EXPERIMENT NO.

General Problem: On memory and forgetting.

Specific Problem: Experimentally determine the effect of proactive inhibition on the capacity of
memorization of the subject through visual presentation of stimuli.

Basic Concept:

Memory refers to the mental faculty that is used to acquire, store, retain and later retrieve information. Memory
is both an influence on and result of perception, attention and learning. Cognitive psychologist, Margaret W.
Matlin defined memory as "the process retaining information over time." According to Ryburn (1956),
memory is "the power that we have to store our experiences and to bring them into the field of consciousness,
some time after the experiences have occurred." However, memory is not just the revival of past experiences
because it is a complex process which involves several factors like learning, retention, recall and recognition. It
comprises systems that can hold information for periods of time, ranging from fractions of a second to a
lifetime, and systems that have a very limited storage capacity to those with vast storage capacity.

Memory involves three interrelated processes: encoding, storage, and retrieval.

•Encoding is the process where the information that comes into our memory system (from sensory input) is
changed into a form that the system can cope with, so that it can be stored.
•Storage is concerned with the nature of memory stores, i.e., where the information is stored, how long the
memory lasts for (duration), how much can be stored at any time (capacity) and what kind of information is
held.
•Retrieval (or recall, or recognition) is the calling back of stored information in response to some cue for use in
a process or activity.
In experiments, it is generally preferred to break up the process into the learning period, the retaining period and
the testing period. In the learning period, registration and learning takes place by sensory input and
transforming it into a neural coded form. In the retaining period, the coded information is actually put into
memory. Finally, in the testing period, the reproduction of the stored and coded information takes place by
recall and recognition. In the testing period, the amount of information recalled is determined by the amount of
information learnt(encoded), retained(stored) and successfully retrieved. Learning and its facets, thus, affect the
retention and retrieval - the capacity of memorization.

When it comes to measuring the amount of information retained, a problem arises because meaningful words
have many pre-established associations for the human adults. To counter this problem Hermann Ebbinghaus
(1885) simplified and standardized his experiments by the invention of nonsense syllables, which are
meaningless words that do not have associations with other information in the memory.

Problems can occur at any stage of the process, leading to anything from forgetfulness to amnesia. Forgetting
refers to the loss of information that was previously encoded and stored in memory. Munn (1967) defined
forgetting as "the loss, permanent or temporary, of the ability to recall or recognise something learned earlier."
According to Drever (1952), "Forgetting means failure at any time to recall an experience, when attempting to
do so, or to perform action previously learned." There are many factors that can contribute to forgetting. One of
today's best-known memory researchers, Elizabeth Loftus, has identified four major reasons why people forget:
retrieval failure, interference, failure to store, and motivated forgetting. Numerous processes and theories have
been proposed throughout the long history of study to account for forgetting, including the trace decay theory,
the interference theory and the repression theory.

According to the interference theory, forgetting takes place because all memories interfere with the ability to
recall other memories. Forgetting occurs because of interference from other memories (Baddeley, 1999). The
more similar to or more events are to one another, the more likely interference will occur. Under this theory
transience, which refers to the general deterioration of a specific memory over time, is said to take place. Memory
can be disrupted by what we have previously learnt, or by what we are learning now (or will learn in future).
There are two basic types of interference that can occur - retroactive inhibition and proactive inhibition.

Proactive (pro means forward) inhibition occurs when the previously learned information makes it difficult to
form new memories. In general, it is when we have preconceived notions about certain situations and events and
apply them to the current situations and events. Learning a new phone number or a new locker combination,
for example, might be more difficult because the memories of our old phone number or locker combination
interfere with the new information.

Proactive inhibition refers to the tendency of previously learned material to hinder subsequent learning. It is the
tendency of previously learned material to hinder subsequent retrieval of newer memories of newly learned
material. Of the two types of interference, proactive inhibition is considered the less problematic type of
interference compared to retroactive inhibition. It has been hypothesized that forgetting working memories
would be non-existent if not for proactive interference. It has been found that if the items or pairs to be learned
are conceptually related to one another, then proactive interference has a greater effect.

Experimental designs for demonstrating proactive inhibition differ from those used for showing retroactive
inhibition in that the experimental group learns task B before, instead of after, task A. Whereas B was a task that
was interpolated between the learning and the recall of task A in the retroactive inhibition study, B is a task that
precedes the learning of task A in the proactive inhibition study. To evaluate the effects on the experimental
subjects of their having learned B prior to A, the control people are instructed to relax during the time the
experimental group is learning B.

Delos Wickens discovered proactive interference using a list of items to be remembered. As expected, recall was
hampered by increasing the number of items in a given list. Proactive interference also affected learning when
dealing with multiple lists. Benton J. Underwood designed an experiment to discover the decremental effects
on retention resulting from the prior learning of several lists (proactive inhibition). The results of these
experiments present a number of perplexing theoretical problems because there was an increase in inhibition due
to successive interpolations.

Proactive interference has shown an effect during the learning phase in terms of stimuli at the acquisition and
retrieval with behavioural terms for humans or found by Castro, Ortega and Matute. With 106 participants,
they investigated two main questions: one, if two cues are learned as predictors of the same outcome (one after
the other), would the second cue cum association be rewarded? And secondly, once the second association is
fully learned will there still be an effect on subsequent trials? The research, as predicted showed retardation and
impairment in associations due to the effect of proactive interference.

The aim of this study is to experimentally determine the effect of proactive inhibition on the capacity of
memorization of the subject through visual presentation of stimuli.

Preliminaries:

Name of the subject: Medini Dumka

Age of the subject: 18
Sex of the subject: Female
Education of the subject: UG-1
Language known to subject: English, Hindi
Condition of the subject: Fresh and cooperative
Date of the experiment: 12th March, 2021
Time of the experiment: 3:40-4:50
 Materials Required:

•Lists of nonsense syllables

•Strips of paper
•Stop-watch
•Screen
•Paper window
•Pen, pencil, eraser, scale

Plan of the Experiment:

a.Experimental Design:

Independent Variable (IV)

Proactive inhibition

Levels of IV

a. Absence of interpolated task between learning and recall of original task

b. Presence of interpolated task between learning and recall of original task

Dependent Variable (DV)

Capacity of memorization

b.Plan of the Experiment- General Framework:

Preparatory Phase

✓Visual presentation of a list of 10 nonsense syllables to find out the memory span of the subject (by
the method of retained number)
 ✓Length of the list = memory span×3

Rest for 5 minutes

Experimental Condition

✓List A will be presented visually till 100% criterion of mastery

✓Post Criterion Task (PCT) will be taken
✓Time taken will be noted down
✓List B be presented visually till 100% criterion of mastery
✓PCT of List B will be taken
✓Recall of List B will be taken

Rest for 10 minutes

Control Condition

✓Non-interfering filler task will be employed (duration will be the time taken to learn List A)
✓List C will be presented visually till 100% criterion of mastery
✓Post Criterion Task (PCT) will be taken
✓Recall of List C will be taken

c.Plan of the Experiment – Specific Framework:

Stimulus Response Response Measure

Visual Stimuli:
 Lists of nonsense syllables •Percentage of recall in each trial

Set 1: •Accuracy of reproduction in

•List A is presented for a number •The subject memorizes the list PCT
of trials until 100% learning and reproduces it mechanically
occurs. The time taken is recorded. (writes it down) in correct order. •Accuracy of reproduction of List
•List B is presented immediately •After 100% learning, the subject B and C in recall after the PCT,
after PCT of List A. recalls and reproduces the list (A) that is, percentage of proactive
•List B is presented for a number for PCT. inhibition.
of trials until 100% learning •The subject memorizes List B and
occurs. reproduces it mechanically (writes
it down) in correct order.
•After 100% learning, the subject
recalls and reproduces List B for
PCT.
•The subject again recalls and
reproduces List B.

Set 2:
•The subject is engaged in •The subject doodles or draws
non-interfering filler task (time lines as a non-interfering filler task
period will be the time taken to •The subject memorizes the list
learn List A). and reproduces it mechanically
•List C is presented for a number (writes it down) in correct order.
of trials until 100% learning •After 100% learning, the subject
occurs. recalls and reproduces the list for a
PCT.
•The subject recalls and
reproduces list C once again.

d.Controlling Techniques of Extraneous Variables:

Extraneous Variables Controlling Techniques

Subject-relevant variable:
 Age, sex, educational level, individual differences Kept constant (since N=1)
Motivation, attention Uniform and repeated instructions were given
throughout

Stimulus-relevant variable:
Length of the list Kept constant
Difficulty level of the list Kept uniform
Duration of presentation of one syllable and gap Kept constant at 2 seconds
between presentation of two syllables

Situation-relevant variable:
Noise Minimized
Illumination Kept constant
Temperature Kept constant

Sequence-relevant variable:
Practice effect and fatigue effect A rest pause of 10 minutes is provided between the
two sets
Formation of association between different syllables No syllable is repeated in a list or in a different list

Instructions:

For immediate memory span

“Please sit comfortably and be very attentive. I shall show you some meaningless syllables one at a time through
the paper window. After I have finished showing the nonsense syllables to you, you have to write down those
syllables in correct order on a piece of paper provided by me.”

For experimental condition

“Please sit comfortably, relax and be very attentive. I will present to you a list of meaningless words. Each time
you will have to memorize the list and reproduce it correctly in serial order. You will be shown the list
continuously until you have learnt the list completely. After you have completely learnt the list, you will have to
recall it and write it down correctly in serial order from your memory without seeing the list. Immediately after
that you will be shown another list of meaningless words and the similar procedure will be followed. But this
time, after you have learnt the list, you will be asked to recall the list, in the correct order, from your memory,
without seeing the list, twice. Please report to me immediately if you have any difficulty.”
For control condition

“Please sit comfortably, relax and be very attentive. I will be engaging in some drawing (doodling/drawing lines)
for some time period. You will start doing that when I ask you to start and will stop it when I ask you to do so.
After that I will present to you a list of meaningless words. Each time you will have to memorize the list and
reproduce it correctly in serial order. You will be shown the list continuously until you have learnt the list
completely. After you have completely learnt the list, you will have to recall it and write it down correctly, in
serial order, from your memory, without seeing the list, twice. Please report to me immediately if you have any
difficulty.”

“After the experiment is over, you will have to give me a written account of your feelings and experiences during
the experiment.”

Precautions:

The following precautions are maintained while conducting the experiment:

a. The paper window should be made accurately so that the subject can see each syllable distinctively
b. Presentation of syllable will be one at a time
c. The screen should be placed in front of the subject so that the subject cannot see the list beforehand
d. While preparing the list an adequate gap between two syllables need to be maintained.
e. An equal time interval of 2 seconds between two nonsense syllables should be maintained while
presenting the list.
f. Each syllable is exposed for 2 seconds to the subject
g. The experiment should be conducted in a well illuminated, calm and quiet atmosphere
h. Rest of 10 min should be provided to the subject after each set of the experiment
i. Non-interfering task (doodling/drawing lines) will be employed during the rest period before the start
of List C for specified time duration.
j. Time taken to learn List A should be carefully noted down.

Rules for Preparing Nonsense Syllables:

a. Each syllable is made by three letters with one vowel in between two consonants (CVC method).
b. Syllables should be written in capital letters.
c. Syllables should be meaningless so that the subject is unable to make any association.
 d. The initial consonant of a syllable is not identical with the final consonant of the same syllable of the
list.
e. No two consecutive syllables in the list should have the same initial consonant or the same vowel.
f. The last consonant of any syllable should not be the same as the first consonant of the next syllable.
g. The order of consonant and vowel should be avoided
h. The vowels are placed at random.
i. W, X, Y, Z, and Q should be avoided from the list.
j. Either C/K or G/J should not be used in the same syllable.
k. H should not be used at the end of any syllable.
l. There should not be any repetition and rhythmic presentation in the list.

Procedure:

Rapport was established with the subject and necessary instructions were provided.

The immediate memory span of the subject was found out first. The subject was shown a list containing 10
nonsense syllables and was asked to reproduce it in serial order. The number of syllables recalled correctly is the
memory span of the subject. Length of each list was taken as thrice of the memory span.

After providing 5 minute rest to the subject, List A was presented to the subject till 100% learning occurred.
PCT was taken immediately. The time taken to learn List A was noted down. Immediately, the subject was
presented with List B till 100% learning occurred. Then, PCT was taken followed by recall of List B.

After providing sufficient rest to subject, the subject was asked to engage in some doodling or drawing lines on a
piece of paper for some specific time duration. The duration was the time taken to learn list A. Then, the subject
was presented with list C till 100% learning occurred. PCT was taken followed by recall of list C.

Finally, the data was calculated to find out the percentage of proactive inhibition. The findings were represented
graphically and interpreted.

Report of the Subject:

In this experiment, I was asked to memorize lists of meaningless words. At first, I found it very difficult to
memorise those meaningless words. I followed all the instructions and tried to memorise the lists. There were
two phases. In the first phase, I had to memorize two lists consecutively. On the other hand, there was a
substantial gap between the first phase and the second phase so I found memorising the list a bit easier in the
second phase.
 Data and Calculations:

Table 1 showing determination of memory span of the subject:

Nonsense Syllables Subject's Reproduction

BUR BUR ✔️
COJ KOJ ❌
NEF NEF ✔️
JAS JEB ❌
VUR VUR ✔️
REG FUZ ❌
KIB RIB ❌
FAC

PEJ FEJ ❌
MIB MIB ✔️
Number of correct reproduction = 4
Memory span of the subject = 4
Length of the list = (4×3) = 12

Table 2 showing data of list A (which is the interfering task):

Nonsense Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Trial 6 PCT

Syllables

✔️ ✔️ ✔️ ✔️ ✔️ ✔️
HOJ HOJ HOJ HOJ HOJ HOJ HOJ
 ❌ ✔️ ✔️ ✔️ ✔️ ✔️
VAB WEB VAB VAB VAB VAB VAB

❌ ❌ ❌ ✔️ ✔️ ✔️
TOG GOC GOJ GOJ TOG TOG TOG

✔️ ✔️ ✔️ ✔️ ✔️ ✔️
KUS KUS KUS KUS KUS KUS KUS

❌ ✔️ ✔️ ✔️ ✔️ ✔️
MIF DAK MIF MIF MIF MIF MIF

❌ ❌ ❌ ✔️ ✔️ ✔️
BEP MIF VEB VAS BEP BEP BEP

❌ ❌ ❌ ✔️ ✔️ ✔️
GAK VEB PAC BAF GAK GAK GAK

❌ ❌ ❌ ❌ ✔️ ✔️ ✔️
PIS MIF TER KUS TIR PIS PIS PIS

❌ ❌ ✔️ ❌
FUV VAS FUB FUV FUK

❌ ✔️ ✔️ ❌
TER GAF TER TER TAR

❌ ❌ ❌ ✔️ ✔️
NUV VIF NOV MUD NUV NUV

❌ ✔️ ❌ ✔️ ✔️
HIC KUB HIC NIS HIC HIC

Number of
Correct 0 2 4 5 9 12 10
Reproducti
on

Percentage
of Correct 0% 16.7% 33.3% 41.7% 75% 100% 83.3%
Reproducti
on

Table 3 showing data of experimental condition (List B):

Nonsense Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 PCT Recall
Syllables

✔️ ❌ ✔️ ✔️ ✔️ ✔️ ✔️
LEP LEP LAP LEP LEP LEP LEP LEP

✔️ ❌ ✔️ ✔️ ✔️ ✔️ ✔️
NIV NIV NIB NIV NIV NIV NIV NIV

✔️ ✔️ ✔️ ✔️ ✔️ ✔️ ✔️
KOR KOR KOR KOR KOR KOR KOR KOR

✔️ ✔️ ✔️ ✔️ ✔️ ✔️ ✔️
LIM LIM LIM LIM LIM LIM LIM LIM

❌ ❌ ❌ ✔️ ✔️ ❌ ❌
CED SED NIB SED CED CED SED SED

❌ ✔️ ✔️ ✔️ ✔️ ✔️
SOR COR SOR SOR SOR SOR SOR

❌ ✔️ ✔️ ✔️ ✔️ ❌
DAJ LAB DAJ DAJ DAJ DAJ TAJ

❌ ✔️ ✔️ ❌ ❌
VIS VIZ VIS VIS VIZ VIZ

✔️ ✔️ ✔️ ✔️ ✔️
BEF BEF BEF BEF BEF BEF

✔️ ✔️ ✔️ ❌
GOB GOB GOB GOB GUB

✔️ ✔️ ✔️ ✔️
PUJ PUJ PUJ PUJ PUJ

❌ ✔️ ✔️ ✔️
VAD VAP VAD VAD VAD

Number
of 4 4 7 9 12 10 8
Correct
Reproduc
tion

Percentag
e of
 Correct 33.3% 33.3% 58.3% 75% 100% 83.3% 66.7%
Reproduc
tion

Table 4 showing data of the control condition (List C):

Rest Nonsense Trial 1 Trial 2 Trial 3 Trial 4 PCT Recall

Syllables

The subject MOF MOF ✔️ MOF ✔️ MOF ✔️ MOF ✔️ MOF ✔️

JIV ✔️ JIV ✔️ JIV ✔️ JIV ✔️ ✔️
was
engaged in JIV JIV

SUG ✔️ SUG ✔️ SUG ✔️ SUG ✔️

some

✔️
SUG SUG
non-interfe
ring filler
task for the FOM FOM ✔️ FOM ✔️ FOM ✔️ FOM ✔️
time taken
to learn list REK ❌ DEK ✔️ DEK ✔️
❌
DEK TEK
A, that is,

FUV ❌ RUB ❌
14 minutes.

✔️ ✔️
RUV RUV RUV

HON HON ✔️ HON ✔️ HON ✔️

FID FID ✔️ FID ✔️ FID ✔️

❌ ✔️ LUP ✔️ LUP ✔️
❌ ✔️
LUP RUV SOD LUP LUP

VAF FED ❌ VAF ✔️ VAF ✔️ VAF ✔️ VAF ✔️ VAF ✔️

KUN LUP ❌ KUN ✔️ KUN ✔️ KUN ✔️ KUN ✔️ KUN ✔️

ROF VAF ❌ RUK ❌ ROF ✔️ ROF ✔️ ROF ✔️ ROF ✔️

Number
of Correct 0 5 8 12 11 11
Reproduct
ion

Percentage
 of Correct 0% 41.7% 66.7% 100% 91.7% 91.7%
Reproduct
ion

Calculation of proactive inhibition:

Formula: (C-E÷C)×100

[where, C= number of correct recall in the control condition and E= number of correct recall in the
experimental condition]

⸫ Proactive inhibition
= {(11-8)/11} ×100
= (3/11)×100
= 27.27%

Table 5 showing comparison between the experimental condition and control condition and the percentage of
proactive inhibition:

Forgetting
Condition Percentage of Proactive
Correct Recall Due to time gap Due to time gap Inhibition
(Delayed Recall) and proaction

Control 91.7% 8.3% - -

Condition

Experimental 66.7% - 33.3% 27.27%

Condition

Graph:
 Interpretation:

In this experiment, an attempt was made to determine the effect of proactive inhibition on the memorization
capacity of the subject.

From the comparative chart, it is observed that in the experimental condition, the percentage of correct recall
(delayed recall when the subject has previously learned the list A, which acts as an interfering task, before
learning the List B) is 66.7% , and forgetting (due to time gap and proaction) is 33.3% . In the control condition,
the percentage of correct recall (delayed recall before which the subject was engaged in a non-interfering task) is
91.7% , and forgetting (due to time gap) is 8.3% . From the appropriate calculations, the computed percentage of
proactive inhibition is found to be 27.27% .

Comparing the two percentages of correct recall, it may be said that in this experiment, there is a little amount of
proactive inhibition because the percentage of correct recall was lower in the experimental condition, where the
subject had previously learned a list of nonsense syllables (list A), which acts as an interfering task, as compared
to the control condition, where the subject was involved in a non-interfering task during the retention interval.
This suggests that in the experimental condition, learning the list A interferes with the subject's ability to recall
list B, while in the control condition, where the subject performs a non-interfering task like doodling (which
ensures that the subject's mind does not wander, thus decreasing the chances of forgetting due to any other
cognitive processes like thinking, etc.), the percentage of correct recall is greater.

Whitely (1927) found that compared to a control

group, any interpolated information hindered later recall. The participants who were presented with material
related to their lists showed the greatest hindrance as measured by percent correct and percent error in all
temporal conditions. This helps to explain the findings of the present experiment because the present subject
was asked to memorize two lists of nonsense syllables back-to-back which makes the two tasks quite related to
one another and the subject found it a bit difficult to recall the new list due to interference from the previous
list. As a result, proactive inhibition takes place.

Proactive interference, while not as strong as retroactive interference has still been found in many experiments
and is found to cause retardation and impairment in associations due to the effect of proactive interference.

Conclusion:

It may thus be concluded that for the present subject, in the present experiment, a small amount of proactive
inhibition was present when the subject had to learn two lists of nonsense syllables consecutively i.e. when the
subject was asked to learn a list prior to learning another list. This shows that here, for the present subject,
learning a material before interferes or inhibits the retention of the newly learnt material. Therefore, it can be
said that proactive inhibition had a slightly detrimental effect on the capacity of memorization of the subject as
there was a decrease in the percentage of correct recall.