Is the glass half full or half empty: optimism and rACC activation


The title of this post seems to be an age old question that is suppose to test your general optimism. The optimist among us views the glass as half full, while the pessimist see it as half empty. Do you think you will be successful or do you think things will be difficult for you? Do you think the current bad economy is going to turn around quickly or are we going to have a serious recession/depression?

(This post can be taken in fuller context by also reading yesterdays post on the difference in imagining yourself currently or in the future.)

Interestingly, overall humans are an upbeat optimistic organism and this attitude probably makes it easier for us to get through tough times (sounds like hope – see this blog piece on the neuroscience of hope). But there can also be over optimism. Overly optimistic thoughts of the future might play an important role in the various economic bubbles we have experienced in the past (Dutch tulip fever), and more  recent times (2001 bubble, 2007/8 housing/stock bubble).

However, there are many benefits to having an optimist attitude (e.g. you think you will own a house in the future) that includes living a longer life, less likely to have a heart attack or drinking problem (according to this short preview to the paper I discuss below – Schacter and Addis, Nature Neuroscience, 2007.

Research Paper:

Sharot et. al., Nature, 2007 wanted to examine what regions in the brain may underlie individual differences in optimism levels.

The subjects were asked to imagine past or simulate future events such as a break up of a relationship or winning an award while having their brains scanned (MRI). The subjects also scored the imagined event (past or future) as negative, neutral, or positive. After the scans were done the subjects where then asked to give further ratings such as how vivid and strong the imagined event were.

Later all subjects also undertook a test to determine their level of optimism, which included similar questions to the ones I asked at the beginning of this post.


In general subjects felt that positive future events were closer in time than negative events (which again suggest an optimistic bias). Additionally, the subjects judged future positive events more positive than past positive events (this somewhat surprised me – since the past is real where the future is just a hope. But the past has already been experienced so does not have that novelty/hopeful factor). Both of the above two observations were greater in the more optimistic subjects, as you would expect.

Optimistic individuals had greater activation of the rostral anterior cingulate cortex (rACC) (the exact same brain area discussed in my post from yesterday) when imaging positive future events compared to negative future events than non-optimistic subjects. Additionally, overall when subjects imagined future positive events there was a great correlation between rACC and amygdala (important for emotional processing) activation than when subjects imagined future negative events. This would account for the general higher vividness and strength of future positive events compared to negative future events since the amygdala activation would add greater ‘emotional’ value to the imagination/experience.

Among all the conditions the future negative event produced the least amount of amygdala and rACC activation compared to the other three (past positive events, past negative, future positive). This would suggest we tend not to ‘see/feel’ the potential negative future possibilities (less emotions evoked) and hence are overall optimistic about the future because we can’t see/feel the negative (or we choose not to see the negative).

But returning to the optimistic individuals – they had greater activation of the rACC (and greater correlation between rACC and the amygdala) than the less optimistic individuals. These results make sense when we think of other wider perspective research.

Depressed subjects display reduced metabolism and volume of the rACC region. And as you can imagine depressed subjects have less optimism than the non-depressed individuals (in fact among the deeply depressed many can not, or do not want to, think of the future – because things are so bleak to them. I am sure you could even suggest that part of deep depression/suicide is total loss of hope).

Comparison between future thinking and optimism:

Now do these results of the role of rACC activation in optimism make us rethink the results I presented yesterday (longevity and future thinking) which suggested that rACC activation (when thinking of you now vs future) plays a role in future discounting (the subjects with the largest future discounting had higher activation of rACC in the now vs future comparison (meaning less activation of rACC in the future imagination of themselves – which the authors concluded meant these subjets thought of their future self as a stranger).

Is it possible that the subjects who had less rACC activation when thinking of themselves in the future were just less optimistic about their future? And it would make sense if you are less optimistic about your future self then you would place less value on future events – and hence you would discount the future at a greater rate since you don’t think it will turn out well. Therefore, it would make sense that you would take the 10 dollars now than the 15 dollars in a month.

However, as pointed out in this preview article of Sharot’s paper too much optimism is also not a good thing. If you are overly optimistic about the future then maybe you would not take appropriate safety measures (such as in our ancient ancestor’s time having a cache of food, or in our current world money saved up). One could argue a large contributor to our current financial crisis is the vast majority of individuals in the developed world were too optimistic about the future (they drank – overdosed on – the koolaid). They wore the rose tinted (or should I say the green tinted) glasses that colored their view of the world, of the future and they did not see the reality of the situation. Hence, took on overly optimistic debt load (personal level) or overly leveraged their position (banking/financial sector).

I would guess like most other things in biology we are talking about an inverted U curve – and too little or too much optimism is a problem. The trick is to have the appropriate level of optimism for the current environmental conditions (and be willing to change if the environment changes on you).

Can society at large have an overall change in optimism levels that might play a role in stagnation at one extreme or economic bubbles at the other? What could be possible biological explanations behind this?

Can we separate the role of rACC in both optimism and future discounting (with optimistic individuals have less discounting (at least in most cases until maybe they become too optimistic) – are we talking the same thing in both cases or could under appropriate experimental setting differentiate between optimism and reduced hyperbolic future discounting?

Good science, or at least interesting science results in more intriguing questions.