I made a summary of all the analysis done by the authors of the paper.
Generally speaking, this paper has overall three(or two) angles:
1) The separate and joint sensitivities to gains and losses
2) Coding mechanism of gains and losses (measured by the comparison of activities between the worst gambles and the best gambles)(This angle could also be seen as an extension of the first one)
3) The relationship between neural and behavioral loss aversion
There were too many analysis in the paper. This summary might not be so brief though I tried to make it as easy to understand as possible. It would be nice if they could provide us with some insights about the continuing work about our group project.
The three (or two) angles above were realized through around seven analysis. They come as follows:
1.
Purpose:
1)To examine the neural systems that process decision utility
2)To assess behavioral sensitivity to gains and losses
Experiment details:
1)Participants decided whether to accept or reject mixed gambles that offered a 50/50 chance of either gaining one amount of money or losing another amount of money.
2)Gain:$10-$40; loss:$5-$20
Statistical analysis:
Logistic regression
Results:
Behavioral loss aversion \lambda— — the ratio of the loss response to gain response
Conclusions(consistent with previous findings):
1)Participants were indifferent to gambles in which the potential gain was twice the amount of the potential loss.
2)Participants were slower to decide whether or not to accept these gambles.
2.
Purpose:
To identify brain regions whose activation correlated with the size of the potential gain/loss.
Statistical analysis:
1)Using parametric regressors with the imaging data.
2)A conjunction analysis between increasing activity for gains and decreasing activity for losses.
Results:
The gain-responsive and loss-responsive network regions.
Conclusions:
For the first analysis:
1)No decreasing activation as gains increased.
2)no significant increasing activation but some decreasing activation in some brain regions as loss increased.
For the second analysis:
1)There existed joint sensitivity to both gains and losses in a set of regions.
2)There existed a pattern of neural loss aversion(more details in the sixth angle).
3.
Purpose:
To ensure potential loss-related responses were not being obscured by the overall positive expected value of the gambles
Statistical analysis:
Comparing activity evoked by the worst possible gambles(gain:$10-$16; loss:$17-$20) and the best possible gambles(gain:$34-$40; loss:$5-$8)
Conclusions:
There was no increasing activity for the worst gambles compared to the best gambles.
4.Further analysis to two specific areas that have loss-related activity
Results:
1)No significant loss-related activity in the two areas.
2)Large activation for the best gambles to the worst gambles in another region.
Conclusions(consistent with previous findings):
1)Losses and gains are coded by the same mechanism rather than by two separate mechanisms.
2)There existed increased and decreased activity in the striatum for experienced monetary gains and losses, respectively.
5.Investigation: whether individual differences in brain activity during decision-making were related to individual differences in behavior
Purpose:
To identify regions where the neural response to gains or losses was correlated behavioral loss aversion
Results:
For behavioral loss aversion:
1)As gains increased, there did exist a significant correlation between behavioral loss aversion and gains.But there were only two cortex showing that.
2)As losses increased, there existed a significant correlation between behavioral loss aversion and losses. Moreover, there were many areas showing a more rapidly decreasing response to losses among individuals who were more loss averse.
For neural loss aversion:
Many of the regions that had significant correlation between behavioral loss aversion and losses showed decreasing neural activity as losses increased.
Conclusion(consistent with previous findings):
Some forms of risk taking may have their roots in sensation seeking by individuals who have a diminished physiological response to stimulation.
6.Examination of specific regions from the gain/loss conjunction analysis
Results:
The slope of the decrease in activity for increasing losses was greater than the slope of the increase activity for increasing gains.
Conclusions:
There existed a pattern of neural loss aversion.
7.
Purpose:
To assess the relationship between neural loss aversion and behavioral loss aversion.
Statistical analysis:
a whole-brain robust regression analysis
Results:
There were significant correlations between behavioral and neural loss aversion.
Conclusions:
Differences in behavior were strongly predicted by differences in neural responses.
I made a summary of all the analysis done by the authors of the paper. Generally speaking, this paper has overall three(or two) angles: 1) The separate and joint sensitivities to gains and losses 2) Coding mechanism of gains and losses (measured by the comparison of activities between the worst gambles and the best gambles)(This angle could also be seen as an extension of the first one) 3) The relationship between neural and behavioral loss aversion There were too many analysis in the paper. This summary might not be so brief though I tried to make it as easy to understand as possible. It would be nice if they could provide us with some insights about the continuing work about our group project. The three (or two) angles above were realized through around seven analysis. They come as follows:
1. Purpose: 1)To examine the neural systems that process decision utility 2)To assess behavioral sensitivity to gains and losses
Experiment details: 1)Participants decided whether to accept or reject mixed gambles that offered a 50/50 chance of either gaining one amount of money or losing another amount of money. 2)Gain:$10-$40; loss:$5-$20
Statistical analysis: Logistic regression
Results: Behavioral loss aversion \lambda— — the ratio of the loss response to gain response
Conclusions(consistent with previous findings): 1)Participants were indifferent to gambles in which the potential gain was twice the amount of the potential loss. 2)Participants were slower to decide whether or not to accept these gambles.
2. Purpose: To identify brain regions whose activation correlated with the size of the potential gain/loss.
Statistical analysis: 1)Using parametric regressors with the imaging data. 2)A conjunction analysis between increasing activity for gains and decreasing activity for losses.
Results: The gain-responsive and loss-responsive network regions.
Conclusions: For the first analysis: 1)No decreasing activation as gains increased. 2)no significant increasing activation but some decreasing activation in some brain regions as loss increased. For the second analysis: 1)There existed joint sensitivity to both gains and losses in a set of regions. 2)There existed a pattern of neural loss aversion(more details in the sixth angle).
3. Purpose: To ensure potential loss-related responses were not being obscured by the overall positive expected value of the gambles
Statistical analysis: Comparing activity evoked by the worst possible gambles(gain:$10-$16; loss:$17-$20) and the best possible gambles(gain:$34-$40; loss:$5-$8)
Conclusions: There was no increasing activity for the worst gambles compared to the best gambles.
4.Further analysis to two specific areas that have loss-related activity
Results: 1)No significant loss-related activity in the two areas. 2)Large activation for the best gambles to the worst gambles in another region.
Conclusions(consistent with previous findings): 1)Losses and gains are coded by the same mechanism rather than by two separate mechanisms. 2)There existed increased and decreased activity in the striatum for experienced monetary gains and losses, respectively.
5.Investigation: whether individual differences in brain activity during decision-making were related to individual differences in behavior
Purpose: To identify regions where the neural response to gains or losses was correlated behavioral loss aversion
Results: For behavioral loss aversion: 1)As gains increased, there did exist a significant correlation between behavioral loss aversion and gains.But there were only two cortex showing that. 2)As losses increased, there existed a significant correlation between behavioral loss aversion and losses. Moreover, there were many areas showing a more rapidly decreasing response to losses among individuals who were more loss averse. For neural loss aversion: Many of the regions that had significant correlation between behavioral loss aversion and losses showed decreasing neural activity as losses increased.
Conclusion(consistent with previous findings): Some forms of risk taking may have their roots in sensation seeking by individuals who have a diminished physiological response to stimulation.
6.Examination of specific regions from the gain/loss conjunction analysis
Results: The slope of the decrease in activity for increasing losses was greater than the slope of the increase activity for increasing gains.
Conclusions: There existed a pattern of neural loss aversion.
7. Purpose: To assess the relationship between neural loss aversion and behavioral loss aversion.
Statistical analysis: a whole-brain robust regression analysis
Results: There were significant correlations between behavioral and neural loss aversion.
Conclusions: Differences in behavior were strongly predicted by differences in neural responses.