Journal
of
Personality
and
Social Psychology
1969,
Vol.
13. No. 2,
83-92
SOCIAL ENHANCEMENT
AND
IMPAIRMENT
OF
PERFORMANCE
IN THE
COCKROACH
1
ROBERT
B.
ZAJONC,
2
ALEXANDER
HEINGARTNER,
AND
EDWARD
M.
HERMAN
8
Institute
for
Social
Research,
University
of
Michigan
Maze
and
runway performance
of
cockroaches
was
observed under solitary
and
social conditions
in an
attempt
to
test
the
drive theory
of
social facilita-
tion.
In
Experiment
I
cockroaches were observed under
two
types
of
social
treatments,
coaction
and
audience.
In
both treatments maze performance
was
impaired while runway performance
was
facilitated when compared
to
per-
formance
of
subjects
in
solitary conditions.
In
Experiment
II the
effects
of
reduced
presence
of
conspecifics
were
investigated.
Experiment
I
generated
results
that
were
in
support
of the
hypothesis
that
the
mere presence
of
conspecifics
is a
source
of
general arousal
that
enhances
the
emission
of
domi-
nant responses.
The
results
of
Experiment
II
suggested
that
partial presence
of
conspecifics
may
have distracting
effects.
About
35
years
ago
Gates
and
Allee
(1933)
reported
a
study
on the
maze learning
of
isolated
and
grouped cockroaches
in
which
they observed
a
clear
inferiority
of
perform-
ance
of the
grouped subjects. Gates
and
Allee
attributed these
effects
to
distraction, saying
that
cockroaches learning
in
groups were
responding
not
only
to the
physical topog-
raphy
of the
maze
but to the
social situa-
tion
as
well,
and
that
the
"chemical traces
introduced
by one of the
other
roaches simul-
taneously occupying
the
maze
may
have acted
to
interfere with orientation [Gates
&
Allee,
1933,
p.
357]."
Other studies using animal
or
human subjects
also
found
a
deterioration
of
performance under social conditions
(Al-
lee &
Masure, 1936;
Klopfer,
1958;
Pessin
&
Husband, 1933).
In
agreement with Gates
and
Allee, Jones
and
Gerard (1967) have
recently ascribed
all
these
effects
to
distrac-
tion.
However,
equally prevalent
are
data show-
ing
improvement
in
performance
as a
function
of
social stimuli.
These
socially facilitated
increments
in
performance
are
usually
found
for
behaviors
that
are
either very well learned
research
was
supported
by
Grant GS-629
from
the
National
Science Foundation.
The
authors
wish
to
express their gratitude
to
Susan
DeLong,
Judith
Johnson,
and
Barbara
Morcland
for
their
assistance
in
various phases
of
this research.
2
Requests
for
reprints should
be
sent
to
Robert
B.
Zajonc,
Institute
for
Social
Research,
University
of
Michigan,
Ann
Arbor, Michigan 48106.
3
Now at the New
School
for
Social
Research,
New
York,
N.
Y.
or
instinctive. Thus,
for
instance,
in
experi-
ments
using
human subjects, skilled
per-
formance
on
pursuit rotor (Travis, 1925),
accuracy
in a
vigilance
task
(Bergum
&
Lehr, 1963), scores
on
chain-association,
vowel
cancellation,
and
multiplication tasks
(Allport,
1924;
Dashiell,
1930),
and
latency
of
word associations
(Matlin
&
Zajonc, 1968)
have
all
been shown
to
improve under social
conditions.
Studies using animal subjects
found
social
increments
in
eating (Bayer,
1929;
Fischel, 1927; Harlow, 1932; Tolman
&
Wilson,
1965),
drinking (Bruce, 1941),
bar
pressing
(Stamm,
1961), copulating
(Larsson,
1956), exploring
(Simmel,
1962),
nest building (Chen, 1937),
and
running
(Scott
&
McCray,
1967).
It has
recently been suggested (Zajonc,
196S)
that
these seemingly conflicting results
can be
reconciled
if it is
assumed
that
the
presence
of
others
is a
source
of
general
drive
(D). While
the
presence
of
others
can
certainly
be a
source
of
specific
cues,
of
rein-
forcement,
and of
rather specific excitation
(as in
mating
or
aggression,
for
example),
and
it can
therefore
direct;
behavior,
it is
also
a
source
of
nonspecific arousal,
and
hence
acts
as
a
general
energizer
of all
responses
that
are
likely
to be
emitted
in the
given situation.
The
degree
of
such
an
arousal need
not be
intense,
of
course. Nevertheless,
it is
assumed
that
its
effects
would
be
those
that
are
pre-
dicted
by the
Spence-Hull
drive theory
(Spence, 1956).
If the
animal's
dominant
83
84
R.
B.
ZAJONC,
A,
HEINGARTNER,
AND E.
M.
HERMAN
responses
are
appropriate
from
the
point
of
view
of the
experimental
situation,
the
pres-
ence
of
others
will
enhance
them;
and the
resulting performance will appear
as
being
improved.
If
these
dominant responses
are
largely inappropriate, however, performance
in
the
presence
of
others
will appear
as
being
impaired.
Thus,
for
instance,
if the
given
stimulus
situation elicits
in the
animal
domi-
nant responses
that
are
connected with eat-
ing,
while
the
experiment "requires"
the
ani-
mal
to
delay
or
suppress
instrumental
re-
sponses leading
to
eating—as
is the
case
in
DRL
(differential reinforcement
of low
rates)
training—the
presence
of
conspecifics
will
work
against
the
experimental
requirements,
and
"performance" will appear
to
suffer.
Such
an
effect
has
indeed been obtained
(Wheeler
&
Davis,
1967).
On the
other hand,
if
the
experimenter
is
interested
in
establish-
ing
high response
rates
using continuous
re-
inforcement,
and if the
total experimental
situation also elicits dominant responses
that
are
connected with eating,
the
presence
of
others
will
appear
to
have
beneficial
conse-
quences. Hence,
it is not
performance
but the
emission
of
dominant
responses, whatever
they are,
that
is
"facilitated"
by the
social
stimulus.
If
information about
the
subject's response
hierarchy
were
available
prior
to the
tests
of
social
effects,
the
drive theory
of
social
fa-
cilitation could
be
given
a
critical
test.
Such
methods have been used with humans (Cot-
trell,
Rittle,
&
Wack,
1967;
Zajonc
&
Sales,
1966),
and the
evidence obtained
was in
substantial agreement with
the
drive theory
of
social
facilitation.
But
procedures
of
this
sort have
not
been employed with animal sub-
jects.
Gates
and
Alice's
(1933) experiment lends
itself
to
some modifications which should
generate
useful
information
for the
drive
theory
of
social
facilitation.
In
their
experi-
ment
Gates
and
Alice
(1933) used
an E-
shaped maze suspended over water. Light
served
as a
noxious stimulus,
while
an
opaque
bottle located
in the
central portion
of the
maze provided
the
subjects with
the
only
means
of
escape.
The
procedure entailed
placing
the
cockroach
(or
cockroaches)
at
one of the
terminals
of the
maze
and
observ-
ing
the
time required
to
reach
the
goal bot-
tle. Because
of the
many
spatial
alternatives
available—at
first all
equally
inviting—many
response tendencies were elicited
that
were
not
correct.
In
fact,
of the
many
ways
in
which
the
cockroach could proceed
in the E-
maze, only
one led to
escape,
and
hence
to
what
the
experimenter would consider
as
"appropriate
behavior."
To the
extent
that
the
presence
of
conspecifics
did act as a
source
of
general
drive (D),
these
many
"inappropriate"
response tendencies were
energized, delaying
the
emission
of the ap-
propriate one.
If
one
could contrive
a
situation
in
which
the
cockroach's response tendencies would
be
largely
"correct"
or
"appropriate,"
an
incre-
ment rather than
a
decrement
in
performance
should
be
obtained under social conditions.
In
comparison with maze performance, this
situation
would
provide
a
rather stringent
test
of the
drive theory
of
social
facilitation.
The
straight runway with
the
noxious stimu-
lus
at the
start
and the
means
of
escape
at
the
goal
can
serve this purpose rather well.
Such
a
straight
runway,
properly
constructed,
does
not
prompt
the
cockroach
to
turn,
for if
it
turns
it
must
only
face
the
noxious
light.
The
entire stimulus situation
is so
contrived
that
the
dominant
tendencies
that
are
elicited
consist
of
running away
from
the
start
box
and
directly toward
the
goal box.
The
present
paper reports
two
experiments
in
which
the
performance
of
cockroaches
in a
maze
and in
a
runway
was
compared under various social
conditions.
In all
these experiments socially
mediated
performance decrements
in the
maze
and
socially mediated increments
in
the
straight runway were expected.
EXPERIMENT
I
This
experiment
had two
major purposes.
The first was to
test
the
drive theory
of
social
facilitation.
To
accomplish this purpose
paired
and
isolated cockroaches were
ob-
served
as
they
performed
in a
maze
and as
they performed
in a
straight runway.
As in
the
experiment carried
out by
Gates
and
Allee
(1933),
the
social variable
was
manip-
ulated
by
having
the
subjects traverse
the
SOCIAL
ENHANCEMENT
AND
PERFORMANCE
IN THE
COCKROACH
maze
or the
runway alone
or in
pairs,
that
is,
ble
effects
of
others' presence:
its
energizing
in
coaction, However, this experimental
ma-
effects
and its
directive
(or
cue)
effects.
Two
nipulation,
which
has
been used
in
nearly
all
animals using
the
same maze
or
runway
may
experiments
on
social facilitation with
ani-
affect
each
other's
behavior because they
act
mals,
may
lead
to a
confounding
of two
possi-
as a
source
of
arousal
for
each other,
or be-
GOAL
GOAL
/
a^"«
T
'
""
~
a
START!
1
^*
—
'
RUHWAY
\
\
\
\
\
/
_•"
'•>•*
•^
/
C
./Floodlight
LJ
START
-^'floodlight
MAZE
A.
COACTION
A.
COACTION
GOAL
GOAL
A
Floodlight
B.AUDIENCE
FJG.
1,
Diagrams
of
runways
and
mazes
used
in the
coaction
and in the
audience
treatments
of
Experiment
I.
86
R. B.
ZAJONC,
A.
HEINGARTNER,
AND E. M.
HERMAN
TABLE
1
RUNNING
TIME
AND
STARTING LATENCY
IN
SECONDS
FOR
SUBJECTS
TESTED
ALONE,
IN
COACTION,
AND
IN
THE
PRESENCE
OE AN
AUDIENCE
Treatment
Coaction
Starting
latency
Running time
Audience
Starting latency
Running
time
Both
treatments
Starting latency
Running
time
Task
Runway
Alone
8.2S
(8)
40.58
(8)
14.80 (10)
62.65
(10)
11.89 (18)
52.84
(18)
Social
6.88
(8)
32.96
(8)
9.35 (10)
39.30
(10)
8.25 (18)
36.48
(18)
Maze
Alone
10.56
(8)
110.45
(8)
37.55
(10)
221.35
(10)
25.56
(18)
172.06
(18)
Social
11.19
(8)
129.46
(8)
22.75 (10)
296.64
(10)
17.61 (18)
222.34
(18)
Note.—Averages
of
medians. Figures
in
parentheses
indicate
the
number
of
roaches
in
each cell.
cause they emit responses
that
may be
imi-
tated.
The
second purpose
of the
present
experiment, therefore,
was to
determine
if
socially
mediated
effects
obtained
in
cock-
roaches
when
the
subjects could
not
profit
from
directive cues provided
by
companions.
Hence, while
the
social variable
in one
group
of
subjects
was
manipulated
by
means
of
coaction,
in the
other group
it was
manipu-
lated
by
providing
an
audience,
in
order
to
eliminate
all
cues connected with
the
pres-
ence
of
conspecifics
that
may
have been task
relevant
and may
have
influenced
the
sub-
jects'
behavioral
choices
rather
than
his
response
vigor.
If
similar
socially
mediated
effects
were obtained with
an
audience
as
with coaction,
the
drive theory
of
social
fa-
cilitation would receive more unequivocal sup-
port
than
had
these
effects
been
obtained
under
the
conditions
of
coaction
alone.
Method
Subjects,
Seventy-two
adult
female
cockroaches
(Blatta
orient-alls)
were
used,
4
and for at
least
1
week prior
to the first
experimental trial they were
housed
in
individual mason
jars
supplied
with
screened
lids.
They
were maintained
in
dark
quar-
ters with
a
relatively constant temperature
of
about
75
degrees
Fahrenheit.
The
insects were
fed an ad
libitum diet
of
peeled
and
sliced apples.
*The
authors
are
grateful
to
Louis
M.
Roth
of
the
United States Army Natick Laboratory
who
was
kind
enough
to
supply
the
subjects
for the
audience
treatment.
The
subjects
in the
coaction
treatment were obtained
from
the
Carolina Bio-
logical
Supply
Company,
Apparatus.
The
basic apparatus
is
shown
in
Figure
1.
It
consisted
of a 20 X 20 X
20-inch clear
plexi-
glass
cube
outfitted
so as to
house
either
a
maze
or
a
runway.
A
ISO-watt
floodlight
served
as a
source
of
noxious stimulation.
In the
center
of
each
verti-
cal
wall
of the
plexiglass
housing,
8i
inches
from
the
top,
was a
rectangular
if
X
J-inch
opening,
which could
be
closed
by
means
of a
guillotine
gate
made
out of
sheet
metal.
A set of
tracks
on the
exterior
of
uach
opening served
as a
shoe
for a
goal
box
or a
starting box, damping
it firmly in
place
against
the
wall opening.
Both
the
goal
box and
the
starting
box
were made
of
4-inch clear plexi-
glass tubing.
A
square
flange
that
could
slide
into
the
shoe
on the
vertical wall
of the
housing
was
affixed
to the
opening
of the
boxes, while
the
other
end
of the
tubing
was
sealed with
J-inch
clear
plexiglass.
The
maze
and the
runway could
be
suspended
in
the
housing
flush
with
the
goal boxes
and the
starting boxes. Both
the
runway
and the
maze were
made
of
black bakelite
floor
2
inches wide,
with
walls
made
of
clear
plexiglass,
1
inch
high.
The
runway
and the
maze were provided with clear
plexiglass
tops 4-inch thick.
The
runway consisted
of
a
straight
track
running
between
two
opposite
vertical
walls,
and was 20
inches long.
The
maze
was
made
of two
runways, placed
in the
same plane
and
perpendicular
to
each other,
thus
forming
a
cross
with
the
walls
of the
intersection removed.
The
lengths
of the
paths
in the
runway
and in the
maze, namely those leading
from
the
starting
box to
the
goal
box or to a
cul-de-sac, were
20
inches.
The
guillotine gates
that
separated
the
starting
and
goal boxes from
the
runway
or
maze were made
of
galvanized
sheet metal.
To
attract
the
roach
to
the
goal
box an
opaque cover, painted
flat
black
on
the
inside,
was
placed
over
the box
making
its
interior
dark.
A flat
black
posterboard,
covering
the
entire
20 X
20-inch area,
was
hung
on the
wall
which
held
the
goal box.
SOCIAL ENHANCEMENT
AND
PERFORMANCE
IN THE
COCKROACH
87
For
the
groups
in
which
the
social variable
was
manipulated
by
means
of a
passive audience four
9 X 9 X
1-inch boxes with plexiglass sides
and
tops
and
bakelite
floors
were used. These boxes were
placed inside
the
plexiglass cube housing
in
such
a
manner that their
floors
were
flush
with
the floors of
the
runway
or the
maze
and
their sides directly
contiguous
with
the
walls
of the
runway
or the
maze. When these boxes were
in
position almost
the
entire extent
of
walls
of the
runway
or
maze were
in
direct contact with
the
sides
of the
audience
boxes.
Air
holes
in the
sides
of the
boxes lined
up
with
air
holes
in the
walls
of the
runway
and the
maze
to
allow transmission
of
olfactory
cues.
Procedure.
Before
each trial
the
runway
(or the
maze)
was
swabbed with alcohol which
was
allowed
to
evaporate thoroughly.
The
starting
box and the
goal
box
were swabbed
in the
same manner
before
each
set of 10
trials.
The
roach
was
transferred
from
its
home
jar to the
starting
box
which
had
been
covered with
an
opaque container similar
to
that
which
also
covered
the
goal box.
Each
trial
began
by
removing
the
cover, turning
on the flood-
light,
and
removing
the
guillotine door separating
the
opening
in the
starting
box
from
the
runway
or
the
maze.
The floodlight was
always
in
line with
the
runway
or the
maze
and 10
inches directly
be-
hind
it. No
light other than that provided
by the
floodlight
was
present
in the
experimental room.
The
trial
was
terminated when
the
cockroach
(or the
pair
of
cockroaches) entered
the
goal
box and the
guillotine
gate
was
lowered behind
it (or
them),
or
in
5
minutes—whichever
was
earlier.
The
guillotine
gate
was
always lowered immediately
after
the
roach's last
leg
crossed
the
entrance
of the
goal
box.
In the
coaction treatment
the
starting latencies
and the
running times were scored
for
each subject
individually, although
the
gate
was not
lowered
until
the
last member
of the
pair entered
the
goal
box.
Thirty-two
animals served
in the
experimental
treatment involving coaction
5
and 40 in the
treat-
ment involving audience.
In
each
treatment
half
of
the
roaches worked
in the
runway
and
half
in the
maze.
In
addition,
within each combination
of
treatment
and
task, half
of the
animals were
run in
the
alone condition
and
half
in the
social condition.
In the
coaction treatment
the
subjects
were placed
into
starting boxes
in
pairs.
For
purposes
of
identi-
fication
they were marked with airplane dope,
one
white
and one
blue.
In the
audience treatment
10
adult
female
Blatta
orient
alls,
which were previ-
ously housed
in
common quarters
of the
laboratory
colony,
were placed
in
each
of the
four
audience
boxes.
The
control group
of 20
roaches, which
was
not to be
exposed
to a
passive audience, worked
with audience boxes
in
position,
but
empty
and
clean.
AH
roaches
run in the
audience treatment
and
in
their proper control conditions
were
run
indi-
6
This
treatment
constitutes
a
partial replication
of
a
previous
experiment,
reported elsewhere (Za-
jonc,
1968).
vidually. Starting latencies
to the
nearest second
and
total
running
tunes
to the
nearest
tenth
of a
second were recorded. Starting latency consisted
of
the
interval beginning
with
the
opening
of the
guillotine
gate
of the
starting
box and
ending
at the
time
the
last part
of the
roach's body
left
the
start-
ing
box.
In all
treatments
and
conditions
the
sub-
jects were given
10
consecutive trials,
all
separated
by
1-minute
intertrial
intervals.
Results
Because starting latencies
and
running
times
are
generally skewed,
the
scores sub-
jected
to the
analysis
of
variance consisted
of
median
times computed over
the 10
trials
performed
by
each subject.
The
averages
re-
ported throughout
this
paper
are
averages
of
these median times.
Table
1
shows
the
entire
results
of the
experiment,
and
Table
2
shows
the
analysis
of
variance
of
these data, Above
all,
it is
clear
that
with respect
to
starting
latencies
all
effects
fail
to
reach acceptable
levels
of
significance.
It was
considered
that
leaving
the
starting box,
which,
it
will
be
recalled,
was the
nearest
to the floodlight, was
a
relatively simple
task
for the
roach,
compa-
rable
to
traversing
a
straight runway.
There-
fore,
under
the
coaction treatment, starting
latencies should
be
shorter
in the
social con-
dition
than
in the
alone condition, regardless
of
whether
the
subjects
are
entering
the
maze
or
the
runway. Under
the
audience treatment,
however, there
are no
social cues
in the
starting
box in the
social
as
well
as in the
alone condition
and we
would, therefore,
not
expect strong
effects
associated with either
treatments
or
conditions. While
the
results
are not
significant,
we
note
from
Table
1
that
the
task
may
have
affected
starting
latencies, with
the
relevant
F
ratio nearly
reaching
an
acceptable level
of
significance.
The
total
running
times show patterns
that
are
quite consistent with
the
drive theory
of
social facilitation.
Relevant
here
is the
sig-
nificant
interaction between
the
conditions
and
tasks
(F=7.5T,
df
=
1/64,
p<
.01).
Roaches running
the
maze
in
coaction
re-
quired
longer times
than
roaches running
in
isolation.
This
result replicates
the findings
of
Gates
and
Allee
(1933). However,
the
effects
of
coaction
are
reversed
for the
run-
way.
Here
the
coacting
roaches
perform
more
quickly
than
the
solitary subjects.
And the
88
R. B.
ZAJONC,
A.
HEINGARTNEE,
AND E. M.
HERMAN
TABLE
2
SUMMARY
OF
ANALYSES
OF
VARIANCE
FOR
DATA
IN
TABLE
1
Source
Alone
vs.
social
(A)
Runway
vs.
maze
Coaction
vs.
audience
(C)
AXB
A
X C
B
X C
A
X B X C
Error
rf/
1
1
1
1
1
1
1
64
Starting
latency
MS
603.78
2386.25
2514.87
83.42
422.50
968.58
143.14
900.36
F
<1
2.650
2.793
<1
<1
1.076
<1
Running
time
MS
5180.48
418826.03
104373.47
19977.75
1823.85
69258.45
5764.66
2640.11
F
1.962
158.639
39.533**
7.567*
<
1.000
26.233**
2.183
**
p <
.001.
same
pattern
of
results
prevails
for the
audi-
ence
treatment.
Hence
the
three-way interac-
tion
was not
significant.
The
analysis
of the
above results also shows
that
the
running times
and the
latencies
are
substantially shorter
in the
coaction animals
than
in the
audience groups. Unfortunately,
because
these subjects came
from
different
colonies,
we are
unable
to
determine
from
the
data
alone whether these
differencs
are due to
the
diverse origins
of the two
groups
of
ani-
mals,
or
whether they have something
to do
with
the
experimental treatments.
It is a
rather plausible conjecture
that
the
differ-
ences
are
attributable
to the
former
factor
because
of the
consistently longer running
times
of
roaches
in the
control groups
of the
audience
as
compared
to the
coaction
treat-
ment.
EXPERIMENT
II
In the first
experiment
it was
shown that
the
presence
of an
audience
of
conspecifics
is
a
sufficient
condition
for the
enhancement
of
dominant responses, such
that
the
perform-
ance
of the
subject
in a
one-alternative
task
is
improved
and the
performance
of the
sub-
ject
in a
multialternative
task
is
impaired.
But the
variable,
"presence
of
conspecifics,"
is
certainly
not
precise either
from
a
theo-
retical
or
methodological point
of
view.
What
are the
essential
and
critical features
of
"presence
of
conspecifics"
that
produce
these
effects?
What
is the
nature
of the
social
stimulus
that
elicits these
effects
and has the
capacity
of
increasing general arousal? Com-
plete
answers
to
these
questions
must
await
a
great deal
of
research
not
only
on the na-
ture
of the
social stimulation involved
in
social
facilitation
effects
but
also
on the
nature
of the
arousal
that
is
brought about
by
the
social stimuli.
But as a first
step
we
may
inquire about
the
minimal conditions
which
are
sufficient
for
producing social
facilitation
effects.
Tolman
(1965)
found
that
feeding
behavior
of
young chicks
was
facilitated
by the
presence
of a
companion
separated
from
the
subject
by a
plexiglass
partition,
and
also
by
feeding
the
subject
in
front
of a
mirror.
These
increments, how-
ever, were
not as
impressive
as
those obtained
with
a
coacting companion.
Tolman
(1968)
regarded such socially mediated
effects
pri-
marily
in
directive (cue)
terms.
Hence
he
accepted
as
more likely
the
hypothesis
that
it
is
the
behavior
of the
companion
rather
than
its
mere presence which produces increments
and
decrements
in
performance. Animal
re-
search, especially
on
feeding
behavior, sup-
ports
his
contention. However, results
of Ex-
periment
I
with audience show
that
even when
the
conspecific
companion does
not
emit
be-
havior
which
can be
used
by the
subject
to
guide
the
course
of his
action,
effects
which
are
consistent with
the
drive theory
of
social
facilitation
are
obtained.
Experiment
II
attempted
to
determine
if
socially mediated
effects
such
as
those
ob-
tained
in
Experiment
I
would
be
produced
if
the
immediate presence
of
conspecifics were
somehow
curtailed
or
reduced.
Two
treat-
ments
were employed.
In
both treatments
SOCIAL
ENHANCEMENT
AND
PERFORMANCE
IN THE
COCKROACH
89
there
were
no
other roaches besides
the
sub-
ject.
Both dealt with some components
of
the
presence
of
conspecifics,
one
emphasizing
its cue
effects,
the
other emphasizing
its en-
ergizing
(general arousal)
effects.
Thus,
in
the
former
the
insects
ran in
mazes
and
run-
ways
which
were
outfitted
with
mirrors
alongside
their vertical walls.
In the
second
treatment regular runways
and
mazes were
utilized,
but the
animals were stimulated
by
the
presence
of
olfactory
cues associated with
their
conspecifics.
These treatments were com-
pared with
one in
which
the
insects were
observed
under solitary
and
socially neutral
conditions.
Method
Subjects.
One
hundred
and
eighty female
Blatta
orientates
obtained
from
the
Carolina Biological
Supply Company were employed
in the
present
experiment.
All
insects were housed
in
individual
mason jars
for 4
days
prior
to the
experiment.
One
third
of the
subjects were assigned
to the
mirror
treatment
(Mi),
one-third
to the
odor treatment
(Od),
and
one-third
to the
alone treatment
(Al).
In
each treatment, half
of the
subjects
(30)
were given
tests
in the
straight runway
and
half
in the
maze.
Apparatus.
The
apparatus
from
Experiment
I, in
which
modifications were made
to
allow tests under
the
requirements
of the
experimental treatments,
was
employed.
In the Mi
treatment
a
runway
and
a
maze were used which were equipped with
re-
flecting
half-aluminized
film
affixed
to the
entire
extent
of the
walls. Otherwise
the
apparatus
was the
same
as in the
alone treatment
of
Experiment
I. In
the Od
treatment
the
regular runway
and
maze
from
the
audience treatment
of
Experiment
I
were
used which,
it
will
be
recalled,
had
holes drilled
in
their walls.
An
olfactory social stimulus
was
pro-
vided
by
placing
an egg
carton impregnated with
the
odor
of
conspecifics
inside
the
housing
of the
apparatus
and 4
inches directly beneath
the
maze
or
the
runway.
The
egg
carton
was
thoroughly impreg-
nated
with
the
odors
of
conspecifics
by
having
it in
the
quarters
of the
colony
for
several
days prior
to
the
tests.
Several cartons were
kept
in the
quarters
of
the
cockroach colony during
the
course
of the
experiment,
and
during each testing session
a
freshly
impregnated
carton
was
always used.
The Al
treat-
ment
was the
same
as the Od
treatment except that
a
fresh
clean
egg
carton,
not
impregnated with
cockroach odor,
was
placed
4
inches beneath
the
runway
or the
maze.
The
same procedure
was
used
for
scoring latencies
and
running times
as in
Experi-
ment
I.
Results
Table
3
shows
the
data
from
Experiment
II. It may at first be
noted
that
under
the
TABLE
3
RUNNING
TIME
AND
STARTING
LATENCY
IN
SECONDS
FOR
SUBJECTS
TESTED
ALONE,
WITH
MIRROR,
AND
IN THE
PRESENCE
OF
CONSPECIFIC
ODOR
Treatment
Mirror
Starting
latency
Running
time
Odor
Starting latency
Running
time
Alone
Starting latency
Running
time
Task
Runway
27.38
77.21
20.00
69.53
22.67
55.67
Maze
28.88
160.71
24.97
245.72
18.33
219.63
Note.—Averages
of
medians.
These
means
arc
based
on 30
independent
observations
in
each cell.
present
experimental treatments
the
latencies
do not
differ
across tasks
(F < 1,
dj
—
I/
174).
Such
a
tendency
was
present
in
Experi-
ment
I,
although
it
also
did not
attain
an
acceptable level
of
significance.
The
latencies
are
also
fairly
uniform
across treatments.
The
relevant
F
ratio
did not
reach
an
acceptable
level
of
significance
(F =
2.681,
dj =
2/174).
Similarly,
the
interaction between treatments
and
tasks
did not
attain significance.
How-
ever,
with respect
to
total running times both
main
effects
and the
interaction
are
signifi-
cant
(/?
=
4.197,
d}=
2/174,
p <
.OS
for
treatments;
F =
167.925,
#=1/174,
p<
.001
for
tasks;
and F =
7.117,
df
=
2/174,
p
<
.001
for the
interaction between
them).
These
effects,
it
seerns,
are due
primarily
to
the
relatively fast maze running time among
the
Mi
subjects.
In
contrast
to the
previous
experiment,
running times
in the
straight
runway
are not
improved
in the two
social
treatments. Both
the Mi and the Od
subjects
took
longer times
to
traverse
the
runway than
the
Al
subjects. Maze running seems
to
show
a
relative facilitation
for the Mi
treatment
and
an
impairment
for the Od
treatment.
DISCUSSION
The
results
of
Experiment
I
support
the
hypothesis
that
the
presence
of
conspecifics
acts
as an
energizer
of
dominant
responses
in
the
cockroach. There were rather clear indi-
cations
that
enhancement
as
well
as
impair-
ment
of
performance
could
be
obtained with
90
R. B.
ZAJONC,
A.
HEINGARTNER,
AND E.
M.
HERMAN
these insects, depending
on
whether
a
simple
or
a
complex
task
was
used,
and
therefore
depending
on
whether
the
situation
was
more
likely
to
recruit appropriate
or
inappropriate
response
tendencies. While results
on
start-
ing
latencies
failed
to
generate
useful
infor-
mation,
data
on
running times unequivocally
favored
the
drive theory
of
social facilitation.
The
fact
that
performance
in the
runway
was
enhanced
by the
presence
of
conspecifics
does
damage
to the
distraction hypothesis
proposed
by
Gates
and
Alice
(1933)
and re-
introduced
by
Jones
and
Gerard
(1967).
It
must
be
noted
that
the
runway
and the
maze
differed
only
in the
number
of
alternative
turns
available
to the
subject
at the
choice
point,
that
is, 9
inches
from
the
starting box.
The
runway
had
only
one
alternative, while
the
maze
had
three.
In all
other respects
the
two
tasks
and the two
stimulus situations
were
nearly
identical.
6
It
would
not be
parsi-
monious,
therefore,
to
maintain
that
the
dis-
traction
hypothesis applies
to
maze
perform-
ance alone,
for we
would have
to
invoke
a
new
psychological
process
to
account
for the
improvement
of
running
times
in the
runway.
The
results
of
Experiment
I
also eliminated
the
possibility
that
social facilitation
effects
depend
on the
specific
behavioral output
of
the
companion.
In
nearly
all
previous experi-
ments
on
social
facilitation
with animal sub-
jects
the
coaction paradigm
was
employed.
Data
from
these studies
could
therefore
be
interpreted
by
assuming
that
the
companion
emits
behavior which
the
subject
can
imitate.
The
fact
that
the
results
in the
audience
treatment show
the
same pattern
as
those
in
the
coaction treatment indicates
that
specific
directive
cues need
not be
involved
in
socially
mediated performance
effects.
In
fact,
the
effects
obtained
in the
coaction treatment
were
less
pronounced
than
those found
in
the
audience treatment. Simple
effects
tests
on
running
time
data
from
Experiment
I
show
a
strong interaction between conditions (social
versus
alone)
and
tasks
(runway versus
maze)
for the
audience treatment
(F —
9.19,
6
It is
true, however,
as the
reviewer
of
this
manuscript correctly observed,
that
the
maze
did
require
a
right
(or a
left) turn
of the
subject, while
the
runway
did
not.
dj
—
1/64,
p <
,01), while
the
same interac-
tion
is
only
of
borderline significance
in the
coaction treatment
(F
=
2.80,
dj
=
1/64,
p
<
.10).
It
should
be
noted,
at the
same time,
however,
that
in a
previous experiment
on
coaction
in
cockroaches (Zajonc, 1968),
us-
ing
subjects
as
their
own
controls, this inter-
action
was
reliable.
Subjects
in the
coaction treatment
did not
show tendencies
to
crowd
or to
form
traffic
jams
in the
runway
and in the
maze. While
they usually
did not
leave starting boxes
or
enter goal boxes
at the
same time,
the
open-
ings
were
sufficiently
wide
to
allow them
to
do
so. The
fact
that
maze performance
was
observed
to
deteriorate
in the
audience treat-
ment
would lead
us to
expect
that
this
de-
terioration
was
socially mediated
in the Co-
action treatment
as
well,
rather than having
been
brought about
by
crowding
or
traffic
jams.
Qualitative observations
of the
roaches
did
not
reveal specific behaviors
by
virtue
of
which
such social
effects
might
be
produced.
Perhaps
the
only
consistent
pattern
found
was
that
the
behavior
of the
subjects
in the
coaction
treatment
was
devoid
of
tendencies
to
follow
or to
imitate.
The
roaches seemed
to
traverse
the
alleys
of the
maze
and of the
runway
in an
apparent ignorance
of
each
other.
In the
audience treatment, too, there
was
nothing detectable
in the
subjects'
be-
havior
to
indicate
that
they oriented toward
the
spectator roaches. But,
of
course, there
is
today only
scanty
information
on the
social
significance
of the
various responses
of the
cockroach.
Another
hypothesis
offered
to
account
for
the
effects
associated with
the
presence
of
conspecifics
assumes
that
they
are not due to
an
increased arousal
but to
calming.
For in-
stance,
Davitz
and
Mason
(19SS)
have
found
that
rats
in an
open
field
test reduce their
fear
responses when
a
previously habituated
rat is
also present.
And
Liddell
(1950)
has
shown
that
neurotic symptoms produced
in
a
young goat
by
means
of a
continuous noxi-
ous
stimulation
are
attenuated when
the
mother goat
is
also present. Bovard
(19S9)
proposed
that
social
stimuli elicit
a
compet-
ing
response "which inhibits, masks,
or
SOCIAL
ENHANCEMENT
AND
PERFORMANCE
IN THE
COCKROACH
91
screens
the
stress
stimulus,
such
that
the
latter
has a
minimal
effect
[p.
269]."
Be-
cause
the
response
of the
posterior hypothala-
mus
initiates
pituitary-adrenal
cortical
and
sympathetic-adrenal
medullar
activity associ-
ated
with stress reactions,
Bovard
argued
that
the
presence
of
another member
of the
same
species must dampen
the
activity
of the
posterior
hypothalamus,
and
thereby dampen
the
stress
reactions
of the
adrenal
system.
It
has
been suggested elsewhere
(Zajonc,
196S)
that
the
reduced stress reactions
may be due
simply
to the
availability
for
imitation
of
coping responses. Hence,
the
experimental
data
associated with reduction
of
fear
which
occurs with
the
presence
of
conspecifics
might
be
best accounted
for by
focusing
upon
the
directive
(cue)
effects
which
are
provided
by
the
conspecifics.
The
situation
in
Experiment
I can
certainly
be
considered
a
stressful
one,
for
the
species
of the
cockroach used
in the
experiment
is
rather
photophobia.
The
effects
observed
in the
coaction
and in the
audience
treatment
are not
consistent with
the hy-
pothesis
that
companions have
a
calming
ef-
fect.
If
this were
the
case
we
would
expect
an
increase
in the
running time
in the
runway
and a
decrease
in the
running time
in
the
maze—results
which would
be
diametrically
opposite
to
those
found
in
Experiment
I. But
such
an
effect
was
found
in
Experiment
II
in
the Mi
treatment.
In
comparison with
the
Al
treatment, these subjects took longer
in
the
runway
and
were faster
in the
maze.
The
Mi
treatment,
it
will
be
recalled,
stresses
the
directive
(cue) properties associated with
the
presence
of
conspecifics.
But in
Experiment
I
there
also
was a
treatment
(coaction)
in
which
cues were available
for
imitation
but in
which
an
actual companion
was
present.
Yet
this
experimental
situation
did not
produce
a
calming
effect.
The
results
of
Experiment
II are
ambigu-
ous.
One
conclusion
to be
drawn
from
these
results
is
that
in
order
for
drive
effects
to
take place
the
presence
of
conspecifics must
be
actual.
Partial
presence, such
as the
pres-
ence
of
olfactory
traces,
was not
sufficient
to
produce
effects
consistent with
the
drive
theory
of
social facilitation.
It
seemed,
on the
contrary,
that
the Od
treatment
generated
results
most
consistent
with
the
distraction
hypothesis.
In
comparison with
the Al
treat-
ment,
the
subjects running
in the
presence
of
the
odor
of
conspecifics
had
longer
times
in
the
maze
as
well
as in the
straight
runway.
The
question immediately arises whether
so-
cial
facilitation
effects
consistent
with
the
drive
theory
of
social facilitation would
be
obtained
in the
presence
of an
immobile audi-
ence.
For
instance,
one
could observe
the
run-
way and
maze behavior
of
cockroaches
in the
presence
of a
dead
or
anaesthetized com-
panion.
The
danger
of
such
an
experiment
is
that
a
dead
or an
immobile cockroach, while
leading
to an
increase
in the
general arousal
level
of the
subject, might
also
elicit
specific
alarm
or
stress responses
that
may
interfere
with
task
performance.
The
problem
of
what
are the
minimal features
of the
presence
of
conspecifics
which
are
sufficient
for
social
facilitation
effects
which
the
drive theory
predicts
is
quite
difficult
from
a
methodo-
logical
point
of
view.
Another
problem associated with social
fa-
cilitation
effects
is
that
concerning
the
nature
of
the
arousal
or
drive
that
increases
in the
presence
of
others. Social facilitation
effects
obtained with human subjects
can be
readily
interpreted
as
caused
by a
motivation
to
suc-
ceed,
a
desire
to be
praised
and
avoid blame,
or
in
general,
by
assuming
that
the
presence
of
others
creates
in the
individual
the
antici-
pation
of
socially positive
or
negative conse-
quences
and
thus increases
the
general arousal
level
(Cottrell,
1968;
Cottrell,
Wack,
Sek-
erak,
&
Rittle, 1968).
Had the
present been
experiments using human subjects
one
could
easily
raise
questions
about
self-disclosure,
evaluation apprehension,
the
approval motive,
etc.
But one finds it
rather awkward
to at-
tribute
this
sort
of
motivation
to the
cock-
roach, even though
we
have
no
idea
if
these
seemingly
spiritless creatures
aren't
vulnerable
to
some
of the
very
same
passions
and
weak-
nesses
which beset
our
sophomore population
of
subjects.
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(Received January
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1969)