Skip to main content

Danilo Díaz Granados read: Young Adults With Better Navigation Skills Do Not Have Larger Hippocampi, Raising Questions About The Meaning Of The Famous Taxi Driver Studies

GettyImages-165671507.jpgBy Christian Jarrett

The famous studies of London’s taxi drivers – showing they have larger hippocampi (the comma-shaped brain structure in the temporal lobes) than controls – have become a staple of undergrad psychology courses and a classic example of how your brain changes according to what you do with it. Many other studies have also implied an association between hippocampal size and navigational ability – for instance, people with Alzheimer’s, who have lost neurons in this brain structure, tend to experience problems finding their way around. For some time, then, an obvious, though tentative, inference has been that better navigators have bigger hippcampi, with London taxi drivers (and their mastery of “the knowledge” of the city’s convoluted streets) and people with Alzheimer’s representing opposite extremes of the spectrum. However, a new study, released as a preprint at bioRxiv, raises questions about how far we can safely generalise from the taxi driver and Alzheimer’s-based research.

Steven Weisberg and his colleagues tested young adults’ navigation skills and assessed the size of their hippocampi and found the two were not significantly correlated. “The hippocampus plays a crucial role in spatial navigation in humans, but the volume of the hippocampus may not be a biological marker for navigation ability among typical populations,” the researchers concluded.

The ninety participants (average age 23; 54 women) had their brains scanned and they completed a range of psychological questionnaires and tests, including a series of computer-based navigation tasks. These navigation tasks required them to learn the routes between buildings in a virtual environment, to point to the location of various buildings, and to drag and drop buildings in the correct location from memory as a way to test their ability to form a cognitive map of the environment.

Critically, the researchers did not find a significant correlation between hippocampi volume and navigation performance, which varied widely across the participants. This was true whether looking at overall hippcampal volume, right hippocampus only or right posterior hippocampus, and remained the case when controlling for differences between participants in other cognitive and demographic factors, such as their mental rotation ability, verbal IQ and gender.

Weisberg and his team believe there are at least three explanations for their null results. First, perhaps the association between hippocampus size and navigation ability only pertains to extreme groups, like taxi drivers and people with Alzheimer’s, and not to the spread of ability in the general population. Second, perhaps hippocampi volume is too crude a measure, with navigational ability depending more on connectivity within the hippocampus and between the hippocampus and other relevant brain areas. Last, maybe  hippocampi volume is associated not so much with navigational skill, but the use of particular navigational strategies (raising questions about what kind of cognitive processes exactly the London taxi drivers’ “knowledge” depends on – for instance, the researchers suggested, perhaps it relies not a cognitive map in the usual sense, but rather “an enormous catalogue of associational data”).

Although the new findings represent much needed research on the neural basis of navigational skills among the healthy general population, they are limited by the study’s use of computer-based navigation tasks – it’s possible the results would have been different using a task in the real world. Also, there was no assessment of brain activity and no measure of the kind of navigational strategies the participants used, so we can’t know what part they may have played in the results.

The researchers said future research could address these shortcomings but that as things stand their paper has “implications for the role of the hippocampus in general navigation, and for the extrapolation of findings in expert and impaired groups to healthy, young adults.”

—Everyday taxi drivers: Do better navigators have larger hippocampi? [this study is a preprint meaning that it has not yet been peer reviewed and the final published version may differ from the version that this report was based on]

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest



View Source

Popular posts from this blog

Danilo Díaz Granados read: “Skunk” Cannabis Disrupts Brain Networks – But Effects Are Blocked In Other Strains

By Matthew Warren Over the past decade, neuroimaging studies have provided new insights into how psychoactive drugs alter the brain’s activity. Psilocybin – the active ingredient in magic mushrooms – has been found to reduce activity in brain regions involved in depression , for example, while MDMA seems to augment brain activity for positive memories . Now a new study sheds some light into what’s going in the brain when people smoke cannabis – and it turns out that the effects can be quite different depending on the specific strain of the drug. The research, published recently in the Journal of Psychopharmacology , suggests that cannabis disrupts particular brain networks  – but some strains can buffer against this disruption. Cannabis contains two major active ingredients: tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is responsible for many of the drug’s psychoactive effects, such as the feeling of being stoned and the anxiety that people sometimes feel, as well as ...
Read more

Danilo Díaz Granados read: Beyond the invisible gorilla – inattention can also render us numb and anosmic (without smell)

By Emma Young It’s well-known that we can miss apparently obvious objects in our visual field if other events are hogging our limited attention. The same has been shown for sounds: in a nod to Daniel Simons’ and Christopher Chabris’ famous gorilla/basketball study that demonstrated “inattentional blindness”, distracted participants in the first “inattentional deafness” study failed to hear a man walking through an auditory scene for 19 seconds saying repeatedly “I am a gorilla”. Now, two new studies separately show that a very similar effect occurs in relation to touch ( inattentional numbness ) and to smell   ( inattentional anosmia ).   Sandra Murphy and Polly Dalton (a co-author on the inattentional deafness paper) at Royal Holloway, University of London report in the journal Cognition on inattentional numbness. They wanted to go beyond the way we rapidly tune out ongoing tactile stimulation, like the sensation of our clothes, and explore what happens when we’re tou...
Read more

Danilo Díaz Granados read: A New Study Has Investigated Who Watched The ISIS Beheading Videos, Why, And What Effect It Had On Them

By Emma Young In the summer of 2014, two videos were released that shocked the world. They showed the beheadings, by ISIS, of two American journalists – first, James Foley and then Steven Sotloff. Though the videos were widely discussed on TV, print and online news, most outlets did not show the full footage. However, it was not difficult to find links to the videos online. At the time, Sarah Redmond at the University of California, Irvine and her colleagues were already a year into a longitudinal study to assess psychological responses to the Boston Marathon Bombing, which happened in April 2013. They realised that they could use the same nationally representative sample of US adults to investigate what kind of person chooses to watch an ISIS beheading – and why. Their findings now appear in a paper published in American Psychologist .   By late spring 2013, the researchers had recruited 4,675 adults online, and assessed their mental health, TV-watching habits, demographics,...
Read more