Casey

Question 1

Define delayed gratification

Answer 1

Resistance to temptation of an immediate pleasure in the hope of obtaining valuable reward in the long term

Question 2

Define conitive control

Answer 2

Ability to suppress copeting innappropriate thoughts or actions in favour of appropriate ones

Question 3

What is the function of cognitive control

Answer 3

Aids delayed gratification mauy be linked to teh inferior frontal gyrus loacted in the pre frontal cortex.

Question 4

Aim

Answer 4

To investiaget teh extent to whch teh ability ot resist temptation at preschool age affected the same partciapnts in adulthood. Control over impulses nd sensitivty to scoial cues at the behavioural and neural level were examied

Question 5

Mthod

Answer 5

Longitudinal tracking the same partcipants from age 4 until 40s

Question 6

Design

Answer 6

2 Natural Quasi Experiments as the IV naturally occuring

Question 7

Partciapnts

Answer 7

Ppts selected from the original cohort of 562 children who did the marshmallow test (1960s.)
-155 of these completed self-control scales in their 20s (1993), then 135 of these when in their 30s (2003)
.-117 of the 135 individuals were contacted in relation to participating in this study.
-In Experiment 1 there were 32 high delayers (12 m, 20 f) and 27 low delayers (11 m, 16 f).
- In exepreiemtn 2, 15 high delayers and 11 low delayers

Question 8

Procedure of experimnt 1

Answer 8

Completed in own homes with pre programmed laptop
Instructions to either press a buton (go) r withhold from pressing (no go)
Cool included the presentation fo afecs. One sex was go
Partcipants given instructions ot reposnd quickly
Each face appeared from 500 milliseconds followed by a one second interval
160 trials used in a random order.
The hot task varied by facial expressions only

Question 9

Procedure of experiment 2

Answer 9

partciapnts scanned with fmri whilst completing a hot version fo go/no go task
an electronic reponse pad was used ot record reposnses to facial stimuli an dreaction times
48 trials presented during each run
Each face appeared for 500 milliseconds followed by intervals ranging from 2 seconds to 14.5 seconds.
Reserachers colleced imaging data for 26 no go trials adn 70 go trials per facial expression

Question 10

Results of experiment 1

Answer 10

Both groups highly accurate in their correct reposnses to go trails in both cool and hot conditions. (99.8 and 99.5%)
Low delayers were slightly more likely to repond mistakenly in the no go trials and perfromed slightly worse than high delayer in the hot version fo the task
Low delayers identified at 4 years of age showed greater difficulty suppressing their reposnes to happy fces than highdelayer

Question 11

Results in experiemnt 2

Answer 11

No significant difference between the two delay groups on reaction times in correct go trials.
-Accuracy across both group were very high for go trials.
-Low delayers had higher false-alarm rates in the no-go trials
-LD had reduced activity in Inferior frontal gyrus compared to HD during gotrials (The right inferior gyrus appeared to be critical in withholding reponses with ld showing reduced actvity in this in the no go trials)
-High levels of activity in the Ventral striatum for LD compared to HD (mostly during the happy no-go trials for LD)
The ventral striatum is the reward realted region

Question 12

Samplein exepriemnt 11

Answer 12

32 hd

27 ld

Question 13

sample in experiment 2

Answer 13

15 hd

1 ld

Question 14

Conclusion

Answer 14

Resistance to temptation is a relatively stable characteristc of an indivdual over itme
Cogntie control can be strongly influenced by contenxtual factors (e.g hot cues in alluring situations)
Ventral frontalstriatal circuitry supports resiatnce to temptation, with a combination of lowered actvity in their inferior frontal gyrus and increased actvity in the ventral striatum in ld

Question 15

Validity: Strengths

Answer 15

he study was highly internally valid due to the high use of controls and standardisation in both experiments. The controlled extraneous variables allowed conclusions to be drawn about the independent variable of being a low or high delayer age 4 causing the dependent variable of behaviour in impulse control tasks.

Question 16

Validity wekanesses

Answer 16

As the first experiment occured in participant’s homes, there could be extraneous variables present which were not controlled and individual differences between participants based on their own home environments.
This could reduce internal validity as one of these factors could have caused the dependent variable, rather than the independent variable.
Moreover, as the study was a quasi experiment there was a naturally occuring IV and this could not be manipulated. Low delayers may have had more difficulty paying attention when doing the tasks and this may have affected their performancerather than their impulse control. They may also have personality traits such as being more assertive or aggressive and this could cause them to press go on no-go stimuli.

Question 17

Demand Characteristics

Answer 17

Demand characteristics and social desirability are unlikely to have affected results as behaviour remained constant over the 40 years.

Question 18

What extraneous varibales were controlled adn how

Answer 18

Extraneous variables which were controlled were the equipment in the experiments. In the first experiment, there was a carefully standardised programme used on the laptops used by participants to present stimuli and record responses. It was therefore higgly accurate and standardised because the software used for the go/no-go tasks allowed reactions and their times to be recorded with high accuracy, thus avoiding human error. The second experiment occurred under laboratory conditions and therefore any extraneous variables e.g. noise were controlled. This experiment also gained highly valid data as the fMRI scanner directly observed empirical evidence of brain activity. These were highly objective and therefore allowed conclusions to be drawn about brain activity and being a low/high delayer affecting behaviour in impulse control tasks. This provided the study with high internal validity.

Question 19

Any uncontrolled extraneous vairbales

Answer 19

As experiment 1 took place in participant’s own homes, there may be uncontrolled extraneous variables depending on the home environments of participants e.g. if anyone was in the room with them when they did the task, what time they did the task, background noise, other distractions etc. Therefore there is a possible risk of extraneous variables affecting the performance of participants. There may also be participant variables and this is more of a problem in quasi experiments as participants cannot be given a condition randomly as the conditions of being a high or low delayer are naturally occuring.

Question 20

Ecological validity

Answer 20

Weaknesses: The ecological validity of this study can be considered to be low. The nature of the go/no-go tasks was artificial and in real life, we would not normally encounter and respond to facial expressions in this way. Moreover, it cannot be said that the facial expressions were even measuring impulse control in the participants and perhaps a different stimuli would have been more effective and appealing. Themundane and experimental realism of experiment 1 is low as participants would never do a go/no-go task in everyday life. The fMRI scanning done in experiment 2 is also low in mundane realism as it is an uncomfortable experience which isn’t something one does as an everyday activity. The scanner may have impacted on how participants responded to the faces shown in the impulse control tasks. Real life social interactions are much more complex than the tasks presented in this study and our brains may behave differently in these situations compared to the way they behave under artificial conditions. Therefore, the study is ungeneralisable to everyday life and is very low in ecological validity.

Question 21

Internal reliability: Strengths

Answer 21

Strengths: Casey’s study showed that from 4 years to 40 years of age, participants remained consistent in being a low or high delayer so findings from measures within the study are consistent.Moreover, Casey demonstrated that there were consistent results between experiment 1 and 2 in terms of the percentage of errors made betweenthe high and low delayers. Low delayers had slightly more errors in both experiments so this was consistent. We can say the internal reliability of the study was high

Question 22

Internal relaibility: Weaknesses

Answer 22

Weaknesses: It is difficult to recreate Casey’s study from 4 years to 40 years as it is longitudinal and this would be expensive to replicate so it is hard to measure whether the results would be consistent again between both experiments if the study was repeated.

Question 23

External reliability: Weaknesses

Answer 23

Weaknesses: Due to the longitudinal nature of the study, it is difficult to replicate in order to check the reliability of the study. This would require starting with 4 year olds and following them into their 40s and would be neither time or cost effective. Therefore, we cannot prove the reliability of Casey’s findings easily.

Question 24

External reliability: Strengths

Answer 24

Strengths: The experiments are highly standardised so if replicated, results are likely to be similar. Experiment 2 occurs in a laboratory setting and was therefore highly controlled so the method in the study is reliable. The fMRI scanner being used to measure activity in the ventral striatum and the right interior frontal gyrus meant if replicated using the same equipment, the experiment would likely lead to consistent results. Therefore we can say Casey’s study is fairly reliable in terms of the actual experiments.

Question 25

Quanititative data strengths

Answer 25

The use of quantitative data in this study through reaction times, errors made and brain activity of these participants is good as it means there can be direct comparisons made between both conditions. This showed us that young children who were low delayers in the original gratification delay task still showed less cognitive control in alluring situations as adults. The use of quantitative data is also good as it is easy to summarise e.g. errors into percentage errors and the data can also be put into graphical form. The data also makes the study easier to replicate in order to check the reliability of its findings.

Question 26

Quantiative data weaknesses

Answer 26

The use of just quantitative data ignores qualitative data such as the analysis of cognitive strategies individual participants had when in the impulse control tasks or even everydaylife. This would be useful for practical applications when teaching low delayers to be high delayers. This is a weakness as researchers could observe the differences between low and high delayers but didn’t obtain information on why these differences in their brains and behaviour were present

Question 27

Sampling bias

Answer 27

Although the sample was initially large with 564 participants, it is limited to individuals who attended a single nursery during a specific time period of the late 1960s and early 1970s. This causes the findings of the study to be geographically limited and they may only be representative of people from similar family backgrounds. Moreover, not all the children from the original task took part and within the conditions of either being a high or low delayer, there were much smaller numbers of participants. This may link into ethnocentrism as it is possible that impulse control is nurtured differently in different cultural societies and therefore there may be differences across cultures regarding impulse control. This could be due to capitalist countries such as the United States having more low delayers due to the politics of the country and children being raised in a mindset of being told to get what they want. A consumerist country could also put temptingstimuli in people’s paths more often than in other cultures whereas a poorer country may have more high delayers as children are not in circumstances where they can even get food or clean water everyday. Therefore, ethnocentrism could play a part in this study as a lack of self control cannot be assumed to be a universal human trait. However, ethnocentrism is unlikely to have affected results as brain functions are said to be universal and species specific and therefore unaffected by culture.

Question 28

POpualtion

Answer 28

Initially, there was a large pool of 564 participants in the study, they all came from one nursery during a specific time. Therefore, the sample is limited geographically and may only represent peopledrawn from similar social backgrounds. There were also small numbers in the conditions, especially experiment 2 which had 27 participants. This split into 16 high delayers and 11 low delayers, and of the 11 low delayers only 4 were female. It cannot be said that 4 females can generalise to all female low delayers. The sample is simply too small for generalisations to be made. This means we cannot assume that the brains of all low and high delayers would be the same as the 27 participants who were tested in the fMRI scanner. The issue of attrition in the sample is important in Casey’s study as there was a very large drop in participantsacross the longitudinal study. From the 564 participants at age 4, there was only 59 in the first experiment and this dropped to 27 in the second experiment. Although 117 participants had been invited to participate in the first experiment, approximately half accepted the offer. This may be simply because of lack of time or effort and the initial attrition could be due to the whereabouts of participants simply being lost over the years. However, this attrition means the sample reduced in size and may not even be generalisable to the original sample. This is because those participants who continue to do the experiments may have a different personality than those who do not; this may be similar to volunteer samples who are seen as more obedient typically. It can be said that population validity is low as the sample is too small and biased to generalise to the target population.