what do i need to learn cognitive approach
TRANSCRIPT
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1 J Kavanagh: Pensby High School
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2 J Kavanagh: Pensby High School
Course Content PageNumber
Done Needs more
work
Key Terms:
Definition of the approach
Information processing
Memory
Forgetting
Storage
Retrieval
Research Methods:
Natural, Lab and field experiments
Evaluate experiments in terms of
o Situational and participant variables
o Objectivity
o Reliability
o Validity
o
Experimenter effects
Demand characteristics
Independent (IVs) and Dependent (DVs) variables
Operationalisation of variables
Hypotheses (experimental, null, one and two
tailed)
Repeated measures, matched pairs and
independent groups designs
Order effects
Counterbalancing
Randomisation
Theories of Memory: Describe and evaluate Craik and Lockhearts
(1972) Levels of Processing Framework of Memory
Describe and evaluate one other model/ theory of
memoryAitkinson and Shiffrens (1968) Multi-
Store Model
Theories of Forgetting:
Describe and evaluate Tulvings (1974) Cue
Dependent Theory of forgetting
Describe and evaluate one other theory of
forgettingDisplacement Theory
Studies in detail: Godden and Baddeleys (1975) study of cue
dependency theory
Craik and Tulvings (1975) study of levels of
processing theory
Key Issue:
Is Eyewitness testimony reliable?
Practical:
A laboratory experiment on memory
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Definition of the Approach:
The cognitive approach began in the 1950s, cognitive psychologists argue that the way we perceive and
think determines the way in which we behave.
Cognitive Psychology is about how information is processed in the brain. When information is taken into the
brain through the senses, it is recorded, processed and there is an output. The cognitive approach examines
how this occurs.
According to the cognitive approach, the mind is like a computer, in that it processing information in a linear
logical fashion.
The cognitive approach uses scientific methods such as laboratory experiments.
Key Terms:
Information processing
o This relates to the computer analogy, the brainhas inputs from the senses, processes this
information and outputs it in the form of a
recalled memory or language for example. If
you take the example of crossing a road, the
input is seeing the cars on the road, the
processing is considering how safe it is to cross
and the output in the behaviour either
crossing the road or staying put.
Memory
o Memory is an important cognitive function used to retain and recall information when needed.
Memory is used for relaying events to friends, recalling childhood memories, places, faces and how
to ride a bike etc... Without memory we would have to rely on reflex actions and instinct, memory is
part of what makes us human.
o Transforming sensory information (sights, sounds etc...) into a memory is called encoding.
Forgetting
o Forgetting can occur at many different stages, it can represent a failure of encoding, storage or
retrieval. If we do not pay attention to sensory information it will be quickly forgotten. If we do not
rehearse information it may decay and not be passed into our long-term memory. Information in
our long-term memory may be forgotten because it is not longer available or not longer accessible. Storage
o We have three storage systems, sensory storage, short-term storage and long-term storage (see
multi-store model for more information).
Retrieval
o This is the process of locating and extracting stored memories so that they can be used.
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The Multi-Store Model, Atkinson and Shiffren, 1968
This describes memory as consisting of 3 types of information store:
Information enters SENSORY MEMORY
o This is a buffer for all of the information in the environment that bombards our perceptual system.It is held here for a very brief period
If sensory information is attended to it is stored in SHORT-TERM MEMORY
o This holds around 7 +/- 2 pieces of information for around 18-30 seconds. Information is held mainly
in an acoustic form. Information is forgotten according to the FIFO principle (first in first out).
Rehearsal means it is held here for longer or
If information is rehearsed or practiced it is stored in LONG-TERM MEMORY
o The capacity of LTM is unlimited and information is held mainly in a semantic form. Facts, skills and
events stored together in the order they have been leant.
According to this theory, if information is not rehearsed it is lost or FORGOTTEN.
Evaluation:
It has experimental support. Glanzer and Cunitz (1966) got
participants to remember a list of words. They found the words
from the start and the end of the list were well remembered but
the middle words forgotten. The said this was due to the
primacy and recency effect; the words at the start of the list
(primacy) had been rehearsed and transferred into long-term
memory and the words at the end of the list (recency) were still
in short-term memory.
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There is also evidence from cases studies of patients with brain damage. HM had an operation to remove
part of his temporal lobes to help alleviate his epilepsy. It was found that while his short term memory was
intact and he could remember most things from before his operation, he was unable to form any new long-
term memories. Furthermore, people with Prader-Willi syndrome have normal LTM but poor STM. These
case studies support the idea that memory is separated into STM and LTM.
Gelkopf and Zakai (91) disagreed with FIFO principle, when they presented students with a list of 28 words,
they did not find that words from the beginning of the list were poorly recalled.
The case study of HM shows that the MSM explanation of LTM is too simplistic, as he could not remember
new facts and events but could learn new skills. This supports the argument that LTM should be separated
into semantic, episodic and procedural memory.
* Note there are limitations to case studies using brain damaged patients- damage is not always neat, other parts of
the brain can take over after damage has taken place, hard to generalize from one patient to everyone.
*Note there are limitations to the laboratory experiments of memory, most of the tasks are incredibly artificial and
do not replicate the way learning takes place in real life.
*While the MSM is helpful in helping us understand the separation of memory into different stores, it is widely
acknowledged that the model is far too simplistic.
Craik and Lockhart (1972) Levels of Processing Model
As opposed to Atkinson and Shiffren, Craik and Lockheart did not look at memory as a
series of different stores, but at the ways in which information is processed and how this
affects remembrance. They wanted to understand why it is we remember some things
and not others.
Craik and Lockhart believe that LTM should be defined in terms of how deeply
information has been processed rather than length of storage.
Types of rehearsal:
Type I or maintenance rehearsal means we rehearse the information to preserve it for a short period of time
and this is unlikely to result in a strong memory being established (like remembering a telephone number
long enough to go away and ring it).
Type II or elaborate rehearsal is where information is given meaning, deeper consideration is given to the
information and the memory is more durable.
Information Processing:
We have a central processor which determines how perceptual information is processed. If the information
is distinctive, relevant or requires time or effort to process, it is likely to be processed at a deeper level.
They argued there are 3 LEVELS OF PROCESSING
1. Structural (processing by what things look like) = Shallow processing
2. Phonetic (processing by what things some like)
3. Semantic (processing by what things mean) = Deep processing
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* Depth of processing can be witnessed by Craik and Tulvings (1975) experiment.
Evaluation
There is support from laboratory experiments. Hyde and Jenkins (1971) found that when participants were
asked to do different tasks with the same lists of the words there were different levels of recall. Participants
had to copy the words, cross out the vowels or judge something about the meaning of the words. People
remembered 4 times as many words when judging meaning.
The MSM assumes anything remembered for longer than a minute or so is held in LTM, but this account
does not explain why some memories are strong and some weak. Levels of processing theory does this, so
can better account for the diversity of memories stored.
The model has wide applications; in schools teachers can explain to students that doing something with the
information rather than simply reading it, will lead to a deeper level of processing and will therefore be more
likely to be remembered.
Nyberg et al (2002) scanned participants who were doing a memory experiment, they found greater activity
in the frontal and temporal parts of the brain during semantic processing.
The model is oversimplified. Depth is not the only factor which affects memory e.g. relevance can be
important, as can emotional significance (Reber et al 1994).
The model may be describing, rather than explaining how memory works.
It can only be used to explain improved recall in explicit memory (memory that requires conscious recall), it
does not really affect recall from implicit memory (memory that is recalled automatically).
Morris et al (1977) found that phonetic processing was better than semantic processing for remembering a
list of words. They argued that the nature of the task determines the depth of processing used, rather than
depth determining retention directly.
Deeper processing often takes more time, so it could be the time spent and not the depth of processing thatmeans the information is more likely to be remembered.
Structural
Weak memory trace Strong memory trace
Phonological Semantic
Shallow processing Deep processing
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Tulving (1974) Cue-dependent Theory of Forgetting
Ever tried to remember something when you know the information is in your head somewhere but you cannot
retrieve it, then you remember it when someone gives you a clue? This is known as the tip of the tongue
phenomenon and is the most noticeable experience of cue-dependent forgetting.
There are two main explanations of why we forget: either the information is not available to be remembered
because we have failed to store it or it has decayed from our memory or it is available to be recalled but we
cannot seem to find it.
The cue-dependent theory states that forgetting applied to long-term memory, not to the short-term store.
The theory states that forgetting occurs if the right cues are not available for memory retrieval. This
suggests that memory depends on cues being available.
Tulving claims that there are two events necessary for recall:-
A memory trace - information is laid down and retained in a store as a result of the
original perception of an event
A retrieval cue - information present in the individuals cognitive environment at
the time of retrieval that matches the environment at the time of recall
The encoding specificity principle:
When we encode a new memory we also store information that occurred around it, such as the way we felt
and the place we were in. If we cannot remember, it could be because we are not in a similar situation to
when the memory was originally stored.
Tulving called this the encoding specificity principle and in simple terms it means the greater the similarity
between the encoding event and retrieval event, the greater the likelihood of recalling the original memory.
For example, if we encode a happy childhood memory, we are more likely to remember it when we are
happy again. The mood of happiness acts as a cue to trigger the event from memory. However, if we are ina different state or context, we are less likely to remember, resulting in cue-dependent forgetting.
Cues can be differentiated into:-
Context-dependent - the situation or context is different from that at encoding
State-dependentthe persons state or mood is different from that at encoding
Context-dependent
Context is a powerful cue to aid recall. If we are not in the same situation as when learning, we may not be
able to access the memory easily. This explains why revisiting a place after many years triggers memories ofbeing there.
There are also environmental cues that can aid recall or impair it if missing. Here are some examples of
studies to support this:-
Smith (1985), examined music as a cue to memory and gave 54 participants a list of words to learn and recall
immediately in a quiet environment or with Mozart or jazz playing in the background. Two days later the
pps were asked to recall the words, again in quiet, listening to Mozart or jazz music. This made nine
conditions in which pps recalled with the same or different background noise to the first recall. Forgetting
occurred when the background music was not the same, demonstrating that, without the same music as a
context cue, recall is impaired.
Schab (1990), examined the smell of chocolate as a cue and found it was a strong aid to recall. The results of
this study indicated that if a chocolate smell is present at the time of learning and recalling then the recall
rates were significantly higher (0.21) compared to no smell of chocolate (0.13).
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State-dependent
When we learn information, we also encode details about our emotional and physical state at
the time. If we wish to recall the memory, state cues may not be present, making it
difficult to remember.
Duka et al (2000), carried out a study to illustrate this point by giving 48
participants alcohol or a placebo, prior to a list of 40 word pairs to learn.
Pps were tested in one of four learning-recall conditions: alcohol-alcohol,
alcohol-placebo, placebo-alcohol or placebo-placebo. Duka found thatrecollection of the words was better if the same state for learning was in
place for recall. Without placebo or drug being reinstated as a cue, pps forgot the words.
Evaluation of Cue-dependent Forgetting:
The theory of cue-dependent forgetting cannot be refuted as it would be impossible to too tell whether a
memory is inaccessible or whether it is lost. We can only rely on accounts of experience where we have
recalled the memory later.
The theory has support from real life; it can explain the flooding back of memories you have when you meet
up with an old friend or revisit your primary school.
The theory has experimental support from hundreds of studies. For example, Godden and Baddeley (1975)
found that divers who learnt and recalled words in the same context, on land or under water, recalled 50%
more than divers who learnt and recalled in different contexts. This study supports the theory of cue
dependent forgetting because without the presence of the environment as a context cue the divers were
unable to access the stored word list.
Most of the experiments use artificial tasks. Even though some studies such as Godden & Baddeley (1975)
have been carried out in natural environments, which will improve ecological validity the tasks used in
natural studies usually involve learning lists of words which can still be criticised for lacking experimental
validity.
Although it might be accepted that retrieval cues are necessary for
remembering, Tulving agrees that there is also a memory trace. The theory
may only account for some types of forgetting that occur when words are
being learned. There might be other types of forgetting associated, for
example, with the memory trace.
It is difficult to distinguish between state and context cues in some
circumstances. Music can be a context cue as it is an environmental feature,
but it is also a state cue as music can affect your emotion.
Displacement Theory of Forgetting
The theory that displacementcauses forgetting can be understood by reference to the multi-store model of memory.
The idea is that there is a short-term store where information is held for a short time (up to about 30 secs). It iseither rehearsed there, so that the information goes into the long-term store, or is lost.
The theory of displacement as a reason for forgetting is that the rehearsal loop in the short-term store has a limited
capacity (perhaps 9 items or fewer). If material is being rehearsed in the short term store, it is possible that, before
a bit of information has gone into the long-term store, it could be displaced in the rehearsal loop by a new bit of
material. The old material is lost in other words, it is forgotten.
Evidence for displacement as a theory of forgetting
The ideas of the primacy and recency effects come from the multi-store model of memory:
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The primacy effect is that information learned first is quite well remembered, probably because it has gone
into the long-term store through the rehearsal loop.
The recency effect is that information that is learned last is quite well remembered. Probably because it is
still in the rehearsal loop and so is available for immediate recall.
Information from the middle is not well recalled. This is probably because it did not go from the rehearsal
loop into the long-term store, but was displacedby new material in the loop and was lost, ie forgotten.
This is evidence for the ideal of displacement in the short-term store.
Waugh & Norman (1965) tested this idea. They read a list of letters to participants. After hearing the list, the
participants were told one of the letters and they had to try to remember the subsequent letter. For example, if the
list was B P S T J F A O N and researchers called out T, the participants had to say J. They found that
displacement did seem to occur.
However, Glanzer et al (1967), although they thought that displacement was a factor in forgetting, also thought that
decay caused forgetting. This was because displacement would cause the same degree of forgetting, whatever the
time delay between learning and recall. Therefore displacement alone does not explain forgetting.
Evaluation of displacement theory of forgetting:
The theory fits with the multi-store model of memory and can therefore be linked to this process to help
understand the process. This is because both models suggest a loop where information is rehearsed before
being stored in the long-term store. If there is a loop with limited capacity (the msm model suggested up to
9 items) then it makes sense to say new material displaces material already in the loop. This theory of
forgetting supports two models of memory that are themselves supported by a great deal of evidence. This,
in turn, is support for this theory of forgetting.
It is tested by experiments that are well controlled and therefore, produce information about cause and
effect. The experiments are replicable and can be tested for reliability. Therefore, displacement is tested
scientifically, which is a strength. The theory is difficult to operationalise. What is taken to be displacement could be interference. The
information in the rehearsal loop could be written over, which is displacement. However, it could be that
the incoming new information interferes with the information being rehearsed. This would be interference,
rather than displacement.
It is tested using artificial tasks, such as lists of letters. This means that what is being tested may not be valid
because it is not a real-life task.
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NAME: Godden and Baddeleys (1975) study of cue
dependency theory
AIM:
Godden & Baddeley wanted to study the effect of the environment on recall and the effect of retrieval cues.
The specific aim was to see if there was BETTER recall when the recall environment was the SAME as the
learning environment.
METHOD:
Godden & Baddeley chose divers as their participants for their field experiment. There
were 18 participants in total; 13 male and 5 female. They were all members of a diving club,
who were on a diving holiday in Oban, Scotland.
Two natural environments were chosen and they were clearly different. They chose
underwater as one environment and on land as the other environment.
All the divers had to learn a list of words (36 in total, two or three syllables) either on
land (dry) or underwater (wet). Then they had to recall the words either on land (dry) or
underwater (wet). Therefore there were 4 conditions;
Condition 1 Dry learning and Dry recall (encoding cue present at retrieval)
Condition 2 Dry learning and Wet recall (encoding cue not present at retrieval)
Condition 3 Wet learning and Wet recall (encoding cue present at retrieval)
Condition 4 Wet learning and Dry recall (encoding cue not present at retrieval)
All participants experienced all 4 conditions, so it was a repeated measures design. There were at least 24
hours between conditions.
The hypothesis was that divers would remember more words (forget less) of the learning and recall
environments were the same (either learning and recalling underwater or learning and recalling on land),
than if the learning and recall environments were different (either learning underwater and recalling on land
or learning on land and recalling underwater).
The independent variable (manipulated) was whether the two contexts (environments) are the same or
different. The dependent variable (measured) was how many words are correctly recalled.
The experiment was conducted over 4 days, following a schedule dive to ensure all
participants were in the same wet and cold state. Participants in all conditions were
fully kitted in diving gear (even when learning on land and recalling on land).
Participants being submerged for learning or recall wore breathing apparatus and a
communication device, whilst those on land sat by the edge of the water with
breathing apparatus removed.
Divers were tested two at a time and submerged up to 20 feet underwater and played a tape recording of
the word list through a diving communication device (diver underwater communication (DUC) device). The
recorded words were presented in blocks of 3, with a 4 second interval between each block to ensure the
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noise of the breathing apparatus did not affect the hearing of the words. Each list was presented twice, and
after a 4 minute delay the participants had to write down the words, in any order, in 2 minutes. All
participants used a pencil to write the words, on a weighted clipboard sealed with plastic.
RESULTS:
Percentage/average number of words recalled out of 36 words depending on the learning and recall contexts
Learning environment Recall environment dry Recall environment wet
dry 37 %
13.5 words
24%
8.6 words
wet 23%
8.5 words
32%
11.4 words
The table shows that the percentages were higher when the learning environment and recall environment
were the same (37% and 32%). When the learning environment and recall environment were different, recall
was lower (23% and 24%).
CONCLUSIONS:
The environment can act as a contextual cue. When the cognitive environment at recall is the same as at
encoding, forgetting is less.
EVALUATION:
A main strength of this field experiment is that it did have a number of controls. For example, the timings
between the presentation of words was controlled in all conditions which increases the experiments
reliability.
The situations clearly demonstrate the two different context conditions to test the effect of context cues so
we can argue that the study was a valid test of cue dependency.
There is also support from other studies that support the findings of this experiment. For example Aggleton
and Waskett (1999) tested the effects of context dependency (smell cues) at the Jorvik museum. They found
that smells present at encoding acted as cues and aided the recall of the participants.
It is also possible to argue that the experiment has useful applications for example in the training of divers.
That is, divers should be taught safety information underwater.
However there are a number of ways in which we can challenge the reliability of the study. There were anumber of flaws within the procedure, for example equipment failure may have led to an unreliable
experience for some participants. Although the participants spent the same amount of time underwater the
location differed and so did the time of day when the dives took place. This means the other contextual cues
were not controlled. Other variables which may have affected the results and which were not controlled for
were the level of the divers fitness, noise, weather condition etc.
It could also be argued that the change in environments were so extreme that this is not a normal
occurrence in everyday life, which may mean that the results are not ecologically valid. Furthermore the
experiment was quite artificial because the use of the word lists and that the changes in context were too
extreme to be ecologically valid. On the other hand the participants were divers and therefore were use to
being under water whilst carrying out various tasks.
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It is also possible to argue that the experiment lacks population validity because the participants were all
experienced divers and may not be representative of the general population. There might be something
about divers that makes their responses to cues different to the rest of the population.
NAME: Craik and Tulvings (1975) study of levels of processing theory
AIM:
The aim of this experiment was to test the claims of the levels of processing framework. In particular the
experiment aimed to investigate whether processing words at different levels (structurally, phonetically or
semantically) affected the recall of words
METHOD:
Craik and Tulving reported several variations of this procedure.
In this procedure the 24 participants were tested individually
and were each shown 60 words via a tachistoscope (a devisethat allows the researcher to display words for a very short
and controlled length of time). The words were shown one at
a time for 200 milliseconds.
Before each word was displayed the participants were asked a
question about the word which required a yes/no answer.
Each question related to a particular level of processing.
The first condition involved structural processing, for example,
in which participants were asked if a word displayed was
written in capital letters.
The second condition involved phonetic processing, for example, in which participants were asked if a word
displayed rhymed with another word. The third condition involved semantic processing, for example, in which participants were asked if a word
displayed fitted into a sentence.
The independent variable is therefore the level of processing, that is, structural, phonetic or semantic.
The experiment used a repeated measures design as all participants took part in all three conditions of the
experiment. The experimenters also used counterbalancing as the conditions were run in a variety of orders
to ensure that no one type of processing always occurred first or last.
Participants were then given an unexpected recall task in which they had to recognise the test words from a
word list of 180 words. This list was made up of the original 60 words and a further 120 new words.
The dependent variable is therefore the number of words correctly recognised.
RESULTS:
Semantic processing did lead to a better memory of words. That is participant were more likely to recognise
words from the list if they had been processed at a semantic level. Participants were less likely to remember
words from the list if they had been structurally processed.
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Craik and Tulving also noted that participants did take longer to respond to questions that required a deeper
level of processing
CONCLUSIONS:
Craik and Tulving concluded that the experiment supports the prediction made by the levels of processing
approach that the deeper information is processed (with semantic being the deepest, then phonetic and
then structural being the shallowest) the more likely it is to be remembered.
EVALUATION:
The experiments carried out by Craik and Tulving were very highly controlled. For example they used
standardised procedures and the time for which the words were displayed was controlled by the
tachistoscope so every word was displayed for exactly the same length of time.
Because the study was so well controlled it is easy to replicate the study. This is an advantage because it
improves the reliability. The basic experiment has been replicated several times finding similar results.
The experiment was high in experimental validity due to the counterbalanced repeated measures design
used. Participants are testing their recall in all of the conditions of the independent variable so this makes
comparisons between their performance across conditions fair. The counterbalancing controls for order
effects as participants had to answer the questions for each condition in no set order so it is unlikely that
having to process information in one way would affect how they processed it in other ways.
The variable of depths of processing was also clearly operationalised in the experiment through the way the
questions were asked with each question related to a different type of processing.
It can be argued that although the sample size was small it did consist of a varied mix of participants (males,
females, ages etc) suggesting that generalisation is possible.
There is also supporting evidence from Hyde and Jenkins (1973) which found that when participants carried
out different orienting tasks recall was affected by the depth of processing required by the task. When
participants were asked to judge something about the meaning of the words this led to 51% more recall than
when they were asked to perform non semantic tasks such as having to cross out vowels. However, studies have shown that there are other factors that can affect how well material is remembered.
For example Reber et al (1994) found that emotional content of words can affect the ability to recall. Morris
et al (1977) found that information that is relevant to the individual is often remembered best regardless of
how they were told to process it.
Craik and Tulvings experiment can be criticised for being low in ecological validity. Because the experiment
was laboratory based and required participants to recall a word list it was not like a true to life experience of
how people would normally use their memories. The task required participants to process information under
test conditions which might affect effort. In reality people are not normally asked if a word is written in
upper or lower case and then perform recognition tests so the test is very artificial.
Finally it is worth noting that participants did take longer to answer the semantic type questions so perhaps
their memory was better due to longer processing time rather than type of processing.
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* Note this is a summary, you must revise the information used in class for your Key Issue!
Is Eyewitness Testimony Reliable?
An Eye Witness is someone who witnessed anevent and is later asked to recount the event
from memory. This account is used in a
criminal justice setting and is often the corner-
stone of the prosecution case. Research has
found that juries pay particular attention to
eye witness testimony in reaching a verdict.
Eyewitness testimony refers to an account
given by people of an event they have
witnessed. For example, they may be required
to give a description of a robbery or a road accident someone has seen. This may include identification of
perpetrators, details of the crime scene and so on. Elizabeth Loftus has argued that eye witness testimonies should be treated with caution and demonstrated
through numerous studies that memory could easily be distorted by leading questions.
The Devlin Committee was set up to investigate the use of eye witness testimony in court. It found that
many people have been convicted of serious crimes by eyewitness testimony alone. For example 82% of
suspects chosen from an identification parade were convicted and 74% of cases where eye witness
testimony was the only evidence were judged guilty.
The Devlin Report recommended that the trial judge be required to instruct the jury that it is not safe to
convict on a single eyewitness testimony alone, except in exceptional circumstances or when there is
substantial corroborative evidence.
Whilst there is considerable evidence which supports the findings that eyewitness testimony is unreliable,
not all research supports the findings of this argument. For example, in a study by Yuille and Cutshall (1986)that looked at a real life crime it was found that the reports of the crime were extremely reliable with most
witnesses giving accurate information. When the researchers asked leading questions these had little effect.
Loftus developed the theory called the reconstructive
hypothesis to explain how memory can be distorted and
therefore why we should not trust eyewitness testimonies. She
argues that two kinds of information go into a persons memory
of an event. The first is the information obtained from perceiving
an event, and the second is the other information supplied to us
after the event (e.g. the question containing hit or smashed).
Over time, the information from these two sources may be
integrated in such a way that we are unable to tell from whichsource some specific detail is recalled. All we have is one memory.
Other information that you have learnt during this course may also explain why memory is not always
reliable and be used to improve the reliability of eye witness testimony.
Cue dependent memory can be used to help increase the amount of accurate detail recalled by an eye
witness. Police reconstructions reactivate context cues that were present at encoding to help trigger recall
of the events. By putting the witness back into the context in which the event happened they will recall more
detail. This assumes the original memory is available but not accessible without the right cues.
This may also be true of state cueswitnesses to crimes make be stressed and anxious. If left too long
before being interviewed this state will change possibly affecting their ability to recall. By interviewing the
witness as soon as possible this effect will be minimised. Immediate interview might also help to avoid trace
decay affecting the memory of the event, as if left too long without recalling the event this theory suggeststhat the memory trace will fade away and be unavailable.
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* Note you must revise the summary sheet you completed about the experiment you conducted in class
* Note you must revise using your research methods revision guide all sections for Unit 1. This is some extra
information to aid your understanding of the experimental method and confounding and extraneous variables.
Experiments: produce quantitative data which can be analysed statistically.
There are three main types of experiment laboratory experiments, field experiments and quasi (natural)
experiments.
Laboratory experiments:
A laboratory experiment is an experiment conducted under highly controlled conditions.
A laboratory is any environment where variables can be well controlled. Such environments are usually
artificial but do not have to resemble a science lab at school.
The variable which is being manipulated by the researcher is called the independent variable and the
dependent variable is the change in behaviour measured by the researcher.
All other variables which might affect the results and therefore give us a false set of results are called
confounding variables (also referred to as random variables).
By changing one variable (the independent variable) while measuring another (the dependent variable)
while we control all others, as far as possible, then the experimental method allows us to draw conclusions
with far more certainty than any non-experimental method. If the independent variable is the only thing thatis changed then it must be responsible for any change in the dependent variable.
Evaluation:
Laboratory experiments allow for precise control of variables. The purpose of control is to enable the
experimenter to isolate the one key variable which has been selected (the independent variable), in order to
observe its effect on some other variable (the dependent variable); control is intended to allow us to
conclude that it is the independent variable, and nothing else, which is influencing the dependent variable.
However, it must also be noted that it is not always possible to completely control all variables. There may
be other variables at work which the experimenter is unaware of.
o A confounding variable is a variable which has an unintentional effect on the dependent variable.When carrying out experiments we attempt to control extraneous variables, however there is always
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the possibility that one of these variables is not controlled and if this affects the dependent variable
in a systematic way we call this a confounding variable.
o An extraneous variable is a variable which could effect the dependent variable but which is
controlled so that it does not become a confounding variable.
It is argued that laboratory experiments allow us to make statements about cause and effect, because unlike
non-experimental methods they involve the deliberate manipulation of one variable, while trying to keep all
other variables constant. Sometimes the independent variable is thought of as the cause and the dependent
variable as the effect.
Furthermore, experiments can usually be easily replicated. The experimental method consists ofstandardised procedures and measures which allow it to be easily repeated.
However laboratory experiments are not always typical of real life situations. These types of experiments are
often conducted in strange and contrived environments in which people are asked to perform unusual or
even bizarre tasks. The artificiality of the situation, together with the unnatural things that the participants
may be asked to do, jointly produces a distortion of behaviour. Therefore, it should be difficult to generalise
findings from experiments because they are not usually ecologically valid (true to real life).
A further difficulty with the experimental method is demand characteristics. Demand characteristics are all
the cues which convey to the participant the purpose of the experiment. If a participant knows they are in
an experiment they may seek cues about how they think they are expected to behave.
Another problem with the experimental method concerns ethics. For example, experiments nearly always
involve deceiving participants to some extent and it is important to recognise that there are very many areas
of human life which cannot be studied using the experimental method because it would be simply too
unethical to do so.
Field experiments:
A field experiment is an experiment that is conducted in the field . That is, in a real world situation. In field
experiments the participants are not usually aware that that they are participating in an experiment.
The independent variable is still manipulated like in laboratory experiments.
Evaluation:
Field experiments are usually high in ecological validity and may avoid demand characteristics as the
participants are unaware of the experiment.
However, in field experiments it is much harder to control confounding variables and they are usually time
consuming and expensive to conduct.
In field experiments it is not usually possible to gain informed consent from the participants and it is difficult
to debrief the participants.
Although field experiments do not have such tight control over variables they do have the advantage of
being far less artificial than laboratory experiments.
Quasi or natural experiments:
Quasi experiments are so called because they are not classed as true experiments.
A quasi experiment is where the independent variable is not manipulated by the researcher but occurs
naturally. These experiments are often called natural experiments.
In a true experiment participants are allocated to the conditions of an experiment, usually through random
assignment, however this is not always possible for practical or ethical reasons.
In a quasi experiment the researcher takes advantage of pre-existing conditions such as age, sex or an event
that the researcher has no control over such as a participants occupation.
Evaluation:
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A strength of quasi experiments is that participants are often unaware that they are taking part in an
investigation and they may not be as artificial as laboratory experiments.
However, it is argued that with quasi experiments it is harder to establish causal relationships because the
independent variable is not being directly manipulated by the researcher.
It is worth noting that quasi experiments are very common in psychology because often ethically and
practically they are the only design that can be used.
More about extraneous variables and control:
Extraneous variables are often classified as participant and situational variables.
When carrying out an experiment using an independent measures design it may be possible that participant
differences are a confounding variable. For example if we find out that participants perform better on a test
in a morning than an evening it may be that the participants who took the test in the morning are better at
memory tests. An obvious way of controlling for participant variables is using a repeated measures design.
Furthermore having a larger sample and randomly allocating participants to each condition may reduce
participant variables. It may also be possible to use a matched pairs design where each participant could be
matched with another in terms of their memory performance.
Situational variables are any feature of the experiment which could influence the participants behaviour.
Experimenters attempt to control environmental factors such as noise by ensuring that these are consistent
for both conditions. With a repeated measures design order effects can be controlled for by
counterbalancing.
A way of reducing demand characteristics is to use a single blind technique whereby participants are not
aware of the aims of the experiment. Furthermore, to reduce investigator or experimenter bias a double
blind technique could be employed whereby both the participant and the researcher carrying out the
experiment are unaware of the aim of the experiment.
Control groups are often used in experiments. This is a group which does not receive the manipulation of
the independent variable and can be used for comparison with the experimental group or groups.