfactoryt Auditory/ generalI
Auditory/ specific;
nodding off or fighting sleep. some vocalization.
Ho specitio stimulus activity is available to the student. Ho/ orienting: Stimulus activity is primarily directed toward eating, tasting, or smelling. A listening activity is audible in the environment (e.g. a radio, record or tape player). A listening activity is within one foot of ths student's head (e.g.' & music box, radio).
Vlsu&i/notox:
The activity prinarily requires the student to look and make a motor response (e.g. playing with a toy).
Tactile:
The activity is prinarily designed to stimulate skin responses (e.g. rubbing on lotion, hot-cold differentiation).
Kinesthetic:
The activity is primarily motion oriented (e.g. swinging, balance ball).
Combination:
Any combination of the above etinulus activities or any activity that emphasises multiple stimuli (e.g. a toy that is pushed and makes noise).
Note;
A stimulus level is scored if it is available to the student, even though the student may not be actively participating or interacting with the stimulus in any obvious fashion.
Sitting;
student is sitting in a chair, in staff's lap, or in any type cf sitting position (e.g. long sitting, oircle sitting, being carried in a sitting position).
Standing:
Student is weight bearing on legs including standing tables and other adaptive equipment.
SupineI
Student is lying on back.
Ptone;
Student is lying on stomach and chest.
Side-lying:
Student is lying on side.
Changing:
Student is displaying more than one of the above positions or walking.
Student's eyes are opened but there is no eye movement. Student's eyes do not appear focused; motor movements appear jerky (e.g. purposeful.
Arousal/ unclear;
Arousal/ orienting;
There may be
Vocalizations may occur.
Student's eyes are opened but are not clearly focused en some environmental stimulus. There may be gross or fine motor movement' but not interactive movements (other than selfstimulatory) with any object or other pekrson in ths environment. There may ; be vocalization. There is no visual or auditory tracking. There is no orienting to clear environnental stimuli. i student's syes are opened and focused on sone environmental stimulus. T'here may be fine and gross motor movements particularly of an interactive nature. There may be visual or auditory tracking. Changes in facial expressions and vocalizations (not of an agitated nature) in response to environnehtBl stimuli will be scored. :
physically directing student. Verbal!
Staff is talking to student.
Touch:
Staff is physically directing student to make a response. Staff is making both physical cues.
and verbal
Figure 1. Environmental variables. Subjects
\
Seven of the nine students were selected to participate in the study. Two students were excluded due to known severe visual impairments which made gathering reliable data extremely difficult because of the need to observe the subject's eye focus and movements (see Biobehavioural State definitions). All subjects were
406
5. B. Richards and L. Stemberg
labelled profoundly mentally retarded which in Florida requires a measured intelligence quotient less than five standard deviations below the mean and adaptive behaviour skills below age and cultural expectations (Florida Department of Education, 1988). Their ages ranged from 8 to 20 years. All subjects were unable to eat, toilet, dress or perform other basic self-care skills independently. All were nonambulatory and non-verbal. Instrumentation and observation procedures The variable definitions used in scoring are included in Fig. 1. The instrument used was refined over a period of 3 months of informal observations. Raters were trained through a trial-and-error method by which independent observations were recorded, compared and discussed. This training, as part of the refinement process, also occurred over the same period of months. Data were recorded using an interval recording system. Each interval was 20 s in duration with 15 s assigned for observation and an additional 5s for recording. Raters were cued at the beginning of each interval and at the end of each 5-s period by a 20-s continuous loop tape played on a cassette tape player. Only one subject was observed student Name Student/Alone students/Alone Students/Staff Student/Staff Gustatory/Olfactory Auditory/General Auditory/Specific Visual/Motor Tactile Kinesthetic Combination Sitting Standing Supine Prone Side-Lying Changing None Verbal Touch Combination Distant Close In-Contact Seizure Asleep No Orienting Agitated Arousal/Unclear Arousal/Orienting
Day X X
X
X X X
X
X X
X
X
Figure 2. Assessment instrument, data.
Time
Biobehavioural states |407
during an interval. The instrument used is shown in Fig, 2. The figure represehts a data sheet used for one minute of observation (i.e. three intervals). ] Subjects were randomly selected for the order in which they were observed on each day. Typically, each subject was observed for five min on each day that data were collected. Observation periods on each subject were distributed withfi\{ein the morning and four in the afternoon across 4 days of the week. The times of the observations were representative but not random, and were selected based on raters' schedules and availability. i Occasionally, data from less than 15 intervals (or 5 min of observations) were recorded on a subject due to some disruption which made visual contact with the subject impossible (e.g. the subject being taken out of the room or behirid a changing screen). Data from 889 intervals were actually recorded and entered. Data from one subject was limited due to his death during the course of the study. Data recording and entry procedures
i
Raters recorded all changes in observed variables (environmental and biobehavioural) which occurred within an interval. This was necessary in order to determine whether increases in variable intensity (e.g. student/alone! to student/staff) occurred with similar changes in the state variable (e.g. no orienting to arousal/orienting). Environmental variable intensity refers to the level at which the student is presumed to be receiving the most stimulation (i.e. the level closest to the bottom of those listed for each variable in Fig. 2). Biobehavioural ^tate intensity was viewed in respect to the subject's overall receptivity to stimulation and the likelihood of achieving an orienting response (again, the level closest to the bottom of the biobehavioural state variable list in Fig. 2). The most intense level of a variable that occurred within an interval was entered for statistical analysis. However, only some of the variables could be treated in this respect. They were: group, the combination level under stimuli, the combination level under cue, proximity, state, and prior state. Other variables or levels under a variable did not lend themselves to this interpretation (e.g. visual versus auditory/specific stimulation, side-lying versus supine position). Check marks on the appropriate corresponding line were used to indicate which level of a variable was observed. More than one level might be checked for any of the variables. The variable level checked closest to the bottom of the list was entered for analysis. With the position and stimuli variables, any changes that occurred within an interval resulted in the scoring of combination for stimuli or changing for position for that interval and that level was subsequently entered for analysis. For example, in Fig. 1, the student was initially alone but at some point during the interval a staff mernber approached the student and the student/staff level was checked. An auditory/general stimulus was available and no other stimulus activity was immediately available to the student. The student was initially supine but moved to side-lying, and therefore, the changing level was scored. Initially, no cue was available, but a verbal cue was delivered later. Staff were distant in proximity at first, but later moved to dose
408
5. B. Richards and L. Sternberg
proximity. Fitially, the student was initially not orienting, but etnitted arousal/orienting behaviour prior to the interval's end. Thus, the levels entered for analysis would be: student/staff, auditory/general, changing, verbal, close, and arousal/orienting. While the changing intensities of levels under the above environmental variables are more clear, the changing intensities of the biobehavioural state variables are perhaps less obvious. However, there is a precedent for this type of arrangement (Guess et al, 1988). As is apparent in subsequent sections, these data were not statistically analysed as ordinal, but as nominal level frequency data. Prior state was derived ex post facto from the recorded observations, as it could not be observed concurrently. That is, the subject's prior state was entered as the state occurring in the immediately previous interval. No prior state was recorded for the first interval of each 5-min observation period. Interrater reliability Two raters were used for all observations both during instrument development and the study reported here. Inter-rater reliability (IR) coefficients were calculated by dividing the total number of agreements by the total number of intervals. It should be noted that an agreement was scored only if the raters' recording sheets matched exactly. In other words, if one rater recorded a change in the variable level (and hence two levels were checked) and the other rater checked only one level, a disagreement was scored even if the sheets matched on the one level checked by both raters. Consequently, the criterion for scoring agreements was stringent. The IR coefficients are included in Table 1. Table 1. Inter-rater reliability (IR) data Range Group . Stimuli • Position jCue Proximity State
Agreements
Disagreements
IR
(75-100%) (88-100%) (92-100%) (83-100%) (76-100%) (73-100%)
830 860 878 838 849 772
59 29 11 51 40 117
93% 97% 99% 94% 96% 87%
Statistical analyses and results Given the level and nature of the data, chi-square analyses were used to test the hypotheses of no relationships between any of the environmental variables or prior state and the state variable. These statistics were calculated using a crosstabulation procedure (each environmental variable and prior state being crosstabulated with the state variable). Contingency coefficients were also calculated to indicate the strength of any significant relationships. The contingency coefficient, which ranges from 0 to 1-0, may be interpreted similarly to a correlation coefficient (Bruning & Kintz, 1987). These data are presented in Table 2.
Biobehavioural states
409
Table 2. Bivariate contingency ceofFicients and significance of chi-square statistics G r
S
P
t
0
0
i m u
s i
1
i
u P
i
C u e
0
p r i
X
0
r s
0
i m i
n
t
a
t
P r
y
t t
e
State
*P
