Casey et al (Neural Correlates of Delay of Gratification)

Question 1

Background of casey?

Answer 1

Background:
A study by Eigsti (marashmellow) showed that performance on delay of
gratification task in childhood predicted the efficiency of
cognitive control tasks as young adults. (same individuals used)

Question 2

Aim of Casey?

Answer 2

Aim:
Assess whether delay of gratification in childhood predicts
impulse control abilities and sensitivity to alluring or social
cues at the behavioural and neutral level when participants
were in their 40s.

Question 3

Research methods of casey?

Answer 3

Research methods:
Quasi experiment (participants taken from longitudinal study)
Data- quantitative and qualitative

Question 4

Participants used in casey?

Answer 4

Participants:
- All 562 participants selected from original marshmallow test
(1960s-1970s)
- 155/562 completed self-control scales in their 20s (1993)
- 135/155 completed it again in 30s (2003)
- 177/135 contacted in relation to participating in this study.
EXP1: 32 high delayers (12m, 20f) and 27 low (11m, 16f)
EXP2: 27 (13m, 14f) of the 59 who participated in EXP1 agreed to
be part of the functional neuroimaging study. 15 high delayers
(5m, 10f) and 11 low (7 m, 4f)

Question 5

EXP1? produrces and results of casey?

Answer 5

EXP1:
Procedure:
- Participants were given a computer pre-programmed with ‘hot’
and ‘cool’ impulse control tasks to complete at home.
- Their tasks were called ‘Go/No-go’ tasks in which they were
instructed to press a button (go) or not press a button (no-go) with
a target ‘go’ stimulus before each round.
- There were ‘cool’ and ‘hot’ versions of the tasks that included the
presentation of the faces with neutral/ fearful expressions (cool)
and
happy expressions (hot).

Results:
- Both groups were highly accurate in correct responses to the go
trails in both the ‘cool’ and ‘hot’ condition. (99.8% and 99.5%
correct respectively).
- Low delayers were slightly more likely to respond mistakenly in
the no-go. trials and were slightly worse on the ‘hot’ version of the
task.
- Low delayers at 4 years old showed the same difficulty with
suppressing impulse control at age 40.

Question 6

Procedures and results for EXP2? in casey.

Answer 6

EXP2:

Procedure:
-Ppts were scanned with a fMRI (functional magnetic resonance
imaging scanner) while completing a similar impulse control task to
experiment 1
-48 trials presented per run (35 go, 13 no-go)

Results:
-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.
-High levels of activity in the Ventral striatum for LD compared to HD
(mostly during the happy no-go trials for LD)

Question 7

Conclusions? in casey

Answer 7

Conclusions:

-Resistance to temptation is a relatively stable characteristic of an individual over time.

-The capacity to resist temptation (cognitive control) can be strongly influenced by contextual factors.

-Individuals at the age of 4 years who have difficulty delaying gratification have more difficulty as adults in suppressing responses to positive social cues than those who don’t.

-Ability to resist temptation is supported by neural networks in the brain: low delayers have lowered activity in the inferior frontal gyrus and increased activity in the ventral striatum

Question 8

Evaluation in casey?

Answer 8

Evaluation:

Sampling Bias – initially drawn from a large pool of 562 ppts, this sample is limited to individuals who attended the same nursery within a certain time period. Geographically limited and may only represent people from similar backgrounds. The numbers of ppts decreased as the study went on over time.

Ecological validity – Low ecological validity because the nature of the go/no-go tasks are artificial and different from normal responses to facial expressions. Genuine social interactions are much more complex.

Internal Validity - High internal validity, there was no reason ppts wouldn’t try their best. Ppts were fully aware of their tasks. For experiment 2, there is no way the ppts could influence the results of the brain scans.

Reliability – Lab experiment so it is quite reliable with standardized procedure. Very scientific results (especially the fMRI scans). Highly likely that they would get same results if repeated.

Practical application – Provides further understanding about localisation of neural functions for tasks involving rewards and resisting temptation. Our ability to exercise self-control is influenced by contextual cues. This study shows us how individual and situational factors can influence self-control.

Data - Both qualitative and quantitative data which were both extensive; very helpful to interpret the findings.

Research Method - Quasi lab experiment. Highly controlled environment to eliminate extraneous variables and able to determine cause and effect of IV on the DV, but lab study is low realism. Experiment 1 was in within their own homes, so there is more of a chance of distractions.

Ethical considerations - no major issues with the ethics of this study. Informed consent throughout, for both experiments and the scans are very low risk.

Ethnocentrism - Unlikely that the findings of this study are ethnocentric, however may be that impulse control is nurtured differently across societies so

cross-cultural differences could be noted.