Student book answers Chapter 9 Sensory, short-term & long-term memory: the multi-store

modelPages 160–183

Review 9.11 What are the three key processes involved in memory? Explain what happens in each process.

The three processes involved in memory are:

• encoding – the process of converting information into a form that can be stored in memory

• storage – the process of keeping information in the brain so that it can be accessed for use at a later time

• retrieval – the process of getting information back from our memory storage for use.

2 Why is the computer analogy useful for explaining these processes?

Information in memory must be encoded and stored so that it may be retrieved for use at a later time. This is the same way a computer works. Information is typed (encoded) and then stored (for example, on a hard drive) and can be retrieved at a later time (opening a file).

3 Why is this analogy also inadequate?

The brain does not store a memory like an object in one place. Each memory is spread out over a huge population of cells throughout different regions of our brain. Storage is also a dynamic process whereby human memories change over time and – again unlike a computer hard drive – human memories are rough copies rather than exact replicas of information.

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Review 9.21 Draw a labelled diagram to illustrate your understanding of Atkinson–Shiffrin’s multi-store model of

memory.

Sensory memory

Brief memory store for incoming sensory information; unlimited capacity; sensory store for each sense

Information attended to is transferred to STM

↓STM

Limited store of actively conscious memory Information to be stored long term is transferred o LTM

↓LTM

Virtually unlimited and permanent store of information

Information can be retrieved back into STM for use

2 What limitation does a computer hard drive have that the human long-term memory does not?

A hard drive has a limited capacity whereas long-term memory does not.

Investigate 9.1Try the following activities.

• Shut your eyes and try to describe what after-image remains. It is likely that you will be unable to describe all of it because it has faded faster than you have the time to remember.

• When at home, use a torch or a sparkler in the dark: wave it around in circular movements. You will notice an after-image in circles of light in the dark atmosphere.

• Hold a pencil loosely between your thumb and index finger and shake it. The pencil will appear to be floppy because of the after-image it leaves on these sensory receptors in the retinas of your eyes.

No answer required

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Investigate 9.2Write a report about Sperling’s study of iconic memory. Answer the following questions:

1 Write the three experimental hypotheses.

• Subjects exposed to brief visual images using a tachistoscope will be able to store them in iconic memory for a brief duration for recall.

• Subjects exposed to symbols for 1/20 second using a tachistoscope will be able to recall a limited number.

• The longer the delay between presentation of symbols, the more symbols will be forgotten.

2 Name the independent and dependent variables.

• Independent variable: sensory images (symbols) flashed on screen using tachistoscope

• Dependent variable: recall of symbols

3 How was the dependent variable operationalised?

The dependent variable was operationalised to the mean number of symbols recalled.

4 What was the experimental design for this study?

The experimental design used was a repeated measures design.

5 Identify one limitation and one advantage of using this experimental design.

• Limitation of repeated measures: practice effect (or fatigue/boredom)

• Advantage of repeated measures: participant variables controlled (same participants for each part of the experiment)

6 Were there any potential confounding variables?

Potential confounding variables: participants did not fully understand the instructions or correctly remember the instructions

7 How might the encoding and retrieval for iconic memory be affected if Sperling’s participants were shown pictures instead of symbols? To answer his question, consider the amount of time it takes to identify and name a picture compared to a symbol.

If Sperling’s subjects were shown pictures instead of symbols, the results are likely to have been quite different. It may have taken more time to identify and name a picture, hence reduced the number of items recalled before the image began to decay. Symbols are faster to identify.

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Review 9.31 Outline the function of sensory memory.

Sensory memory prevents us from being overwhelmed by the huge amounts of incoming sensory information.

2 What happens to information that is not attended to in sensory memory?

Information not attended to in sensory memory is lost (not transferred to short-term memory).

3 Explain the difference between iconic and echoic memory.

Echoic memory: auditory images stored in raw form in inner ear. Iconic memory: visual images stored in raw form in the eyes.

4 What is the capacity and duration of iconic and echoic memory?

Echoic memory: virtually unlimited capacity, duration 3–4 seconds. Iconic memory: virtually unlimited capacity, duration 0.3 seconds.

Investigate 9.31 No answer required

2 One limitation is that short-term memory is influenced by how long it takes to say a word or sound. For example, the letter ‘a’ is quicker to say than the letter ‘w’. Similarly, short-term memory capacity is reduced when people try to remember complex visual patterns because they have to retain so much detail in each pattern. Work with a partner to design your own experiment, using words rather than letters or numbers. You can use the internet for research. Remember to think about the number of syllables in each word. Include the following:

• an aim for the experiment

• an experimental hypothesis

• the independent and dependent variables

• results presented in a table (you may also include a graph)

• a conclusion for your experiment.

You do not need to write a formal report. Present your work as a Word document.

Student responses will vary.

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Review 9.41 How does sensory memory differ from short-term memory?

In sensory memory, stimulus energy is stored in its raw form, but in short-term memory it is encoded. Sensory memory has a very large capacity (visual – briefly retain the whole scene), while short-term memory has a very limited capacity (5 to 9 items).

2 What function does short-term memory play in our ability to remember things?

Short-term memory holds material for long enough so that elaborative rehearsal can encode it into long-term memory.

3 As short-term memory has a limited duration and capacity, what method can be used to increase its efficiency?

Maintenance rehearsal (duration) and chunking (capacity)

Investigate 9.4Work with a partner and follow the instructions below. You might be quite surprised by the results!

1 Remember these numbers in order: 0963157208.

2 Sit on your hands while you answer the following questions:

• Do you turn your front-door key clockwise or anticlockwise when entering your house?

• Do you rotate a tap clockwise or anticlockwise to turn it off?

• How do you use a knife and fork? (Remember to use words only.)

• How do you use chopsticks? (Remember to use words only.)

3 What does the image below mean?

4 What was the name of your Grade 1 school teacher?

5 What was the name of the horse that came fifth in last year’s Melbourne Cup?

6 Describe the front cover of this book without looking at it. How much can you recall?

7 Recite the national anthem out loud without singing the melody.

8 Name the highest mountain in Australia.

9 Cover question 1 above and write the numbers in the exact order as presented.

No answer required.

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Review 9.51 Outline two key differences between short-term memory and long-term memory.

• Short-term memory: limited capacity, limited duration

• Long-term memory: virtually unlimited capacity and duration

2 How is information stored in long-term memory?

In semantic networks

3 Draw a diagram to show our long-term memory stores (procedural, declarative, explicit and implicit).

4 Explain what procedural memories are and provide an example.

Procedural memory involves knowing how to do things – yet we might still find it hard to describe how to do them. For example, how to ride a bike.

5 Outline what declarative memories are and how they differ from procedural memories.

Declarative memory involves memory for facts, events and general knowledge. It generally refers to information associated with learning for school, reading, mathematics and higher order thinking, which is associated with intelligence. It includes semantic and episodic memory. Semantic memory is memory for

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facts, worldly knowledge or general knowledge. Episodic memory refers to memories of particular events and is often autobiographical, such as birthdays, your first day of school or your first romantic kiss. Declarative memories are the ‘knowing what’ and procedural are the ‘knowing how’ memories.

Investigate 9.51 What was the aim of the researchers in the case study?

The researchers aimed to find out if subjects had different levels of activation in the hippocampus for navigational tasks as compared to other memory tasks.

2 Write a simple hypothesis for this study.

A hypothesis could be: London cab drivers will have greater activation of the hippocampus when completing a navigation task.

3 Were there any physiological changes to the hippocampus? Explain.

There were physiological changes to the hippocampus if there was greater activation. This process would have been achieved by greater neuron activity.

4 Can the researchers conclude that changes in the taxi drivers’ hippocampus are caused by the memorisation of maps?

No, researchers cannot conclude that changes to the hippocampus are caused by memorising maps, because it is impossible to know whether the changes were caused by memorising maps or by some other unrelated activity. They can only show whether a relationship exists. This is because this study was a ‘correlational study’, which intends to find out how much two variables are related (e.g. is there a relationship between hippocampus size and navigational ability?). Whereas an experimental study aims to find the relationship between an independent variable and the dependent variable by manipulating the IV to find the effect on the DV (e.g. testing subjects with different sized hippocampi [IV] to see the effect on their navigational ability [DV]).

5 What were the researchers able to conclude about this particular experiment?

Researchers were able to conclude that for London taxi drivers there was a relationship between greater hippocampal activation and navigational tasks.

Review 9.61 What structures of the human brain are involved in memory?

The three key brain structures involved in memory formation are the hippocampus, the temporal lobe and the amygdala.

2 Where are the key parts of the temporal lobes for memory located? What do they include?

The temporal lobe plays a key role in the consolidation of declarative memory. Key parts of the temporal lobe for memory are located in the medial (middle) temporal lobe. They include the hippocampus and amygdala.

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3 Summarise the role of the hippocampus in memory.

The hippocampus is active during slow-wave sleep, when it is thought that memories are processed. Research has shown that performance on a task continued to improve if the subjects had sleep.

4 Summarise the role of the amygdala in memory.

The amygdala is associated with fear and aggression, and is related to the formation of emotional memory. The amygdala has an important role in the regulation of emotions, so it enhances the memory of an event (declarative memory). It activates the hippocampus and therefore the consolidation of the declarative memories.

5 Summarise the role of the cerebellum in memory.

The cerebellum has a role in the memory of how to perform a motor skill; it works with the motor cortex of the frontal lobes.

Test your understanding

Multiple choice

1 D; 2 B; 3 A; 4 C; 5 D; 6 D; 7 A; 8 C; 9 C; 10 A

Short answer

11 Name and describe two structures of the brain that are involved in memory.

• Hippocampus: responsible for the consolidation of declarative memories; transfers information to other parts of cortex for LTM storage

• Amygdala: involved in non-declarative emotional memories

12 The hippocampus functions as a part of the brain that permanently stores new memory. However, memories are transferred to other parts of the brain for permanent storage in long-term memory.

13 People with damage to the amygdala are likely to be incapable of fear or other emotional forms of conditioning.

14 Describe the Atkinson–Shiffrin’s multi-store model of memory, using an example to illustrate your answer.

Atkinson and Shiffrin’s multi-store model of memory describes three stores of memory that are separate but function simultaneously to create our ability to encode, store and retrieve information. Sensory memory is a very brief memory store (like a computer’s buffer). Information enters this register and may then be transferred to the short-term memory if the person pays attention to it. Short-term memory is a limited store of actively conscious memory (like the computer’s random access memory [RAM]). Information is then transferred to the long-term memory if it has been encoded. Long-term memory can be compared with a computer hard drive. However, this store of information has a virtually limitless capacity. It needs retrieval to bring it back into conscious awareness.

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15 Describe the difference in capacity of sensory, short-term and long-term memory.

Sensory memory has a brief duration and an unlimited capacity. It relates to the five senses, including iconic memory for sight and echoic memory for sound. Short-term memory has a limited capacity and duration. Long-term memory is thought to have an unlimited capacity and an unlimited duration.

16 What is maintenance rehearsal and what kind of situation might it be used for?

To retain information in our short-term memory, we use a process called maintenance rehearsal. If you say over and over (either aloud or sub-vocally in your head) something that you want to keep in your immediate awareness, then you may also increase the likelihood of this information being moved into your long-term memory.

17 What is the difference between explicit and implicit memory?

Explicit memory is the conscious retrieval of memory. This includes recall and recognition. Implicit memory is unconscious; that is, it does not require intentional, deliberate recall.

18 Compare the function of semantic memory and episodic memory.

Episodic memories are personalised memories or events and semantic memories are memories of facts or knowledge.

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