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Television Viewing at Home: Distances and Visual Angles of Children and Adults

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Television viewing distances, visual angles, and viewing angles were calculated for 217 children and 149 adults from 78 families. The data were obtained from time-lapse videotapes automatically recorded in the families' homes over 10-day periods. Viewing distance increases with age, and visual angle decreases with age. Viewers aged 17 years and younger viewed at an average distance of 225.3 em, at an average visual angle of 12.3 deg, and at an average viewing angle of 23.7 deg. Adult viewers watched TV at an average distance of 336.8 cm, an average visual angle of 6.6 deg, and at an average viewing angle of 23.3 deg. The best predictors of viewing location were (1) percentage of time the viewer watched TV from furniture, (2) room area, and (3) screen width.
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DOI: 10.1177/001872088502700410 1985 27: 467Human Factors: The Journal of the Human Factors and Ergonomics Society
John G. Nathan, Daniel R. Anderson, Diane E. Field and Patricia Collins
Television Viewing at Home: Distances and Visual Angles of Children and Adults
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HUMAN FACTORS, 1985,27(4),467-476
Television Viewing at Home: Distances and
Visual Angles of Children and Adults
JOHN G. NATHAN, DANIEL R. ANDERSON,l DIANE E. FIELD, and PATRICIA COLLINS,
University of Massachusetts, Amherst, Massachusetts
Television viewing distances, visual angles, and viewing angles were calculated for 217
children and
149
adults from
78
families. The data were obtained from time-lapse videotapes
automatically recorded in the families' homes over lO-day periods. Viewing distance in-
creases with age, and visual angle decreases with age. Viewers aged
17
years and younger
viewed at an average distance
of
225.3 em, at an average visual angle
of
12.3 deg, and at
an average viewing angle of 23.7 deg. Adult viewers watched TV at an average distance of
336.8 em, an average visual angle
of
6.6 deg, and at an average viewing angle
of
23.3 deg.
The best predictors
of
viewing location were (1) percentage of time the viewer watched TV
from furniture, (2) room area, and (3) screen width.
There is little published research on the
human factors of ordinary home television
viewing despite television's status as the
dominant news and entertainment medium.
Research is desirable given recurrent public
concerns about the physiological and psycho-
logical impact of television and given current
intense interest in extending and redesigning
transmission and receiver technology. In par-
ticular, detailed descriptions of ordinary tele-
vision viewing behavior at home would be of
use in evaluating the medium's impact and
in providing baseline data against which the
use of new technologies can be considered.
The human factors aspect of present con-
cern is the location of viewers relative to the
TV screen. The design of videotext displays,
the use of interactive devices, the develop-
ment of new screen and audio technologies,
I
Requests for reprints should be sent to Daniel R. An-
derson, Department of Psychology. University of Massa-
chusetts, Amherst, MA 01003.
as well as concerns about the effects of radia-
tion, all involve considerations of viewing
distances and angles. There are, however, no
published descriptive data on these aspects
of television use. The present paper provides
the first descriptive analyses of viewer loca-
tion during normal television viewing at
home.
Recommendations for TV viewing location
have been based primarily on perceptual and
health considerations. McVey (1970), for ex-
ample, recommended as optimum a viewing
distance of 6.25 screen widths at a viewing
angle normal to the screen thus sub tending a
visual angle of 9 deg horizontally. The ratio-
nale for this recommendation is based on pe-
ripherally relevant perceptual research:
Enoch (1959) had earlier reported that 9 deg
was the optimal visual angle for presenting
aerial photographs in search tasks. Hochberg
and Brooks (1978), on the other hand, have
argued that such recommendations are sim-
©
1985, The Human Factors Society, Inc. All rights reserved.
by guest on February 26, 2014hfs.sagepub.comDownloaded from
468-August, 1985
plistic because the complex interactions of
distance, visual angle, viewing angle, picture
resolution, and stimulus structure are not
well understood.
Other recommendations of viewing dis-
tances stem from concerns about the physical
effects of television, especially with respect to
radiation emitted by older color receivers.
Estimates of viewers' radiation exposure
have been calculated on the basis of data col-
lected from discussions with Public Health
Service employees from 741 households in
the Washington, D.C., area (National Center
for Radiological Health, 1968). These discus-
sions indicated average viewing distances of
215.1 cm for viewers under 15 years of age
and 298.4 cm for viewers over 15 years. There
were no direct observations of TV viewing be-
havior as a validation of these distance esti-
mates.
As part of a larger study on home television
viewing behavior (Anderson, Field, Collins,
Lorch, and Nathan, in press), the present
work examines actual TV viewing locations
of adults and children. The research is not
theoretically motivated but rather attempts
to establish descriptive empirical informa-
tion on the use of television within the home.
The procedure involved analysis of time-
lapse videotapes of TV viewers automatically
recorded in homes over lO-day periods.
METHOD
Subjects
Seventy-eight families (three nonwhite) from
metropolitan Springfield, Massachusetts,
participated in the research. The families,
each of which had a five-year-old child, con-
sisted of 366 individuals (including family
members and visitors). The family members
ranged in age from less than 1 month to 63
years, and included 135 preschool children
(69 males and 66 females), 60 elementary-
school-aged children (33 males and 27 fe-
HUMAN FACTORS
males, aged 6 through 11 years), 22 adoles-
cents (6 males and 16 females, aged 12 to 17
years), and 149 adults (71 males and 78 fe-
males, aged 18 to 63 years). As measured by
the Hollingshead Four Factor Index of Social
Status (1975), the families ranged from Level
I (major business or professional occupa-
tions) to Level V (unskilled laborers and
menial service workers). Twenty-nine (37.2%)
families were at Level I, 31 (39.7%) at Level
II, 14 (17.9%) at Level III, 3 (3.8%) at Level
IV,
and 1 (1.3%) at Level V. The modal family
was at Level II, represented by medium busi-
ness, minor professional, and technical oc-
cupations.
Families, whose names were obtained from
public birth records, were sent a letter ex-
plaining the study and later were contacted
by telephone. Of those contacted, 12.2% ac-
tually completed the entire two-month pro-
cedure (which included laboratory visits and
other procedures not relevant to the present
paper). These families did not differ system-
atically on analyses of a large variety of de-
mographic and TV viewing variables from
control families who did not receive video-
tape equipment in their homes (Anderson et
al., in press). All families were paid $25 for
participation in the study. Detailed analyses
of the families and selection factors appear in
a paper by Anderson et al. (in press). The
present descriptive analyses of viewer dis-
tance and angles are essentially incidental to
the major purposes of the larger study. As
such, time and expense limitations precluded
testing family member's vision and audition.
Table 1 provides relevant home viewing char-
acteristics.
Apparatus
Each automated time-lapse video recording
unitconsistedofa61.0cm x 66.0cm x 76.2
cm cart with wooden panels which contained
the NEC model VC-750S black and white
time-lapse videocassette deck as well as the
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TV VIEWING DISTANCES
TABLE 1
TV Viewing Characteristics of 78 Families
Average number of televisions: 1.7
Median diagonal screen size of TV most
frequently used (em): 48.3
Average number of rooms: 7.0
Average TV viewing room size (m2)20.5
Average room area from which TV is
viewable (m2)15.8
control circuitry, time-date generator (RCA
Model TC 144GB), screen splitter (TEL SS-
221), and battery backup devices. Connected
to the cart were two video cameras. One
camera (RCA Model TC1005) was equipped
with a zoom lens (KOWA) and was directed at
the family's TV screen. The other camera
(RCA Model TC1025) was equipped with an
8.5-mm wide-angle lens with auto servo iris,
which automatically compensated for
changes in ambient illumination.
Depending on the positioning of the cart in
the TV room, the cameras were mounted ei-
ther on a stand attached to the cart or on a
tripod fixed to a sturdy base. Recording was
initiated by the control circuitry whenever
the TV set was turned on and was terminated
when the set was turned off. Time-lapse re-
cording without audio was at a ratio of 1:36
(one video frame each 1.2 s). Date and time
were superimposed in one corner of the re-
corded image. An insert of the TV screen ap-
peared every 18 s and remained for 6 s. An
external LED signaled the family that the
cassette was to be changed after 26 h of re-
cording. Ten consecutive days of TV viewing
were recorded for each family between March
1980 and December 1981.
Procedure
Two or three installers went to the home of
each participating family. Upon arrival, the
procedure for installing the equipment was
briefly explained to a parent, usually the
mother, who provided information about fa-
August, 1985-469
vorite viewing locations in the room, lighting,
and channel reception. At the end of the visit,
the parent was instructed in the management
of the videotape changes and was given tele-
phone numbers to call at any time in case of
equipment malfunction. Installation time
was from 1.5 to 2 hours per unit.
If more than one TV was regularly used in
the home, and if the family agreed, camera
uni ts were supplied for each room with a tele-
vision (10 families of the present sample had
multiple camera units; analyses will be pre-
sented for the most frequently used TV sets
from these families). In each TV location,
cameras were situated to record the TV
viewing area as well as the TV screen. Of the
area in the room from which a viewer could
see the TV, an average of 60.9% was covered
by the wide-angle lens. This area included the
most likely TV viewing positions. The place-
ment of the cart was unobtrusive but acces-
sible for viewing the signal light and for
changing the videotape. Furniture rearrange-
ment was kept at a minimum to preserve the
family's natural viewing patterns. Finally, di-
mensions of the TV room and its furnishings
were measured, and a map was later drawn
to scale.
The videotapes were subsequently rated by
means of time samples taken every 55 min-
utes of "television on" time over the lO-day
recording period. The tapes were played on a
Sony BVU 200 videocassette deck, which al-
lowed playback at variable rates of speed.
Two raters viewed the tapes on a high-reso-
lution monitor, holding the tape in still frame
mode to record the presence, location, and
visual attention to the TV of each person in
the viewing room. At each 55-minute stop of
the tape, the rater coded on the scale drawing
the location of a person and whether he or
she was visually oriented toward the televi-
sion screen. Analyses of the visual attention
data will be reported in a subsequent paper
(also see Anderson, in press, and Anderson
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470-August, 1985
and Field, 1983). Individuals were included
as subjects only if they were observed a min-
imum of three times in the television viewing
room and could be identified by age in a
viewing diary maintained by the family. The
average number of observations per indi-
vidual for the 10 days was 16.6 and ranged
from 3 to 62.
Working from the coded viewing locations
on the scale drawings, three measures were
computed for each observation of each
viewer. Viewing distance was measured from
the viewer to the center of the television
screen. Visual angle was computed as the
angle sub tended horizontally by the TV
screen with respect to the viewer. Measure-
ments of vertical angles were not obtained,
as they were very difficult to estimate and
only rarely deviated substantially from that
horizontal plane normal to the approximate
plane formed by the screen surface. In addi-
tion, the viewing angle was defined as the
acute angle formed by the line of gaze to the
center of the screen and the line normal to
the center of the screen.
RESULTS
Five dependent variables were derived
from the observations of the viewing loca-
tions: absolute distance, relative distance in
screen widths, percentage of observations in
which the viewer was closer than 91.4 cm to
the screen, visual angle (deg), viewing angle
(deg), and percentage of observations in
which the viewer was sitting or lying on fur-
niture. Analyses considered averages of all
viewing locations of each subject as well as
modal (most typical) viewing location of each
subject. Average and modal values were in
general agreement; modal values are re-
ported here unless otherwise indicated.
Table 2 indicates for each dependent vari-
able the average modal value and standard
deviation as a function of age grouping: pre-
school (zero through 5 years), school-aged (6
HUMAN FACTORS
through 11 years), adolescents (12 through 17
years), and adults (18 through 63 years). Age
Grouping x Sex analyses of variance re-
vealed significant age differences for absolute
distance,
F(3,358)
=
35.7, p
<
0.001; relative
distance,
F(3,358)
=
24.7,
p
<
0.001; and vi-
sual angle,
F(3,358)
=
9.5,
p
<0.001. Al-
though there was no significant age trend of
viewing angle, the proportion of observations
that a viewer was extremely close (91.4 cm
or less) to the
TV
steadily decreased with age,
F(3,358)
=
13.5, p
<
0.001. The tendency to
view TV while sitting or lying on a chair or
couch increased with age so that adults al-
most always viewed TV from furniture,
F(3,358)
=
55.6, p
<
0.001. The only signifi-
cant effect related to sex was that males
viewed slightly closer (257.8 em) than fe-
males (283.2 em),
F(1,358)
=
4.9,
P
<
0.05.
Children are more variable in their viewing
locations than are adults. Table 2 indicates
the average of each subject's standard devia-
tion of viewing distance as a function of age
group: variability in viewing location de-
creases with age,
F(3,358)
=
16.1,
p
<0.001.
These analyses support our qualitative obser-
vation of the videotapes to the effect that, rel-
ative to children, adults view television from
a favorite location, almost always on a given
couch or chair. Children tend to be more ac-
tive in front of the TV, often playing on the
floor, and often moving from place to place
in the room. They are also more likely than
adults to be extremely close to the TV. This
extremely close viewing tended to come from
a few children who typically sat close to the
TV set; 10.1% of children had their modal po-
sition within 91.4 cm, whereas only one adult
typically viewed that close to the TV (he usu-
ally viewed while lying on the floor with his
head right in front of the screen).
Individual differences in viewing locations
are illustrated separately for children and
adults by the cumulative percentage fre-
quency distributions in Figures 1, 2, 3, and 4.
by guest on February 26, 2014hfs.sagepub.comDownloaded from
TV VIEWING DISTANCES
August, 1985-471
TABLE 2
Average Values and (Standard Deviations) for TV Viewing Position as a Function of Age Group
Age Group
Preschool School Age Adolescent Adult
n135 60 22 149
Typical distance (cm) 228.6 220.2 218.4 336.8
(111.5) (91.4) (95.8) (97.5)
Relative typical distance (W) 5.9 5.7 5.6 8.6
(3.3) (2.7) (2.3) (3.0)
Percentage of observations closer than 91.4 cm 11.2 8.9 5.7 1.3
(17.4) (15.6) (15.3) (6.6)
Typical visual angle (deg) 12.3 13.0 10.6 6.6
(12.5) (16.2) (5.0) (2.6)
Typical viewing angle (deg) 24.1 22.1 25.2 23.3
(19.0) (17.8) (15.4) (15.3)
Percentage of observations on furniture 45.6 56.8 65.0 83.6
Average individual distance standard
deviation (cm) 86.4 78.7 59.4 58.9
A single representation of the modal viewing
locations that combines the data in Figures
2, 3, and 4 is shown in the scatter plot of
Figure 5. The origin of the plot represents the
center of the TV screen, and distances from
the center of the screen are represented as
screen widths. Data for children are plotted
in the upper half of the figure and adult data
are plotted in the lower half of the figure (ac-
tual position to the right or left of the screen
was not coded). The dotted lines radiating
from the origin represent viewing angle in 10-
deg increments, and the circles tangential to
the center of the screen indicate regions of
constant visual angle (4, 6, 8, 10,20, and 30
deg). The plot clearly reveals the between-
subjects variability and the relative differ-
ences between child and adult modal viewing
locations.
In a preliminary effort to account for choice
of viewing location, we performed stepwise
multiple linear regression analyses for the
children as a combined group and separately
for adults. Dependent variables were abso-
lute distance, visual angle, and viewing
angle. One set of analyses utilized viewable
room area and characteristics of the TV set
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DISTANCE
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Figure 1. Cumulative percentage distribution of typ-
ical viewing distances in children (squares) and
adults (plus signs).
by guest on February 26, 2014hfs.sagepub.comDownloaded from
472-August, 1985
HUMAN FACTORS
60 00
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20 20
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DISTANCE IN SCREEN WIDTHS
Figure 2.
Cumulative percentage distribution of typ-
ical viewing distances in screen widths for children
(squares) and adults (plus signs).
(screen width, color versus monochrome, and
cable versus broadcast reception). For chil-
dren, distance from the TV was predicted by
viewable room area only, B
=
0.0004,
F(I,21S)
=
7.6,
p
<
om,
R
=
0.18. Visual
angle, on the other hand, was accounted for
by screen width only B
=
0.304, F(1,2IS)
=
6.0,p < 0.05, R
=
0.16; as was viewing angle,
B
=
-0.300, F(I,21S)
=
5.0,
p
< 0.05, R
=
0.15. For adults, distance was predicted by
viewable room area, B
=
0.001, F(1,147)
=
13.7, p< 0.001, R
=
0.29, followed by screen
width, B
=
2.45, F(1,147
=
5.7, p< 0.05, R
=
0.35. Visual angle was best predicted by
screen width, B
=
0.088, F(I,147)
=
10.9,
p
< 0.001, R
=
0.26, followed by viewable room
area,B
=
-0.0002,F(1,147)
=
I2.l,p<0.001,
R
=
0.38. None of the variables significantly
accounted for adult viewing angle. Thus,
viewing location is best accounted for by the
size of the room area from which the TV can
be viewed as well as by screen size. Factors
that may relate to picture quality (color,
cable) have no independent relationship to
viewing location in either children or adults.
5 10
is
20 25 :SO 35 40
VISUAL ANGLE (DEG.)
Figure 3.
Cumulative percentage distribution of typ-
ical visual angles in children (squares) and adults
(plus signs).
A second set of stepwise regression analyses
predicted distance, visual angle, and viewing
angle based on three viewer behavioral char-
acteristics: percentage of visual attention to
the TV, percentage of observations in which
60
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Z
W
'-'
a:
60
w
0-
w
:>
H
f--
<J:
.0
-'
::J
:E:
::J
'-'
20
LO 20 30 40 SO
bO
70 80
VIEWING ANGLE (DEG.)
Figure 4. Cumulative percentage distribution of typ-
ical viewing angles in children (squares) and adults
(plus signs).
by guest on February 26, 2014hfs.sagepub.comDownloaded from
TV VIEWING DISTANCES
August, 1985--473
01STAHCR IN SCRBBN WIDTHS
0.027, F(l,125)
=
7.3,
p<
0.01, R
=
0.45.
None of the variables predicted viewing
angle .
Clearly, the viewer behavior that best ac-
counts for viewing location in both children
and adults is the tendency to view from fur-
niture. People who view TV from furniture
are farther away from the TV and conse-
quently view at a smaller visual angle. Sec-
ondarily, greater attention to the TV predicts
viewing at a larger visual angle. Total time
with television does not account for viewing
location.
A subsequent set of stepwise regression
analyses combined the significant physical
variables (viewable room area and screen
width) as well as the significant behavioral
variables (percentage of time on furniture
and percentage of visual attention). The re-
sults of these analyses show that the best pre-
dictor of distance and visual angle in both
children and adults is the behavioral vari-
able, percentage of time on furniture. Sec-
ondarily, viewable room area and screen
width account for viewing location followed
by
visual attention to the TV.
The generality of the results was assessed
by comparing the present typical distance
data to those reported by the National Center
for Radiological Health
(1968).
A comparison
for viewers under
15
years and over
15
years
is found in Table 3. An estimate of average
viewing distance from their data for the
younger group
(215.1
cm) compares quite fa-
vorably with ours
(226.1
cm). For viewers
over 15 years, their average of
298.4
cm is
reasonably close to our finding of
330.2
cm.
Chi-square analyses of the data in Table 3 in-
dicate that our under-IS-years data has a
slightly flatter distribution than does the
NCRH data, X
2(4)
=
20.1,
p
<
0.05.
There
were no significant differences between the
distributions for adults,
X2
(4)
=
4.1,p
>
0.05.
A major difference between the earlier
study and ours is that our research was based
on actual observation of TV viewing, whereas
.'
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the viewer was on furniture, and the average
number of hours per day the viewer was in
the viewing room. For children, distance was
best predicted by time on furniture,
B
=
1.41, F(I,207)
=
23.0,
p
<0.001, R
=
0.32;
followed by visual attention to the TV,
B
=
-0.83, F(1,207)
=
8.0,
p
<
0.001, R
=
0.37.
Visual angle was similarly predicted by per-
centage of time on furniture,
B
=
-0.136,
F(1,207)
=
12.8,
p
<
0.001, R
=
0.24;
as well
as by visual attention,
B
=
0.0836, F(l,207)
=
4.8,
p
<0.05, R
=
0.28.
Viewing angle was
not predicted by any of the variables. For
adults, distance was predicted only by per-
centage of time on furniture,
B
=
1.95,
F(I,125)
=
19.4, p
<
0.001, R
=
0.37.
Visual
angle was predicted by percentage of time on
furniture,
B
=
-0.060, F(1,125)
=
23.7,
p
<
0.001, R
=
0.40;
and by visual attention,
B
=
Figure 5. Scatter plot of typical viewing locations of
children (upper half of figure) and adults (lower half
of figure). The origin of the plot represents the center
of the TV screen and the axes represent relative dis-
tance in screen widths. The dotted lines indicate
viewing angle in JO-deg increments. The circles tan-
gential to the center of the TV screen indicate regions
of constant visual angle: 4, 6, 8, 10,20, and 30 deg.
by guest on February 26, 2014hfs.sagepub.comDownloaded from
474-August, 1985
TABLE 3
HUMAN FACTORS
Comparison of National Radiological Health Center (1968)* Viewing Distance Relative Frequencies (Per-
centages) with Present Viewing Distance Relative Frequencies**
Distance (m)
Age
<15
years
Age
>15
years
• Distances were reported in feet
.•• Present data in parentheses
<1.2
9.2
(15.8)
2.1
(1.3)
1.2-2.1
53.5
(38.3)
21.7
(17.2)
2.4-3.4
28.7
(37.8)
47.0
(46.5)
3.7-4.6
7.5
(6.7)
25.5
(29.3)
4.9+
1.1
(7.4)
3.7
(5.7)
the NCRH data were based on discussions
with families. The present study allows some
comparison of the two methods. The parents
in our study were asked to indicate the fa-
vorite viewing location of their five-year-old
children. The distance from the center of the
TV screen of this favorite location (201.9 cm)
was closer than the videotaped observed dis-
tance of the typical viewing location (234.7
cm),
t(70)
=
-2.81,
P
<
0.01. The two dis-
tance estimates correlate moderately well,
1'{69)
=
0.61,
P
<0.001. Thus, our data sug-
gest that discussions with parents may pro-
duce a bias toward indicating closer viewing
by their young children than is apparent from
directly observing the children. The slightly
closer viewing of children and adults re-
ported in the NCRH (1968) study may be due
to a slight bias in self-reports. The difference
may also be due to smaller screen sizes in the
earlier study.
Correlations were calculated between so-
cioeconomic status and the physical and be-
havioral variables for all subjects. Higher-
status individuals had smaller televisions,
r(352)
=
0.24,p
<
0.001; viewed from a
greater distance relative to screen size, 1'{356)
=
-0.18,
P
<
0.001 (but not from a greater
absolute distance); and viewed at a smaller
visual angle, 1'{356)
=
0.15,
p
<
0.002. Fur-
thermore, children from higher-status fami-
lies watched fewer hours of TV, 1'{211)
=
0.12,
p<0.05, and sat on furniture more, r(211)
=
-0.11, P
<
0.05. This pattern is consistent
with an interpretation that TV plays a less
central role in families of higher socioeco-
nomic status than it does in families at lower
socioeconomic levels.
DISCUSSION
The major findings are straightforward:
Children sit closer to the TV than do adults
and, as a consequence, view at a larger visual
angle. Children are more variable in their
viewing locations than are adults and are
considerably less likely than adults to sit or
lie on furniture while watching TV. It should
be pointed out that viewers routinely time-
share TV viewing with other activities. Chil-
dren's time-shared activities are frequently
more active than are those of adults. As such,
children are more likely to be on the floor
rather than on furniture. Since children's
resting focal length tends to be shorter than
that of adults, it is also possible that children
choose visually "comfortable" viewing posi-
tions that are closer than those chosen by
adults (Aslin, Dobson and Jackson, 1982; Si-
monelli, 1983).
Regardless of age, the best predictor of
viewing location is the viewer's tendency to
view from furniture. Because virtually every
TV viewing room had furniture arranged
near the periphery of the room, viewing TV
by guest on February 26, 2014hfs.sagepub.comDownloaded from
TV VIEWING DISTANCES
from furniture generally puts the viewer at a
greater distance and a smaller visual angle.
Reasonably, viewers who had more space
within which they could watch TV placed
themselves farther away from the TV than
did viewers who had less space. Although
room size and percentage of time on furniture
were not related to socioeconomic status, in-
dividuals of higher socioeconomic status
owned smaller TVs and watched from greater
relative distances and at smaller visual an-
gles. There were, in general, no age trends
associated with viewing angle, and only one
variable (screen width) predicted viewing
angle, and that was in children only. Finally,
the present observations correspond well
with survey data collected during the 1960s.
The present study was intended to be de-
scriptive and not a test of any particular theo-
retical or applied issues. There are, neverthe-
less, a number of implications of the findings.
First, there was some evidence in the present
data that viewers chose their locations in
order to achieve a perceptually optimal vi-
sual angle. For example, larger screen width
predicted greater viewer distances from the
TV after the relationship of room area was
removed. Although there has been specula-
tion on such an optimal frame size (e.g.,
McVey, 1970), there has been little actual re-
search using video stimuli. Enoch (1959) re-
ported 9 deg as optimal for visual search of
aerial photographs, and Saida and Ikeda
(1979) found 11.5 deg to be optimal for rapid
identification of 35-mm slides. Given the
quickly paced editing of commercial televi-
sion, there may in fact be an optimal visual
angle, perhaps within parafoveal vision, for
rapid perception of video images. Sixty per-
cent of children and 91% of adults in the
present study typically viewed TV so that a
fixation at the center of the screen framed the
screen within parafoveal vision (estimated at
10 deg horizontally; Ditchburn, 1974).
Regardless of whether there may be an op-
August, 1985-475
timal visual angle for watching television,
practical considerations such as room size
and the location of comfortable furniture ac-
count for viewing location to a much greater
extent. The tendency to view TV from exactly
the same location on a given piece of furniture
day after day especially characterizes adults.
This consistency is suggestive that new tele-
vision services such as videotext should care-
fully consider viewer habits in designing text
and graphics for optimal readability. The
issue is also relevant to the design of text for
future high-resolution screen technology. Ac-
cording to Smith (1979), 100% legibility of
printed text is achieved when letters sub tend
0.007 rad vertically with progressive deteri-
oration of legibility at smaller angles. Ap-
plying Smith's (1979) criterion to the data of
the present study, high-resolution videotext
letters should be at least 3.8 cm high to be
completely legible to 90% of adult viewers.
Presen today television screen technology
would probably require even larger letter
sizes. Presenting smaller text would presum-
ably require at least some adults to change
their viewing habits and/or to rearrange the
furniture in the viewing room.
Finally, there have been recurrent concerns
about the physical effects of television on
children, leading to numerous warnings to
parents that children should view farther
than 1.83 m from the TV screen (e.g., Moody,
1980; Rutstein, 1974; Winn, 1977). Regard-
less of the present-day validity of these con-
cerns (see, for example, Rirning and Aitken,
1982; Nashel, Korman and Bowman, 1982),
it is interesting to note that a decade and a
half ago about 45% of children under 15years
viewed from less than 1.83 m. In our sample,
about 35% of children under 15 years viewed
from less than 1.83 m. Intense publicity and
numerous official warnings over the years
may have reduced the occurrence of children
viewing television at extremely close dis-
tances.
by guest on February 26, 2014hfs.sagepub.comDownloaded from
476-August, 1985
ACKNOWLEDGMENTS
This research was supported by grants to D. R. Anderson
from the National Institute of Mental Health (NIMH), the
National Science Foundation, the John and Mary Markle
Foundation, and by a Research Scientist Development
Award from NIMH to D. R. Anderson. We would like to
thank Leah Larkey for deriving the constant visual angle
curves of Figure 4 and Vahid Kaviani for plotting Figure
4. Many people contributed to the data collection and de-
sign of the larger project of which this report is a part:
Marina Buckley, Harold Byrd, Peter Crown, Sharon Dav-
enport, Catherine Fischer, Elizabeth Lorch, Pearlie Pitts,
Robin Smith, and Caleb Weissberg. We especially would
like to thank the families who made this work possible.
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