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Abstract

Avoidance conditioning procedures were used to train cats to discriminate intensity differences between successive clicks. The discriminative behavior was applied in a modified method of adjustment to determine a difference limen (DL) for click intensity. The obtained DLs were consistent within and between subjects, and averaged 4.4 db. This value is greater than previously reported intensity DLs for pure tones in cats.
JOURNAL
OF
THE
EXPERIMENTAL
ANALYSIS
OF
BEHAVIOR
BEHA
VIORAL
DISCRIMINATION
OF
CLICK
INTENSITY
IN
CAT'
JAMES
C.
SAUNDERS
PRINCETON
UNIVERSITY
Avoidance
conditioning
procedures
were
used
to
train
cats
to
discriminate
intensity
differences
between
successive
clicks.
The
discriminative
behavior
was
applied
in
a
modified
method
of
adjustment
to
determine
a
difference
limen
(DL)
for
click
intensity.
The
obtained
DLs
were
consistent
within
and
between
subjects,
and
averaged
4.4
db.
This
value
is
greater
than
pre-
viously
reported
intensity
DLs
for
pure
tones
in
cats.
Neurophysiological
studies
involving
chronic
and
acute
macroelectrode
recordings
from
the
auditory
pathway
have
made
extensive
use
of
clicks
as
the
form
of
acoustic
stimulation.
As
a
result,
there
has
accumulated
during
the
past
25
yr,
an
enormous
amount
of
research
literature
describing
the
neurological
events
associated
with
a
click
stimulus.
With
such
a
large
background
of
neurologi-
cal
data,
a
corresponding
body
of
research
con-
cerning
the
behavioral
discrimination
of
clicks
might
be
expected,
but
this
is
not
the
case.
With
the
exception
of
Zwislocki,
Hellman,
and
Verrillo
(1962),
who
described
the
effects
of
pulse
repetition,
duration,
and
number
on
the
threshold
of
audibility,
and
Saunders
and
Hertzler
(1968),
who
described
the
click
in-
tensity
difference
limen
(DL)
in
humans,
in-
formation
concerning
the
psychophysical
pa-
rameters
of
the
click
is
lacking.
Because
a
great
proportion
of
the
neurophysiological
literature
concerning
click-evoked
activity
in
the
auditory
pathway
has
been
derived
from
the
cat,
an
estimate
of
the
behavioral
dis-
crimination
of
click
intensity,
in
this
species,
may
provide
useful
information
for
inter-
preting
the
neural
events.
The
present
study
describes
the
intensity
DL,
for
a
click
stimu-
lus
of
moderate
loudness,
in
the
cat.
METHOD
Subjects
One
female
(J-21)
and
three
male
(J-26,
34,
36)
adult
cats,
each
weighing
about
3.2
kg,
served.
The
external
meatus
of
both
ears
in
all
subjects
were
free
of
wax
occlusions
and
post-experimental
analysis
yielded
no
indica-
tion
of
middle
ear
infection.
At
the
start
of
the
experiment,
none
of
the
cats
had
prior
ex-
perience
with
the
click
stimulus.
Four
months
before
training
began,
each
cat
had
electrodes
chronically
implanted
in
the
left
cochlear
nu-
cleus
and
on
the
dura
over
the
right
auditory
cortex.
During
the
time
that
training
and
testing
occurred,
all
subjects
were
in
excellent
health
and
received
no
medication
for
the
implant.
It
is
assumed
that
the
presence
of
these
electrodes
had
little
effect
on
the
binau-
ral
discrimination
of
click
intensity.
The
pur-
pose
of
these
implants
is
described
elsewhere
(Saunders,
1969).
Stimulus
Conditions
The
timing
controls
on
a
Tektronix
162
waveform
generator
were
set
to
produce
a
saw-
tooth
signal
every
800
msec.
This
signal
was
used
to
trigger
two
Tektronix
161
pulse
gen-
erators.
The
delay
control
on
one
pulse
gen-
erator
was
adjusted
so
that
a
square
wave
pulse
output
occurred
40
msec
after
the
onset
of
the
saw-tooth.
In
a
similar
manner,
an
out-
put
signal
from
the
second
pulse
generator
was
delayed
440
msec.
The
pulse
amplitude
from
each
channel
was
controlled
by
attenua-
tors
connected
in
series
with
each
pulse
gen-
erator.
The
pulses
on
each
channel
were
elec-
trically
combined
in
a
homemade
mixer,
amplified
by
a
McKintosh
MC-40
amplifier,
and
converted
to
clicks
with
a
Jenson
Duax
'This
research
was
supported
by
NIMH,
Public
Health
service
and
Higgins
funds
to
Dr.
E.
G.
Wever,
Department
of
Psychology,
Princeton
University.
Re-
prints
may
be
obtained
from
the
author,
Department
of
Psychology,
Monash
University,
Clayton,
Victoria,
Australia.
951
1969,
12,
951-957
NUMBER
6
(NOVEMBER)
JAMES
C.
SA
UNDERS
Cl
C2
*-AC-KGROUO.ND
SMMUWLUS
*
DISCREINATION
A
STALU
SPEAKEt
_
Li
C2
~~~~~~~~OSCILLOSCOPE
440m.
Fig.
1.
The
apparatus
arrangement
for
producing
two
independent
trains
of
alternately
occurring
clicks.
The
top
part
of
the
figure
depicts
the
two
forms
of
stimulus
conditions.
8-in.
speaker.
In
this
manner,
two
trains
of
alternately
occurring
clicks
were
produced
and
their
intensity
could
be
independently
con-
trolled.
The
interval
between
successive
clicks
was
held
constant
and
continually
monitored
with
a
Hewlett
Packard
(5233L)
interval
counter.
Figure
1
illustrates
the
apparatus
arrangement.
A
pulse
duration
was
empirically
deter-
mined
from
the
waveform
of
the
acoustic
re-
sponse
and,
in
large
part,
depended
on
the
resonant
characteristics
of
the
speaker.
A
Bruel
and
Kjaer
0.25-in.
microphone
was
lo-
cated
22
in.
below
the
speaker
and
the
click
response
detected
by
the
microphone
was
am-
plified
and
displayed
on
a
Tektronix
531
oscilloscope.
The
pulse
duration
control
on
each
pulse
generator
was
adjusted
until
the
waveform
of
the
click
exhibited
a
single,
high
amplitude
spike
with
a
minimum
number
of
low
amplitude
ringing
components.
The
opti-
mal
click
response
for
the
Jenson
speaker
occurred
at
a
pulse
duration
of
0.075
msec.
The
primary
biphasic
spike
of
the
click
lasted
for
0.7
msec
and
the
low
amplitude
ringing
components
continued
for
2.5
msec.
The
high-
est
amplitude
ringing
component
was
approxi-
mately
22
db
below
the
peak-to-peak
amplitude
of
the
primary
component.
The
controls
on
each
pulse
generator
were
carefully
adjusted
so
that
the
waveshape
and
amplitude
of
their
respective
acoustic
responses
were
identical
for
similar
attenuator
settings.
The
intensity
of
the
click
was
calibrated
by
converting
the
peak-to-peak
acoustic
response,
detected
by
the
microphone,
to
db
re
1
dyne/cm2.
Free-
field
calibration
was
accomplished
for
10
posi-
tions
in
the
test
cage,
within
the
vicinity
of
the
cat's
head.
Two
patterns
of
clicks
were
employed
(see
Fig.
1).
The
first
was
a
series
of
constant
inten-
sity
clicks
(-30
db
re
1
dyne/cm2)
that
always
occurred
in
the
testing
environment.
This
condition
was
referred
to
as
the
background
stimulus.
The
second
pattern
was
the
discrim-
inative
stimulus
(DS)
and
occurred
when
the
intensity
of
alternate
clicks
were
increased.
The
louder
of
the
clicks
was
designated
C1
while
the
other,
of
constant
intensity,
was
C2.
The
DS
consisted
of
18
pairs
of
C1
and
C2
and
lasted
14.4
sec.
The
onset
of
the
DS
was
controlled
by
a
set
of
relay
contacts
that
switched
the
output
from
one
pulse
generator
through
a
third
attenuator
(see
Fig.
1).
This
attenuator
was
initially
adjusted
to
increase
the
pulse
amplitude
and
hence
the
click
in-
tensity
by
20
db.
As
the
subject
performed
the
discrimination
task,
the
intensity
difference
(A
I),
in
db,
between
C1
and
C2
was
systemat-
ically
varied
by
changing
the
levels
on
the
third
attenuator.
Careful
calibration
of
the
acoustic
responses
insured
that
click
intensity
952
BEHAVIORAL
DISCRIMINATION
OF
CLICK
INTENSITY
IN
CAT
was
equal
for
DS
or
background
stimulus
con-
ditions
when
all
three
attenuators
were
set
to
equal
levels.
The
relay
controlling
the
DS
was
operated
by
a
solid
state
(Digi-Bits)
logic
circuit
that
timed
the
DS
duration,
adminis-
tered
shock
reinforcement,
and
recorded
the
number
of
correct
and
incorrect
responses.
A
Grason-Stadler
shock
generator
(E6070B)
was
used
to
administer
a
scrambled
shock
reinforcer
to
the
footpads
of
the
cat
as
it
stood
on
a
gridfloor
in
the
test
cage.
The
intensity
of
the
shock
was
empirically
adjusted
to
the
minimal
level
necessary
to
maintain
avoidance
behavior.
This
intensity
never
exceeded
2.0
ma.
A
conditioned
reinforcer
(red
light)
was
located
in
the
test
cage
and
was
always
paired
with
the
occurrence
of
shock.
Training
Procedures
The
procedures
used
to
define
the
DL
for
click
intensity
were
derived
from
the
modified
method
of
adjustment
originally
described
by
Bekesy
(1947).
The
Bekesy
method
requires
a
subject
continually
to
adjust
stimulus
condi-
tions
in
order
to
track
a
sensory
threshold
over
time.
The
present
methods
restructured
the
continuous
threshold
tracking
procedure
to
a
fixed
trial
procedure.
The
various
phases
for
training
the
subjects
to
respond
in
the
presence
of
the
DS,
and
the
application
of
this
response
to
an
intensity
discrimination
task,
were
adapted
from
methods
originally
described
by
Clack
and
Herman
(1963).
All
training
and
testing
took
place
within
a
sound-proof
booth.
The
cats
performed
the
discrimination
task
in
a
wire
mesh
cage
20
in.
by
7
in.
by
14
in.
(508
mm
by
178
mm
by
356
mm).
The
floor
of
the
cage
consisted
of
a
series
of
horizontal
brass
rods
0.25-in.
(6.3
mm)
di-
ameter
and
separated
by
0.5
in.
(13
mm).
The
grid
floor
was
independent
of
the
cage
frame
and
rested
on
a
pivot
point
that
allowed
it
to
rock
0.25
in.
(6.3
mm)
when
depressed
at
either
end.
A
tilt
of
the
floor
momentarily
opened
a
set
of
switch
contacts
and
constituted
the
response
for
a
given
situation.
In
the
first
phase,
each
cat
was
trained
to
avoid
shock
by
making
a
tilt
response
within
14.4
sec
after
the
onset
of
the
DS.
Failure
to
respond
within
this
period
of
time
resulted
in
a
pairing
of
DS
and
shock
which
continued
until
the
cat
caused
the
floor
to
rock.
The
specific
nature
of
the
response
for
both
avoidance
and
escape
behaviors
was
movement
over
the
pivot
point
of the
tilting
grid
floor.
Due
to
the
narrowness
of
the
cage,
the
response,
on
successive
trials,
was
effected
by
the
cat
as
it
moved
either
for-
ward
or
backward
over
the
pivot
point.
As
avoidance
performance
improved,
the
nature
of
the
tilt
response
changed.
Extraneous
motor
activities
gradually
extinguished
until
the
cat
sat
over
the
pivot
point
and
made
the
response
by
simply
leaning
far
enough
forward
or
back-
ward
to
rock
the
floor.
The
tilt
floor
procedure
introduced
a
behavioral
restraint
that
main-
tained
the
position
of
the
auditory
receptors
within
a
controlled
stimulus
field.
Typical
measures
of
click
intensity
about
the
cat's
head
yielded
a
range
no
greater
than
2.1
db.
The
specific
nature
of
the
rocking
behavior,
the
apparatus
employed,
and
the
advantages
it
offers
for
auditory
experiments
have
been
de-
tailed
elsewhere
(Saunders,
1968).
The
inter-
trial
interval
(ITI)
during
Phase
1
was
held
constant
at
50
sec
and
the
cats
were
trained
in
daily,
30-trial
sessions.
Throughout
train-
ing,
the
acoustic
difference
between
C1
and
C2
was
fixed
at
20
db.
Phase
1
continued
until
each
subject
exhibited
a
performance
criterion
of
two
consecutive
sessions
with
at
least
90%O
avoidance
responses.
When
criterion
was
achieved,
the
second
phase
began.
In
Phase
2,
a
trial
light
(white)
and
non-
discrimination
trials
were
introduced.
A
dis-
crimination
trial
occurred
whenever
the
light
was
paired
with
the
DS.
The
non-discrimina-
tion
trial
occurred
when
the
light
was
paired
with
the
background
stimulus
for
14.4
sec.
The
trial
light
thus
served
to
distinguish
discrimi-
nation
and
non-discrimination
trials
from
the
background
stimulus.
The
two
types
of
trials
were
presented
in
a
random
sequence
and
dur-
ing
a
session
each
occurred
approxrmnately
50%
of
the
time.
During
Phase
2,
the
inter-
trial
interval
was
shortened
to
20
sec
and
the
number
of
trials
in
a
session
was
increased
to
60
(30
discrimination,
30
non-discrimination).
Subjects
were
trained
to
respond
differentially
to
the
two
trial
conditions.
The
cat
could
avoid
shock
by
responding
in
the
presence
of
the
DS
on
a
discrimination
trial
(correct
avoid-
ance)
and
by
not
responding
during
a
non-dis-
crimination
trial.
Conversely,
failure
to
re-
spond
on
a
discrimination
trial,
within
14.4
sec,
resulted
in
a
pairing
of
DS
and
shock
until
a
response
occurred.
A
tilt
during
a
non-
discrimination
trial
was
followed
by
a
0.5-sec
shock
and
termination
of
the
trial
(false
posi-
953
JAMES
C.
SAUNDERS
tive).
The
training
in
this
phase
progressed
in
daily
sessions
until
each
subject
exhibited
a
performance
criterion
of
two
consecutive
sessions
of
at
least
90%
correct
avoidance
responses
and
less
than
10%
false
positive
re-
sponses.
When
this
level
of
differential
per-
formance
was
achieved
the
next
phase
was
introduced.
The
sequences
in
Phase
3
were
identical
to
those
described
in
Phase
2,
except
that
stimu-
lus
conditions
were
systematically
modified
and
the
reinforcement
schedule
was
altered
for
threshold
level
performance.
Whenever
the
cat
responded
correctly
during
a
discrimi-
nation
trial,
the
acoustic
difference
between
C1
and
C2
was
reduced
by
2.0
db
on
the
next
discrimination
trial.
A
non-avoidance
response
resulted
in
a
2.0-db
increase
in
A
I
on
the
next
discrimination
trial.
The
difference
between
C1
and
C2
remained
unchanged
if
a
false
posi-
tive
response
occurred.
In
this
way,
the
cat
effectively
tracked
its
discrimination
threshold
over
a
number
of
trials.
To
control
performance
in
the
threshold
region,
the
reinforcement
schedule
was
modi-
fied
so
that
the
subjects
would
not
be
shocked
for
subliminal
conditions.
This
was
accom-
plished
by
using
a
procedure
similar
to
that
employed
by
Clack
and
Herman
(1963).
Rein-
forcement
was
placed
on
a
ratio
schedule
such
that
three
successive
non-avoidance
trials
had
to
occur
before
a
shock
was
delivered.
The
shock
contingency,
however,
was
structured
so
that
each
correct
avoidance
response
sub-
tracted
one
from
the
sum
of
non-avoidance
trials
needed
to
complete
the
3:1
ratio.
Thus,
any
sequence
of
three
non-avoidance
responses
that
increased
A
I
by
6.0
db
would
result
in
90~~~~~~~
0
60
0
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,
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12
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IIII,,,I
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,.,
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II
II
2
4
6
8
10
12
14
16
18
20
22
24
CONSECUTIVE
SESSIONS
Fig.
3.
The
differential
threshold
for
consecutive
threshold
tracking
sessions.
the
administration
of
shock
for
all
subsequent
incorrect
behaviors
at
higher
levels
of
A
I.
During
a
tracking
session,
the
ratio
always
began
from
the
lowest
level
of
A
I.
The
con-
ditioned
reinforcer
(red
light)
continued
to
indicate
incorrect
responses
while
the
shock
was
off,
and
helped
to
retard
extinction
when
the
animal
performed
at
threshold.
Threshold
sessions
typically
lasted
50
trials
or
about
25
to
35
min.
The
testing
in
Phase
3
continued
until
each
subject
exhibited
a
stable
DL
for
10
consecutive
sessions.
RESULTS
Figure
2
illustrates
the
rate
at
which
all
sub-
jects
acquired
the
avoidance
behavior.
These
results
show
that
an
average
of
11
sessions
or
330
trials
was
necessary
before
criterion
per-
formance
for
Phase
1
was
achieved.
As
avoid-
ance
performance
improved,
the
motor
activity
used
to
rock
the
grid
floor
systematically
changed.
When
avoidance
training
was com-
pleted,
the cat
sat
over
the
pivot
point
and
tilted
the
floor
by
shifting
its
weight
either
forward
or
backward
very
quickly.
The
devel-
opment
of
this
behavior
followed
the
same
TRAINING
SESSIONS
Fig.
2.
The
acquisition
rate
in
all
four
subjects.
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
1
1
1
61mm6i"-
954
I
-j
BEHAVIORAL
DISCRIMINATION
OF
CLICK
INTENSITY
IN
CAT
progression
as
that
described
by
Saunders
(1968).
Although
response
latency
was
not
sys-
tematically
recorded,
there
appeared
to
be
a
substantial
number
of
trials
where
the
latency
was
at
least
10
sec.
Long
latency
responses
were
observed
throughout
Phase
2
and
3.
Criterion
performance
for
the
second
phase
was
quickly
achieved,
often
within
several
training
sessions.
The
ease
with
which
the
cats
learned
to
respond
on
only
discrimination
trials
was
rather
surprising.
It
appeared
that
once
the
avoidance
behavior
to
the
DS
was
firmly
established,
little,
if
any,
stimulus
gen-
eralization
occurred
to
the
trial
light.
Unfortunately,
the
rapid
acquisition
of
dif-
ferential
performance
in
Phase
2
was
not
re-
flected
in
the
ability
to
track
stable
thresholds
in
the
third
phase.
Figure
3
shows
the
average
DL
for
all
subjects
on
consecutive
threshold
sessions.
These
data
indicate
that
stable
thresh-
old
performance
was
not
achieved
until
after
Session
13.
The
exponential
nature
of
the
data
plotted
in
Fig.
3
indicate
that
the
cats
quickly
acclimated
to
the
conditions
of
thresh-
old
tracking.
However,
sophisticated
discrim-
ination
performance
required
a
considerable
degree
of
practice.
Figure
4
illustrates
the
performance
of
one
cat
during
a
typical
threshold
session.
The
ordinate
shows
the
intensity
difference
(A
I)
and
the
abscissa
represents
consecutive
discrim-
ination
trials.
Every
threshold
session
began
with
A
I
at
20
db
and
each
track
could
be
characterized
by
a
series
of
correct
discrimina-
tions
early
in
the
session.
Threshold
level
performance
was
indicated
when
the
acoustic
changes
were
relatively
sta-
ble
after
many
discrimination
trials.
The
ses-
J-26
Okq068
S
DLU
SD
J-21
4.2
1.2
J-26
4.6
0.9
J-34
4.9
0.7
J-36
4.1
0.5
11
THRESHOLD
..w.lopfSJlm+~~~~~~~~~~~..
C
SI
1
EC1TIVE
D
ISCRIMINI
TRIA
l1,,1
,
CONSECUTIVE
DISCRIMINATION
TRIALS
Fig.
4.
A
typical
threshold
track
for
one
subject.
The
DL
performance
for
all
subjects
is
shown
in
the
upper
right-hand
corner.
sion
described
in
Fig.
4
indicates
that
J-26
reached
threshold
on
the
ninth
discrimination
trial.
For
the
remaining
27
trials,
its
perform-
ance
maintained
A
I
within
a
6.0-db
range.
The
actual
threshold
for
any
session
was
de-
termined
from
the
mean
intensity
difference
settings
for
the
last
15
discrimination
trials.
Thus,
the
performance
of
J-26
produced
a
DL
of
4.7
db.
A
threshold
could
be
reliably
predicted
after
as
fefw
as
12
to
18
discrimina-
tion
trials.
All
subjects
were
capable
of
pro-
ducing
a
DL
track
within
10
min
and
two
exhibited
reliable
performance
with
the
inter-
trial
interval
as
short
as
9.0
sec.
The
false
positive
(fp)
responses
that
oc-
curred
during
this
particular
threshold
session
are
indicated
in
Fig.
4.
These
behaviors
were
observed
only
while
the
subject
was
perform-
ing
in
the
region
of
threshold.
The
number
of
false
positives
on
any
threshold
session
rarely
exceeded
1%
of
the
total
non-discrim-
ination
trials.
In
the
upper
right-hand
corner
of
Fig.
4
can
be
seen
the
average
threshold
performance
for
the
last
12
sessions.
The
standard
devia-
tion
(SD)
is
also
shown.
The
DL
within
and
between
subjects
exhibited
considerable
con-
sistency.
Figure
5
shows
the
performance
for
all
sub-
jects
when
the
percentage
of
correct
responses,
on
all
discrimination
trials
during
the
last
14
sessions,
were
plotted
against
each
intensity
difference
level.
The
percentage
of
correct
100
!a
z
i
57
LA
0
z
wX
jTHRESHOLD
11~~~~~~~~~~~~~~~
0
1
!
I
I
I
I I
~
~I
2
4 6
8
10
12
14
16
18
20
INTENSITY
DIFFERENCE
(Al)
IN
DB
Fig.
5.
The
DL
determined
from
the
percentage
correct
discriminations
for
all
subjects.
am
U
w
LUI
U-
z
LIJ
zr
955
956
JAMES
C.
SA
UNDERS
responses
increases
rapidly
between
2.0
and
8.0
db.
For
intensity
differences
at
or
greater
than
10.0
db,
performance
never
fell
below
the
90%7
level.
Of
the
127
trials
at
2.0
db,
only
two
correct
discriminations
were
recorded.
When
the
results
are
plotted
in
this
fashion,
the
interval
of
uncertainty
is
clearly
defined
between
2.0
and
10.0
db.
The
differential
threshold
can
be
determined
from
Fig.
5
by
noting
the
intensity
difference
that
would
cause
the
cats
to
respond
on
50%
of
the
dis-
crimination
trials.
An
extrapolation
of
A
I
from
the
50%
correct
response
level
yields
a
DL
of
4.4
db.
This
threshold
compares
favor-
ably
with
the
DLs
computed
for
individual
subjects
during
the
last
12
threshold
sessions.
DISCUSSION
In
part,
the
small
number
of-
studies
con-
cerned
with
the
psychophysics
of
click
stimuli
may
stem
from
difficulties
in
determining
the
parameters
of
this
cue.
The
present
methods
for
specifying
and
calibrating
the
click
are
not
presumed
to
represent
a
"perfect"
proce-
dure.
It
may
be
that
a
"standardized"
click
is
impossible
to
specify.
However,
the
techniques
employed
do
provide
a
convenient
guideline
for
specifying
the
click
output
from
any
trans-
ducer.
The
behavioral
procedures
have
proven
successful
for
training
cats
to
track
a
DL
for
click
intensity.
The
reliability
of
the
threshold
measures
within
and
between
subjects
suggest
that
the
results
represent
a
close
approxima-
tion
to
the
intensity
DL
for
these
stimulus
conditions.
However,
it
must
be
noted
that
the
"yes-no"
situation
has
been
criticized
on
the
grounds
that
it
introduces
a
response
bias
that
may
obscure
the
"true"
sensory
threshold
(Blough,
1966).
Although
it
is
likely
that
some
level
of
response
bias
was
operating
in
the
present
situation,
the
weight
of
this
argument
is
reduced
by
the
occurrence
of
false
positive
responses.
A
response
bias
would
have
elevated
the
threshold
so
that
the
cats
were
always
responding
to
above
threshold
levels
of
the
DS.
Such
a
bias
would
reduce
uncertainty
over
stimulus
conditions
and
preclude
the
occur-
rence
of
false
positive
responses.
The
data,
however,
show
that
the
cats
did
make
false
positive
responses
and
that
these
behaviors
occurred
only
at
threshold
levels
of
A
I.
Thus,
the
occurrence
of
false
positive
responses,
al-
though
infrequent,
diminished
the
influence
of
a
response
bias
and
provided
additional
evidence
that
the
cats
were
performing
near
or
at
their
sensory
threshold.
The
average
DL
of
4.4
db,
obtained
at
a
loudness
level
of
-30
db
re
1
dyne/cm2,
is
considerably
greater
than
the
noise
DL
(Miller,
1947)
or
1.0
kHz
DL
(Riesz,
1929)
in
the
human
subject,
at
similar
sensation
levels.
Saunders
and
Hertzler
(1968)
reported
that
the
click
intensity
DL
for
human
subjects,
at
a
sensation
level
only
5.0
db
less
than
that
used
in
the
present
study,
was
2.9
db.
These
authors
also
noted
that
the
intensity
DL
for
click
stimuli,
in
the
human,
appears
to
be
less
sensitive
than
the
intensity
discrimination
of
either
pure
tones
or
noise.
The
click
DL
in
cat,
similarly,
is
greater
than
previously
re-
ported
pure
tone
intensity
DLs
in
this
species
(Dworkin,
1935,
Rabb
and
Ades,
1946,
Rosen-
zweig,
1946).
Saunders
and
Hertzler
(1968)
noted
that
the
transient
nature
of
the
click
give
it
qualities
that
are
considerably
different
from
noise
or
pure
tone
stimuli.
In
particular,
the
sharp
onset
and
offset
of
the
click,
has
definite
properties
and
the
undesirable
na-
ture
of
these
transients
has
been
recognized
and
controlled
for
in
many
auditory
experi-
ments
by
the
use
of
onset
generators
designed
to
eliminate
this
artifact.
It
appears
that
the
click
intensity
DL
is
greater
than
the
intensity
DL
for
pure
tones
or
noise
and
that
this
rela-
tionship
also
holds
true
for
the
cat.
Moreover,
previous
data
show
that
the
ability
of
cats
to
discriminate
pure
tone
intensity
is
less
than
that
of
man
for
similar
stimuli.
The
present
results
extend
this
observation
to
the
intensity
discrimination
of
clicks.
REFERENCES
Beksy,
G.
von.
A
new
audiometer.
Acta
Oto-Laryn-
gology,
1947,
35,
411-422.
Blough,
D.
S.
The
study
of
animal
sensory
processes
by
operant
methods.
In
W.
K.
Honig
(Ed.),
Operant
behavior:
areas
of
research
and
application.
New
York:
Appleton-Century-Crofts,
1966.
Pp.
345-379.
Clack,
T.
D.
and
Herman,
P.
N.
A
single-lever
psy-
chophysical
adjustment
procedure
for
measuring
auditory
thresholds
in
the
monkey.
Journal
of
Auditory
Research,
1963,
3,
175-183.
Dworkin,
S.
Pitch
and
intensity
discrimination
by
cats.
American
Journal
of
Physiology,
1935,
112,
1-4.
Miller,
G.
A.
Sensitivity
to
changes
in
the
intensity
of
white
noise
and
its
relation
to
masking
and
BEHAVIORAL
DISCRIMINATION
OF
CLICK
INTENSITY
IN
CAT
957
loudness.
Journal
of
the
Acoustical
Society
of
Amer-
ica,
1947,
19,
609-619.
Rabb,
D.
H.
and
Ades,
H.
W.
Cortical
and
midbrain
mediation
of
a
conditioned
discrimination
of
acous-
tic
intensities.
American
Journal
of
Psychology,
1946,
59,
59-83.
Riesz,
R.
R.
Differential
intensity
sensitivity
of
the
ear
for
pure
tones.
Physical
Review,
1928,
31,
867-
875.
Rosenzweig,
M.
Discrimination
of
auditory
intensities
in
the
cat.
American
Journal
of
Psychology,
1946,
59,
127-136.
Saunders,
J.
C.
Evoked
potential
(EP)
correlates
of
a
click
intensity
difference
limen
(DL)
in
cat.
Journal
of
the
Acoustical
Society
of
America,
1969,
45,
293-294
(Abstract).
Saunders,
J.
C.
A
tilt
cage
technique
for
measuring
auditory
evoked
potentials
during
avoidance
con-
ditioning.
Physiology
and
Behavior,
1968,
3,
1003-
1005.
Saunders,
J.
C.
and
Hertzler,
D.
R.
Intensity
difference
limen
for
acoustic
clicks
in
humans.
Paper
presented
at
Psychonomic
Society
meetings,
St.
Louis,
No-
vember,
1968.
Zwislocki,
J.,
Hellman,
R.
P.,
and
Verrillo,
R.
T.
Threshold
of
audibility
for
short
pulses.
Journal
of
the
Acoustical
Society
of
America,
1962,
34,
1648-
1652.
Received
9
January
1969.
... The present performance closely approximated the threshold levels reported by Miller (1970) for a sample of 32 animals. The amount of practice necessary to achieve this level of performance was considerably less than that required to obtain stable thresholds in the cat (Miller, Watson, and Covell, 1963;Saunders, 1969). B. Accumulation and decay of threshold shift in the region of major loss (5.7 k Hz) ...
... Their generalization gradients were symmetrical, and peak response probability occurred when the training stimulus was presented. In a more recent experiment, Saunders (1969) studied the eat's ability to discriminate click intensity. He conditioned cats to make an avoidance response to one level of click intensity and to withhold a response in the presence of another click intensity. ...
Article
Rats were conditioned to respond on the same schedule of reinforcement in the presence of two click stimuli. They consistently responded at higher rates during a 9 clicks/sec stimulus than during a 3 clicks/sec stimulus. However, when the difference between stimuli was increased to 18 clicks/sec vs 3 clicks/sec, the difference between response rates in the two stimuli did not increase. Click frequency was interpreted as a stimulus intensity parameter, but theoretical accounts of stimulus intensity effects do not seem to account for these results.
... dB (Miller, 1947;Jestaed et al., 1977) for ideal conditions of listening over headphones. For free-field conditions and room noise, the JND is on the order of 1-2 dB, based on studies with rodents and cats (Saunders et al., 1987;Saunders, 1969) and estimates using Weber's law (Plack, 2005). ...
Article
The accuracy of a voice vote was addressed by systematically varying group size, individual voter loudness, and words that are typically used to express agreement or disagreement. Five judges rated the loudness of two competing groups in A-B comparison tasks. Acoustic analysis was performed to determine the sound energy level of each word uttered by each group. Results showed that individual voter differences in energy level can grossly alter group loudness and bias the vote. Unless some control is imposed on the sound level of individual voters, it is difficult to establish even a two-thirds majority, much less a simple majority. There is no symmetry in the bias created by unequal sound production of individuals. Soft voices do not bias the group loudness much, but loud voices do. The phonetic balance of the two words chosen (e.g., "yea" and "nay" as opposed to "aye" and "no") seems to be less of an issue.
... The present performance closely approximated the threshold levels reported by Miller (1970) for a sample of 32 animals. The amount of practice necessary to achieve this level of performance was considerably less than that required to obtain stable thresholds in the cat (Miller, Watson, and Covell, 1963;Saunders, 1969). B. Accumulation and decay of threshold shift in the region of major loss (5.7 k Hz) ...
Article
Full-text available
Trained chinchillas were exposed to 6 h of noise followed by 18 h of quiet for nine days. Thresholds (0.5-8.0 kHz) were measured immediately before and after each day's exposure. The decay of threshold shift after the ninth day was followed until stable thresholds were again observed. This procedure was repeated for six levels (57-92 dB SPL) of an octave band noise centered at 4.0 kHz. The threshold shift measured after 4 min of quiet (TS4) appears to reach an asymptotic level (ATS4) after the first or second exposure. ATS4 measured at frequencies exhibiting greatest shift (5.7 kHz), increases with the level of the noise with the same slope (1.7 dB/dB) for the daily 6 h exposures as for nearly continuous exposures. ATS4 is smaller for 6 h than nearly continuous exposures by about 5 dB and this difference can be explained by an equivalent power hypothesis. The decay of threshold shift was nearly complete after 18 h of quiet for the lowest levels of noise, while it was nearly complete only after 3-5 days for the intermediate levels of noise. The decay of threshold shift was never complete and small amounts of permanent threshold shift were observed for the highest levels of noise.
... Behavioral DLs are crucial for comparison, but the author could find no mention of click DLs in Guinea pigs, and found only a single study of the click DL in cats. There, four carefully trained animals produced DLs that ranged from 4.1 to 4.9 dB across animals at a click level equivalent to 44 dB SPL (SL unknown,[28]; Saunders, personal communication). Those DLs are not incompatible with the DLs computed here. ...
Article
Full-text available
The intensity-difference limen (DL) for an acoustic click rises at moderate click levels, a feature called the 'mid-level hump'. It has long been hypothesized that, because a click does not evoke sustained firing in any primary afferent, the DL must therefore originate from the initial burst of synchronized spikes in the eighth nerve. That burst causes the N1 component of the peripheral compound action potential (CAP). It should therefore be possible to predict click DLs from N1 potentials. Here, a Signal Detection model, using a series expansion, was used to derive equations in N1 for the level-dependence of the DL. The first-order equation predicts a dependence on the standard deviation of N1, and an inverse dependence on the rate-of-growth of the mean N1. The second-order equation is more complicated. Both approximations were applied to N1s from the cat. Both produced a mid-level hump; at its peak, the DLs from the second-order approximation were the smaller ones, and were of the same order of magnitude as the empirical DLs. Overall, the computations show that the rate-of-growth of the mean N1, not the standard deviation of N1, determines the hump in the empirical DL.
Chapter
This chapter uses the design and conduct of an auditory detection task to illustrate positive reinforcement operant conditioning methods for domestic cats. Issues of early training are outlined where the investigator plays a critical interactive role with the subject. Automated systems for conducting behavioral testing are summarized. Finally, criteria for evaluating optimal performance and stability of auditory behaviors are discussed. Training and testing strategies presented should prove equally useful for non-auditory sensory experiments.
Article
Full-text available
Avoidance conditioning and the method of limits were used to measure absolute auditory thresholds, masked thresholds, and critical ratios in 4 parakeets. The same procedure was then used to study frequency difference limens in 6 additional animals. The power spectrum and "constancy of intonation" of the parakeet call were also measured and related to the absolute and differential frequency sensitivity. The mechanism of frequency analysis in the parakeet ear was considered in relation to the present results and to the anatomical and functional differences between the avian and mammalian auditory systems.
The relationship between sensory-neural activity and behavioral discriminations of acoustic stimuli were investigated in two experiments. Experiment I compared simultaneously the behavioral detection of 1.0 and 2.0 kc/sec tones of varying intensity with the amplitude of a frequency-following response in the cochlear nucleus. In Experiment II, behavioral thresholds for the detection of a cochlear nucleus electrical pulse were related to threshold levels of auditory cortex evoked responses. The results of both experiments demonstrated a correspondence between the level of neural activity and the behavioral detection of acoustic stimuli. Moreover, the results suggested that simultaneous acquisition of neural and behavioral data were unsuited to an absolute threshold discrimination task.RésuméLa relation entre l'activité des neurones sensoriels et les discriminations comportementales de stimuli acoustiques a été explorée dans deux séries d'expériences. La première compare simultanément la détection comportementale de sons à 1,0 et à 2,0 kc/sec d'intensité variable à l'amplitude de la réponse en fréquence consécutive au niveau du noyau cochléaire. Dans la deuxiéme expérience, les seuils comportementaux de détection d'un influx électrique du noyau cochléaire sont reliés aux niveaux de seuil des réponses évoquéss au niveau du cortex auditif. Les résultats de ces deux séries d'expériences montrent une correspondance entre le niveau d'activité neuronique et la détection comportementale des stimuli acoustiques. Par ailleurs, ces résultats suggèrent que lácquisition simultanée de données nerveuses et comportementales ne permet pas la discrimination absolue d'un seuil.
Article
Trained 4 adult cats to track a differential threshold for click intensity. As Ss performed the discrimination task, click-evoked responses at the cochlear nucleus (CN) and auditory cortex (AC) were recorded. The amplitude of the evoked activity was compared with the intensity difference of the click and the behavioral discrimination. Results suggest different evoked-response functions between the CN and AC for correct or incorrect behavioral discriminations of click intensity. (20 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved).
Article
Full-text available
An intensity DL was determined in cats by using a modified Bekesy tracking procedure. Clicks were continuously presented the subject, one every 400 msec. A discrimination trial occurred when the intensity of alternate clicks was increased. The difference click was designated C1 while the standard was C2. On successive trials the acoustic difference between C1 and C2 was increased or decreased with a correct or incorrect behavioral discrimination. With the standard stimulus arbitrarily set at −25 dB re 1 dyn/cm2, the DL in four subjects averaged 4.5 dB with a standard deviation of 0.7 dB. All subjects had electrodes implanted in the cochlear nucleus (CN) and auditory cortex (AC). The EP's produced by C1 and C2 were computer averaged for every trial, and the microvolt difference between EP1 and EP2 was correlated with the acoustic difference and the behavioral response. The EP's at the CN reflected the acoustic differences regardless of whether a correct or incorrect behavioral discrimination occurred. The ...
Article
The ratio of the minimum perceptible increment in sound intensity to the total intensity, DeltaEE, which is called the differential sensitivity of the ear, was measured as a function of frequency and intensity. Measurements were made over practically the entire range of frequencies and intensities for which the ear is capable of sensation. The method used was that of beating tones, this method giving the simplest transition from one intensity to another. The source of sound was a special moving coil telephone receiver having very little distortion, actuated by alternating currents from vacuum tube oscillators. Observations were made on twelve male observers. Average curves show that at any frequency, DeltaEE is practically constant for intensitites greater than 106 times the threshold intensity; near the auditory threshold DeltaEE increases. Weber's law holds above this intensity, the value of DeltaEE=constant lying between 0.05 and 0.15 depending on the frequency. As a function of frequency DeltaEE is a minimum at about 2500 c.p.s., the minimum being more sharply defined at low sound intensities than it is at high. This frequency corresponds to the region of greatest absolute sensitivity of the ear. Analytical expressions are given [Eqs. (2), (3), (4) and (5)] which represent DeltaEE, within the error of observation, as a function of frequency and intensity. Using these equations it is calculated that at about 1300 c.p.s. the ear can distinguish 370 separate tones between the threshold of audition and the threshold of feeling.
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"Sensitivity to changes in the intensity of a random noise was determined over a wide range of intensities. The just detectable increment in the intensity of the noise is of the same order of magnitude as the just detectable increment in the intensity of pure tones. For intensities more than 30 db above the threshold of hearing for noise the size in decibels of the increment which can be heard 50 per cent of the time is approximately constant (0.41 db)… . Functions which describe intensity discrimination also describe the masking by white noise of pure tones and of speech. It is argued, therefore, that the determination of differential sensitivity to intensity is a special case of the more general masking experiment. The loudness of the noise was also determined, and just noticeable differences are shown to be unequal in subjective magnitude." (PsycINFO Database Record (c) 2012 APA, all rights reserved)
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A tilt cage procedure is described in which cat subjects were trained to make a rocking response. This response introduced a self-imposed restraint so that the cat's position can be maintained in a controlled stimulus field. The resulting reduction in motor activity allows electrophysiological events to be recorded during avoidance conditioning.