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EVALUATION SHEET:

Study title & authors:

Casey et al. (2011) Study of Delayed Gratification Area/perspective:

Assumptions of this area/perspective:

Biological Psychology

• • •

Behaviour is influenced by biological factors e.g. the brain, genetics, hormones etc. The scientific method is the most appropriate to use - scientific, controlled lab experiments using scientific equipment. The focus is on nature explanations rather than nurture

. Key theme

Regions of the brain

Background

Research has shown that there are individual differences in our capacity to resist temptation. This was tested by Shoda and Rodriguez (1989) who measured how long young children could resist immediate reward e.g cookie in order to receive a better but delayed reward e.g two cookies but later on. Psychologists believe we use cognitive control to create strategies to delay gratification and avoid immediately acting on impulse. Explanations for this are using 'cooling' strategies by focusing on practical features of a desirable object e.g. food rather than the rewarding aspects of it. A study conducted by Metcalfe and Mischel (1999) found that there are 'cool' systems in our brain which are linked to cognitive control and 'hot' systems in our brain which is related to emotion and desires. Previous research on children resisting temptation was also done by Metcalfe and Mischel in 1972. They put marshmallows in front of 4 year old children and told them the researcher would leave and they could eat one marshmallow immediately or eat two when the resesarcher returned. These same children were tested every 10 years so the study is longitudinal and Casey's study focuses on these people at age 40. It was proved that children who were unable to resist temptation at age 4 were still unable to do this in their 20s and 30s.

note any relevant theory/previous studies that informed this research

Aim

To test whether delay of gratification in childhood predicts impulse self-control abilities in adulthood.

Method

Experiment 1:

If an experiment – • Design • IV • DV

Method: Experiment 1 was a behavioural task which tested whether individuals who were less able to delay gratification as children would show less impulse control in suppressing responses to 'hot' cues in relation to 'cool' cues as adults.

If not an expt give full details

Design:

Also include: • Procedure • Materials • Sample Who was the sample? Sampling technique?

The study is described as longitudinal as it studied the same participants over a period of 40 years. The research method was a quasi experiment as there was a naturally occuring IV of being a high delayer or a low delayer at the age of four. The dependent variable was the behaviour of participants on the impulse control task and this was measured through their reaction times and accuracy recorded by the pre-programmed laptop. Sample: The sample was drawn from the initial sample of 562 pupils from Stanford's Bing Nursery School who participated in Metcalfe and Mischel's study at age four in the late 1960s and early 70s. From this sample, 155 completed self control scales in their 20s, and then 135 of these completed the scales in their 30s. From these people, 117 had scores either below or above average in terms of gratification delay and they were contacted. 59 agreed to participate in experiment 1. There was 23 males and 36 females who were split into 32 high delayers and 27 low delayers/ Procedure: The experiment took place in participant's own homes with pre-programmed laptops. Participants read on screen instructions which told them to respond as quickly and accurately as they could. It also indicated what the go and no-go stimuli were. They completed two versions of a go/no-go task. These tasks involved participants pressing a button as a go or withholding themselves from pressing it as a no-go. These tasks were split into 'hot' and 'cool' versions. The cool tasks included a male and female with neutral expressions being presented as stimulus and participants having to press the button depending on the gender of the face so one gender was a go stimulus and the other was a no-go. These faces were drawn from the NimStim set of facial expressions. The hot and cold versions of the tasks differed in the use of happy or neutral/fearful expressions rather than in gender.

Experiment 2: Method: Researchers used fMRI scanners to examine if neural activity linked to delay of gratification in a

task requiring responses to happy or fearful facial expressions. Design: As there were two experiments the study can be argued as both independent and repeated measures design. Experiment 2 was still a quasi experiment with the naturally occuring IV of being a high or low delayer at age 4 and the dependent variable was the behaviour of participants measured through the fMRI scanners. Sample: 27 participants agreed to do the second experiment out of the 59 who took part in the first. There were 13 males and 14 females split into 15 high delayers and 11 low delayers. One male participant's results were excluded in this experiment due to poor performance on the behavioural task. Procedure: Participants were scanned with a fMRI scanner whilst completing a 'hot' version of the go/no-go task similar to that which was used in the first experiment. This experiment occured in a laboratory. The set up meant the task could be viewed via a rear projection screen. An electronic response pad was used to record responses to facial stimuli and reaction times There were 48 trials per run (35 go trials and 18 no go trials). Each face was presented for 500 milliseconds followed by intervals ranging from 2 to 14.5 seconds. Results

Experiment 1:

-quantitative

Quantitative: Both groups were very accurate in go tasks in both 'hot' and 'cool' conditions. 99.8% were correct in cool tasks and 99.5% in hot tasks. Low delayers were found to be slightly more likely to have false alarms (press the button when it was a no-go and therefore respond mistakenly) than high delayers in the 'hot' task. Low delayers identified at age four showed greater difficulty suppressing their responses to happy faces than high delayers.

or/ &

qualitative

Experiment 2:

Conclusions

Quantitative: There was no significant difference between both delay groups on reaction times in correct go trials. Accuracy rates were very high across both groups in go trials and low delayers had higher false alarm rates in no-go trials (14.5%). The right interior frontal gyrus was found to be asssociated with witholding responses as there was increased activity found here for high delayers in comparison to low delayers. There were high levels of activity in the ventral striatum ( a region related to rewards) for low delayers compared to high delayers. This was most prominent during happy no-go trials for low delayers. 1. Resistance to temptation is a stable characteristic of an individual over time. 2. Cognitive control can be strongly influenced by contextual factors e.g hot cues in alluring situations. 3. Ventral frontostriatal activity is linked to resistance to temptation along with increased activity in the ventral striatum in low delayers. There is lowered activity in the right interior frontal gyrus for these low delayers.

A distinguishing feature of this study (something which makes it unique-eg, it uses a pilot study or new technology etc)

Methodological Evaluation issues Internal validity Can include: a) Are demand characteristics likely to have affected the results? (i.e guessing the hyp AND altering behaviour) b) Is social desirability likely to have affected the results? (i.e altering

Internal Validity: Strengths: The 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. Weaknesses: 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 performance rather than their impulse control. They may also have personality traits such as being more assertive or

behaviour to present yourself in a positive light, esp in self-report or observation)

aggressive and this could cause them to press go on no-go stimuli.

c) Which extraneous variables were controlled and how?

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.

d) Any uncontrolled EVs?

Ecological validity

Can results be generalised to everyday life? Consider mundane realism & experimental realism

Reliability

Internal – are findings from measures within the study consistent? If an observation used, what was the inter-rater reliability? External – if replicated are results likely to be similar (consider: standardisation, controls, use of objective measures, quantitative data)

Type of data used: Quantitative/qualitative

Population validity – sample and sampling technique Any sampling bias – explain (eg prone to DCs;

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

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. Ecological Validity: 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. The mundane 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. Internal Reliability: 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. 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. External Reliability: 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. 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. Quantitative Data: Strengths: 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. Weaknessses: 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 everyday life. 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. Sampling Bias: 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

ethnocentric etc) Population validity – can results be generalised beyond this sample to the target population? Explain/justify

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 tempting stimuli 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. Population Validity: 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 people drawn 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 participants across 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.

Any other methodological issues? How this study links to: • The area: (PEET - relate to the key concepts and assumptions) One of the asssumptions of the area of biological psychology is that behaviour can be explained in terms of biology e.g. the brain, genetics, hormones etc which can have a direct influence on behaviour. This is seen in Casey's study of delayed gratification as he looks at participants who have a lot and not very much cognitive control. He classes these individuals as high or low delayers, with high delayers having more cognitive control in repressing desires and delaying gratification. Casey focused on this ability and found it remained constant throughout the lives of participants. Casey focused on the lymbic system, which is also known as a 'hot' system and is related to rewards and desires. The ventral striatum is located in this area of the brain and in his second experiment, Casey found there was more activity in this region of the brain for low delayers. High delayers were found to have higher amounts of brain activity in the right interior frontal gyrus, located in the pre-frontal cortex and associated with being a 'cool' system. The fMRI scanner measured this brain activity whilst participants were doing go/no-go tasks and therefore, Casey found the effect of the brain on behaviour. He therefore reduced gratification behaviour to a biological factor and so h...