Transcript Young & Wells (2008)

The Effects of Vicarious Learning with Experienced Rats
Jessie Young and Lyndsey Wells
Randolph College
Lynchburg, VA 24503
Introduction
Quadrant Preference
A one-sample t-test was conducted for the two experienced rats to determine
whether preference for the correct quadrant was exhibited. A quadrant
preference greater than .25 indicated a good memory.
Both rats showed a poor preference for the correct quadrant, t(1) = 2.636, p =
.231 (two-tailed) with scores of .09 and .20 compared to the model rat who had
a .26.
Paired-Sampled T-test were run in order to see if the quadrant preferences were
significantly different in each rat. The only significant difference found was
between the SW and SE quadrants, t(2)=4.865, p=.04. However, a significant
difference was almost found between the NW and NE quadrants, t(2)=4.09,
p=.055.
Time Spent in Each Quadrant
80
70
60
Time in Seconds
Vicarious learning is defined as “a change in behavior due to the
experience of observing a model” (Chance, 2006). Various animal studies have been
done in the past vicarious operant conditioning. Most results showed the animals did
greatly benefit from observing the model. The animals that observed, performed the
task in less time as compared to animals that did not watch the model (Chance,
2006). For example, Herbert & Harsh (1944) conducted a study using a turntable
where one cat learned to spin the table in order to receive food while four other cats
observed. The cats who observed outperformed the model cat all around.
Past research has found that vicarious operant conditioning has been
successful in various animals including monkeys, cats, and humans. However, we
have not read many studies using rats. We have also not read any studies where they
had used vicarious learning with subjects that had previously learned to do the task a
different way. In order to test this, we used rats that had previously learned to
complete the task in a different location. Due to the majority of past research
showing vicarious learning to be successful, we hypothesize the experienced rats
will have a high quadrant preference for the SE quadrant after observing the model
being trained in the sand maze to dig for FL in the SE quadrant.
Results
Model Rat
50
Discussion
40
Observer 1
30
Observer 2
Method
Subjects
The subjects were 6-month-old, male Long-Evans rats (N=3). Our experienced group
consisted of 2 rats who had previously learned to dig in the NW quadrant, and our
model was an inexperienced rat that learned to dig in the SE quadrant. Rats were
reduced to and maintained at 85% of their free-feeding weights one week prior to
experimentation and water was available ad libitum.
Apparatus
A plastic pool that was 36 inches wide by 6 inches deep was filled with a sand and
crushed Froot Loops (FL) cereal mixture. This sand maze was 2 inches deep with
approximately 11 ounces of FL crushed and mixed with 100 pounds of play sand and
was elevated of the ground by 36 inches (Chandler & Wetzel, 2006). The
observational towers were created using lab stools with empty cages stacked on top.
The subjects were sitting approximately 1 ½ feet above the sand maze and placed as
close as possible to the western edges of the maze.
Procedure
Before training, the two experienced rats were set in a way so they could observe the
inexperienced rat’s shaping trials in the sand maze, as seen in Figure 1. The model rat
was taught to dig in the south east quadrant of the same maze using 10 shaping trials,
(4 on day one, 4 on day two, and 2 on day three). The FL were always buried at a
shallow level in order to insure he will always find the FL. During the trials, 10 FL
halves were placed in the SE quadrant. The rat was then placed in the maze using
random location placement for each trial (N, E, S, W). Latency to dig and number of
FL consumed were recorded for each trial. Each trial ended when the rat consumed 6
FL. Between each trial, the sand was mixed and the walls were wiped down in order
to extinguish intra-maze cues.
On the day of Testing, one at a time, each rat was placed into the sand maze starting
from the south, for three minutes, while being recorded with a video camera. Testing
was used as an extinction trial, meaning there were no FL in the maze. After each had
finished their testing, the videos were used to measure the amount of time spend in
each quadrant and quadrant preferences were calculated.
20
10
0
NW
NE
SW
Quadrant Location
SE
The experiences rats did not learn to dig in the SE quadrant by using vicarious
learning. This is probably due to the fact that the rats did not seem to be paying
attention to the model rat.
The majority of time spend by all three rats were in the western quadrants. This
may be because the rats cages were located on that side. This seemed to be very
distracting for the rats when they were in the maze.
In addition, the model rat’s behavior was not ideal. He seemed to be more
interested in the other rats and running around the maze instead of eating the FL.
This could cause confusion for the rats who are observing.
The experienced rats showed a higher preference for the NW quadrant. This
may be due to their previous training.
Observer's learning history is very important and because they had previously
learned to dig in the NW quadrant perhaps a blocking situation occurred. It may
be more difficult to establish a new quadrant preference if the previously learned
quadrant was strong enough to block out the new.
During the testing period, the rats were left in the room. For the model rat, the
cages served as visual cues, however, for the experienced rats, this may have
served as a larger distraction.
In the future, it would be beneficial to test a larger amount of rats, as well as
have a control group consisting of rats that did not get to observe a model. It
would also be interesting to compare rats who have previous experience to those
who do not. Also, we would like to see the use of a different apparatus because
perhaps the sand maze was a little challenging to observe.
References
Chance, P. (2006). Learning and behavior: Active learning edition
(5th ed.) Belmont, CA: Thomson/Wadsworth.
Chandler & Wetzel (2006). Acquisition and retention in rats: Comparing
olfactory and visual cues as facilitators of learning. Poster
presented at Randolph-Macon Woman’s College, Lynchburg, VA.
Gotthard, G.H. (2008). Experimental Psychology: Learning
Laboratory Lab Manual. Randolph College.
Figure 1