biological : casey

aim

• does delay of gratification in children predict impulse control abilities and sensitivity to alluring or social cues at the behavioural and neural level when ppts are in their 40s

method

• quasi experiment

• longitudinal study

sample

• 4yo’s - 562 ppts did delayed gratification task

• 20yo’s - 155 did self control scales

• 30yo’s - 135 self control scales

• 40yo’s - 117 divided into high delayers and low delayers based on above experiments

variables

• IV : if ppts were high delayers or low delayers

• DV’s :

• behaviour - the performance on the impulse control task (experiment 1)

• neural - measured by results of fMRI scans (experiment 2)

experiment 1 procedure

• self control was measured by a go / no-go task

• requires ppts to push a button when they see a certain stimulus and not push a button when they see a different one

• go = push button

• no-go = don’t push it

experiment 2 procedure

• fMRI was used to examine activity in the ventral striatum and inferior frontal gyrus to see if it correlated with delay of gratification

• ppts completed a hot version of go / no-go task

• electronic response pad was used to record responses to facial stimuli and reaction times

experiment 1 results

• reaction times - no effects of delay group on reaction time

• accuracy - both groups performed with a high level of accuracy, cool tasks 99.8% correct, hot tasks 99.5% correct

• on no-go trials low delayers committed more false alarms than high delayers (low 14.5%, high 10.9%)

• on cool task low and high delays performed similarly

• on hot task, low delayers performed worse

experiment 2 results

• reaction times - no sig difference

• accuracy - high for both groups across ‘go’ trials (98.2% correct hits) and no-go trials had 12.4% false alarm rate, on no-go trials low delayers committed more false alarms in hot task than high delayers

• fMRI - right inferior frontal gyrus was involved in withholding responses, low delayers show reduced activity in inferior frontal gyrus and high activity in ventral striatum compared to high delayers especially on hot no-go task

conclusions

• overall the go / no-go task produced differences between the delay groups only in the presence of emotional ‘hot’ clues

• individuals who had more difficulty delaying gratification at 4 (low delayers) showed more difficultly as adults in suppressing responses to happy faces than the high delayers

• ability to resist temptation is supported by neural networks in the brain

• resistance to temptation is a relatively stable characteristic of an individual over time

sampling bias

• volunteers from the original 562

• large sample dropout

• not representative as only a certain type of person would’ve repeatedly agreed (from 562 to 27 in final experiment)

validity

• high internal as high level of control

• low external as not looking at faces for 1/10th of a second during a conversation

ethics

• is ethical

• consent given by ppts

• fMRI may have been stressful

research method

• lab procedure

• high control but did it at home

• standardised procedures used

type of data

• quantitative data as measuring if they did / didn’t push button

• looking at brain scans - was either active or not

reliability

• high reliability as standardised procedures used

• high external as they repeated it

practical applications

• more evidence of localisation of the brain

• different areas of the brain responsible for different things

• could help improve impulse control

ethnocentrism

• is ethnocentric

• same university nursery

• American bias

• children most likely from same / similar socio-economic backgrounds