Token Search, also known as Spatial Search, assesses your ability to retain and manipulate information in spatial working memory. To find all of the tokens, you are required to maintain and update an ongoing representation of previous searches, and to develop an appropriate searching strategy.
Some boxes will appear on the screen. A nice shiny token is hidden in one of the boxes.
Your task is to search through the boxes, by clicking on them, until you find a token. Once you have found a token, you have to remember where it was hidden, as a token will never be hidden in the same box again. Continue to search and collect tokens, until one has been found in every box.
When you are searching, you will lose a life and be given a new puzzle if you look in the same box twice before you find a token, or if you click on a box where a token has previously been found. You only have three lives, so use them wisely.
Once you have found one token in every box, a new puzzle will appear with more boxes, and more tokens.
In this test:
Accuracy does matter; if you click on a box that has already been searched before finding a token, or click a box that previously held a token, you will lose a life, and a simpler puzzle will appear. You have three lives. Errors do not subtract from your score, however, which is the maximum level you can reach.
Speed does not matter. You have as long as you'd like to search—but be careful, your memory may fade over time!
So to get maximum points, find searching strategies that minimize errors, and reach the highest level you can.
Knowing is half the battle. This is one of the more complex tasks, so it helps to know the rules before starting. Remember, there are two types of errors: clicking where a token was already found, and clicking the same box twice before finding another token.
Don't be afraid to experiment and make a few errors. The rules are hard to wrap your head around at first, but your performance will improve if you play around to get the hang of it and find a strategy that works for you.
You may find yourself retracing a systematic route and editing the locations along this route when tokens are found; if so, you have found one of the most successful problem solving approaches to this task!
Your score on this test contributes to:
Your short-term memory score (a lot).
Your reasoning score (a bit).
The contribution of each test to each performance category is based on a "factor analysis" that looked at how tests tend to clump together when measuring a massive set of data. The results were published in Neuron in 2012 (Hampshire, Highfield, Parkin, & Owen, 2012). The exact contribution of each test to each performance category may change as more data is collected.
The Science Behind Token Search
We have used versions of this task to investigate memory for nearly 20 years (Owen et al., 1990). The task is a version of the "traveling salesman problem," so called because it refers to the difficulty that traveling salesmen have in remembering which houses they have already visited and in which of those houses they have made a successful sale.
We have been investigating which areas of the brain are responsible for this type of memory by examining patients with damage to specific areas of their brains. We found that patients with frontal-lobe damage were impaired at the spatial search task even at very easy levels, despite performing well on equivalent verbal and visual working memory tests (Owen et al., 1996). By analyzing the sorts of errors that the patients made, we were able to show that this impairment was the result of them being unable to adopt an efficient searching strategy. Thus, their memory per se was not impaired, but their ability to organise the contents of memory was, suggesting that the frontal lobes are involved in monitoring and modifying behaviours (Owen, Evans, & Petrides, 1996).
Patients with temporal lobe damage or amygdalo-hippocampectomy lesions, on the other hand, were impaired only at the most difficult levels of this task. In addition, they performed poorly on a visual working memory version of this test. From this, we learned that these brain structures are responsible for memory capacity. Using positron emission tomography (PET) we also looked for areas of the brain that become activated in healthy volunteers when they perform the spatial search task (Owen et al., 1996). The results showed that posterior parietal cortex, the mid-dorsolateral and mid-ventrolateral frontal cortices and premotor cortices are all engaged when solving this task. However, close comparisons with other memory tasks showed that it was the mid-dorsolateral frontal region that really contributed most specifically to this task (Owen et al., 1996).
Token Search in the Real World
Although only legally available on prescription, so-called "cognitive enhancers" (otherwise known as smart drugs) are becoming increasingly popular alternatives to "everyday drugs" such as caffeine for boosting mental performance. Token Search may be one of the tests affected by such drugs.
One smart drug is methylphenidate (Ritalin), originally developed as an effective treatment for attentional deficit hyperactivity disorder (ADHD). Methylphenidate is now known to have cognitive enhancing properties, which include focusing of attention, increased alertness and better working memory. Together with our colleagues in the Department of Experimental Psychology in Cambridge, we have been looking into how this drug produces its beneficial effects on the brain and on behaviour. Performance on the Token Search task was found to improve while under the influence of methylphenidate (Mehta et al., 2000).
Brain scanning with PET revealed that this improvement was related to reductions in blood flow in the frontal and parietal cortices, structures previously associated with performance in this task. Please note that the use of cognitive enhancers has provoked strong ethical, social, and legal debate, and their use among non-clinical populations remains illegal in many countries.
Non-prescription "nootropics" include herbs and vitamins designed to boost cognition without the stigma of drugs. The results of tests like Token Search may be used to test their efficacy, though caution must be used until scientific results with healthy human participants has been conducted and published. In the meantime, a more established way to improve performance is to optimize sleep, exercise, and stress. For example, in one study (Williamson & Feyer, 2000), performance on a similar task plummeted by almost a whole level, on average, throughout the course of a day without sleep.
Log your own sleep, exercise, and stress to find out how they affect your own Token Search performance.
Mehta, M. A., Owen, A. M., Sahakian, B. J., Mavaddat, N., Pickard, J. D., Robbins, T. W (2000). Methylphenidate enhances working memory by modulating discrete frontal and parietal lobe regions in the human brain. Journal of Neuroscience. 20(6), RC65. Download PDF
Owen, A. M., Herrod, N. J., Menon, D. K., Clark, J. C., Downey, S. P. M. J., Carpenter, T. A., Minhas, P. S., Turkheimer, F. E., Williams, E. J., Robbins, T. W., Sahakian, B .J., Petrides, M., & Pickard, J. D. (1999). Redefining the functional organisation of working memory processes within human lateral prefrontal cortex. European Journal of Neuroscience, 11(2), 567-574. Read Abstract
Owen, A. M., Morris, R. G, Sahakian, B. J., Polkey, C. E. & Robbins, T. W. (1996). Double dissociations of memory and executive functions in working memory tasks following frontal lobe excisions, temporal lobe excisions or amygdalo-hippocampectomy in man. Brain, 119 (5), 1597-1615. Download PDF
Owen, A. M., Evans, A. C., & Petrides, M. (1996). Evidence for a two-stage model of spatial working memory processing within the lateral frontal cortex: a positron emission tomography study. Cerebral Cortex, 6(1), 31-38. Download PDF
Williamson, A. M., & Feyer, A. (2000). Moderate sleep deprivation produces impairments in cognitive and motor performance equivalent to legally prescribed levels of alcohol intoxication. Occupational and Environmental Medicine, 57, 649-655. Read Article