assumes that behaviour can be largely explained in terms of biology

Aimed to find out if ppts who were 'low delayers' on the marshmallow test at age 4, had also reported low self-control on psychometric measures in their 20s and 30s:

1. Would show more errors on go/no go task if stimuli was 'hot' (rewarding emotional faces) than those ppts who had shown consistently high self-control (the 'high-delayers)

quasi experiment- but in a lab

IV: high/low delayers

DV: performance/ reaction times/ accuracy/ FMRI scans

repeated measures design

longitudinal

age 4: 562

age 30: 135

age 20: 155

volunteer sampling

1. 59 ppts tested on self-control, required them to perform an action given a certain stimuli (go - press button) and not perform the action when presented a different stimuli (no-go - don't press button). Errors or false alarms would be to press the button (go) when the no-go stimuli was presented. 'hot' stimuli was happy faces. 'cool' stimuli was neutral or fearful faces. All 59 ppts completed 4 versions of the go/no go task. Faces were shown on a laptop in their home. Each face appeared for 500m/s with a 1s interval between each time.

2. 26 ppts- 25 high delayers, 11 low delayers. 2s-14s delay intervals were used where ppts rested looking at a fixation point in between. there were 48 trials per run, 35 go trials and 13 no-go trials. stimuli and instructions were the same as exp 1 but this time the stimuli was presented on a screen in the scanner and a different type of button was used.

1. accuracy. more errors on the 'no-go' tasks: happy- low- 15.7% high- 11.2%. fearful- low- 12% high- 10.4%

1. low delayers who showed difficulty in delaying gratification at 4 years old, showed more difficulty in stopping responses to happy faces in their 40s. suggests low self control remains consistant in an individual

2. show lower activity in their right prefrontal cortex, suggesting lower response inhibition to stimuli

3. would show increased activity in the ventral stratum, where positive or rewarding cues are processed, than the higher delayers

2. accuracy. low delayers; 14.5% high delayers; 10.9% low delayers showed lower activity in the right inferiour frontal gyrus than the high delayers on the no go traits (suggesting this region plays an important role in the withholding of responses).

2. delay ability is hindered by rewarding cues. hot and cool processing systems in the brain affect self control.