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Journal
oj
Experimental
Psychology
1971,
Vol.
87, No. 2,
220-224
EFFECTS
ON
PERFORMANCE
OF
PLACING
A
VISUAL
CUE AT
DIFFERENT
TEMPORAL LOCATIONS WITHIN
A
CONSTANT DELAY
INTERVAL1
J. W.
TOMBAUGH
AND
T. N.
TOMBAUGH2
Carleton
University,
Ottawa,
Ontario
The
effects
of
presenting cues
at
different
times within
a
7.5-sec.
delay
of
reinforcement
interval were studied during
the
acquisition
and
extinction
of a
bar-press response
by
rats.
In
acquisition,
the
three
following
types
of
tem-
poral
placements were
used:
(a) a cue
presented only
at the
beginning
of the
delay
interval;
(6) a cue
occurring throughout
the
duration
of the
delay inter-
val,
and
(c)
a cue
which
was
presented only
at the end of the
interval.
In
extinc-
tion,
each group
was
divided
so
that
half
of the
group received
the cue
condition
and
half
did
not.
In
addition,
a
no-cue control group
was
employed
in
both
acquisition
and
extinction.
In
acquisition
and
extinction,
the cue
conditions
tended
to
produce shorter latencies than
did the
no-cue conditions.
The
extinction
data
further
indicated
that
the
greatest
resistance
to
extinction
was
produced
when
the
offset
of the cue was
associated with
the end of the
delay
interval.
A
secondary reinforcement interpretation
was
advanced
to
explain
these results.
Acquisition
results
from
studies
which
have employed
constant
delay
of
rein-
forcement
consistently have demonstrated
the
following
relationships:
(a)
Perform-
ance
is
inversely
related
to the
length
of
the
delay interval;
(&)
delay-associated
cues
extend
the
temporal gradient
by
increasing
the
maximum length
of the
delay
that
can be
used
effectively
to
establish
a
response;
and (c)
cues tend
to
interact
with
the
length
of the
delay interval
so
that
performance
is
improved more during
long delays
than
with
short
delays (Ren-
ner,
1964). Renner (1964)
has
suggested
that
delay-associated cues should also
lead
to
superior performance
in
extinction.
However, results
from
experiments
which
have
used extinction
data
to
assess
the
delay-cue
relationship have
failed
to
sub-
stantiate
this
prediction when
the
tem-
poral positioning
of the cue has not
been
altered
from
acquisition
to
extinction
(Renner,
1963, 1965).
The
precise temporal location
which
the cue
occupies within
the
delay interval
1
This research
was
supported
by
Grant APA-
0265
from
the
National Research Council
of
Canada.
The
author
gratefully
acknowledges
the
assistance
of
Heather Lindsay
for
running
5s.
2
Requests
for
reprints
should
be
sent
to Tom
Tombaugh,
Psychology Department, Carleton Uni-
versity,
Ottawa, Ontario, Canada.
represents
one
variable
which
may be
critical
in
determining
the
degree
to
which
cues
will
influence
extinction performance.
For
example,
a cue of
short duration placed
at the
beginning
of the
delay interval might
be
expected
to
produce
a
different
effect
from
the
same
cue
occurring
at the end of
the
delay interval. Since
no
experiment
has
attempted
a
comparative
investigation
of
the
effects
of
placing cues
at
different
locations
in the
delay interval,
the
present
study
was
designed
to
perform such
a
comparison.
METHOD
Subjects
Seventy-two nai've
female
albino
rats
of the
Sprague-Dawley
strain purchased
from
the
Holtz-
man
Company were used
as 5s.
They were approxi-
mately
90
days
old at the
beginning
of the
experi-
ment.
Apparatus
Eight experimental chambers were used.
Each
chamber (60.16
cm
long
X
71.12
cm.
wide
X
73.66
cm.
high)
was
constructed
of
1.91-cm.
plywood
and
sound
insulated with acoustical ceiling tile.
A
100-cfm
Dayton blower, located
in the
upper
left-
hand corner
of the
back
wall,
was
used
for
ventila-
tion
and
masking noise.
The 5s
were
tested
in a
Hoeltge HB-11A cage
(24.76
cm.
long
X
20.32
cm.
wide
X
18.41
cm.
high)
mounted
in the
center
of the
chamber.
Illumination
was
provided
by a
12-vdc.
6-w.
lamp
(house
light)
positioned behind
an
opaque
220
