of six trials (e.g., sequence of R R L R R R is successful
but L R L R R R is not because over string of 6 trials
only 4 were correct; Figure 4).
b. In Figure 4, fish learned the task at trial 15. We call this
reaching criterion, the standard by which something is
judged or decided. In other words, fish has successfully
accomplished task as defined. A 5/6 criterion is common in learning studies and, in terms relevant to the
students’ experience, is a grade of “B” (83% correct).
Upon reaching criterion, place the fish back into starting
block. Repeat above procedure until fish reaches criterion,
except now correct side is LEFT arm. This is termed a
reversal task and measures cognitive flexibility. In reversal learning, the individual first learns to choose right in a spatial
discrimination problem and then must choose left. Such
reversals can be difficult and directly measure cognitive deficits,
especially when testing for sensitivity to environmental
chemicals (Evans et al., 1994).
7. Entire procedure is done on Day 1 as a training method, on
Days 2 and 3 for learning, and on Day 8 for memory.
8. When all trials are completed, drain the water, rinse T-maze
and all gates with distilled water, and dry overnight. If students
find that they can test more than one fish per day, fresh dechlorinated water must be used for the second fish. During the trials, fish may excrete alarm substances that affect behaviors of
Optional Test – Double Reversal Task
To fully test cognitive flexibility, scientists may use the more challenging double reversal task (e.g., Saili et al., 2012). In this test,
the animal first learns the task, which is followed by a reversal.
However, the animal is then asked to reverse its choice back to
the original correct side. Such double reversals usually require
more time (30 trials/session) than a single class period allows, so
such a test would be limited to those students who are conducting
the experiment on their own time.
It is best to display results comparing the control to the experimental
variable using a graph. Many students have difficulty constructing
and interpreting this presentation of data (Berg & Phillips, 1994;
Berg & Smith, 1994). Importantly, with this skill students discover
that different graphs can explain different aspects of the learning
and memory process.
1. Number of trials to reach criterion for first and second task:
How long does it take for fish to learn (Figure 5A, B, D)?
2. First correct trial: How long does it take for fish to discover
the correct side?
3. Longest string of correct trials (maximum = 5; Figure 5C):
How consistent is fish in choosing correct side?
4. Longest string of incorrect trials, the Perseveration Index
(maximum = 20), where perseveration is the tendency to
continue the same sequence of behaviors even though conditions have changed and require new or modified behaviors
( i.e., get “stuck” on a wrong choice; Cañas et al., 2006). Perseveration is often associated with brain damage.
5. Number of trials needed to successfully reverse task (trials
between end of successful completion of first task and beginning of string of trials ending in successful completion of second task): How easy is it for fish to display cognitive flexibility?
6. Number of fish successfully completing tasks 1 and 2: What
percentage of sample population shows cognitive flexibility?
It is important for students to understand that because testing
is done at discreet time points and data are not continuous, they
should use a bar graph. Line graphs incorrectly imply behavioral
changes during the day. Using the bar graph, the x-axis represents
Time (days) or Specific Task (Training, Testing, Reversal) and the
y-axis represents the dependent variable. Bars of both the control
and experimental variable should be placed on the same graph
for easier comparisons.
The correct statistical test to analyze data within and between
test days is a repeated-measures analysis of variance (ANOVA)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Fish
5 of 6 correct and meets criterion of learning
Figure 4. Sample group data sheet.