About Gidi Nave

PhD Candidate at Caltech, Computation & Neural Systems.

My research is in the field of Neuroeconomics – the intersection between Neuroscience, Psychology and Economics. I use a medley of theoretical and experimental methods for reverse-engineering the processes underlying human decision-making. By understanding how emotions and cognition generate judgments and decisions under uncertainty, I seek to contribute models that take into account the biological origins of the decision process in the brain.


Habits: our cognitive shortcut

I like my shopping routine at the grocery store around the corner, where my cart seems to easily navigate itself through the isles. Once in a while I make adventurous purchases (the Halloween-edition beer with pumpkin aroma still awaits in my fridge), but I usually stick to the products that have already made me happy before. Whenever in a new town, I try to shop at the same chain, where I know the products and their location on the shelves.

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Brain overload and self control

Many thoughts are running through my head as I aggressively strike the ‘holy trinity’ of strokes, ‘Control-alt-delete’. This is the nightmare of every ‘heavy’ software user: hours of work are about to go down the drain. I wish I hadn’t watched the YouTube that wasted precious computation power. I wish I had a faster processor, or at least a few more Gigabytes of working memory.

As engineers, we are constantly concerned with increasing the efficiency in which our products use limited resources. But as we try to save power and time by reducing computational and memory complexity, most of us are unaware of the limited resources of our brain – the CPU that lies within our skulls.

Last week I went road tripping with a friend to San Francisco. Driving on the highway, I could easily engage in conversation, listen to music and eat – all at the same time. Going off the highway made things more complex. I found it impossible to keep the conversation while trying to find my way through the allies of Mission district. The brain has a limited budget of mental effort, and by multi-tasking I risked getting to the ‘control-alt-delete’ state of my mind.

When we buy a new computer, its hardware capabilities are stated on the box or in the manual. Using sophisticated experiments, cognitive psychologists are trying to reverse-engineer the hardware limitations of our brains, and understand what might be the consequences of over-loading it. In terms of working memory, the magical number of objects that the average human being can store is thought to be seven, plus or minus two.  Psychologists ‘load’ the brains of subjects by incentivizing them (with real money) to memorize a varying number of digits; the consequences of this mental burden on our working memory are quite surprising. In a famous 1999 experiment, a group of Stanford researchers asked college undergrads to memorize a few digits, and then walk over to the room across the hall to recall them. On the way, they encountered a food cart, where they could choose between a chocolate cake and a healthier alternative – a fruit salad. Subjects that were asked to memorize seven digits were ~50% more likely to choose the unhealthy (but tasty) cake than subjects who were asked to memorize only two digits. Similar experiments in other domains, demonstrated that when the human CPU is loaded, people tend to ‘lose control’ by making selfish choices, spending money on impulsive purchases and using sexist language.

Cognitive load ahead

CPU power requires energy, and so is the case for our mind, whose preferred fuel is the sugar glucose. Just like after physical efforts (such as moving an apartment), following extensive mental exertions (for example a long exam) we find ourselves desperately looking for sugar in order to refill our mental batteries. This is a dangerous combination for dieters, whose self-control capabilities are anyways degraded because of the mental effort. Psychologists know the process of losing self-control as a result of decreasing brain-CPU power as ‘ego depletion’.

A group of Israeli researchers examined how ego depletion might affect fatal judgments requiring extreme mental effort – decisions of prison parole boards. Turns out that the odds that a prisoner will be successfully paroled dramatically drops from almost 65% at the start of the day (after breakfast) to almost none when the board members’ sugar level plummets, before lunch. Upon returning from their break, with their mental batteries loaded, the odds that the judges will turn around their default ‘NO’ abruptly rise to 65%, and then decline again. Prisoner’s fate is dramatically influenced by the random time for which his hearing was scheduled.

How can we avoid the loss of self-control and our degrading judgment capabilities? Obviously, extending our working memory or adding another CPU core is not an option for our minds. Perhaps making sure that we eat well, sleep enough and take a short break to keep our stress levels low is a start. Understanding the limitation of our brains might help us in forgiving our friends and ourselves, for the occasional bad decisions we all make sometimes.