Month: August 2018

By Emma Young

It’s well-known that we can easily miss objects in our environment that are outside the focus of our conscious attention. “Inattentional blindness” is demonstrated by the famous “invisible gorilla” studies, for example. But there’s a darker side to this phenomenon: if it happens while you’re driving – or if you’re a baggage checker at airport security – the consequences could be fatal.

Now a new paper, by Joshua Eayrs and Nilli Lavie at University College London, published in the Journal of Experimental Psychology, shows that some people can handle more visual information than others before developing this and related kinds of attentional blindness, and this is because they have a greater visual perceptual capacity. “We identified a novel trait that is different from working memory, general intelligence or motivational factors,” Lavie said in a press release. 

In initial studies conducted on 279 visitors to the Science Museum in London, Eayrs and Lavie first assessed participants’ perceptual capacity by asking them to rapidly identify the total number of objects in a scene – a so-called “subitizing” task that measures “the simultaneous, parallel processing capacity for detection and individuation of items”. A series of 162 images of between one and nine randomly sized and positioned black squares were presented for 100 milliseconds each. Previous work has found that, on average, people can reliably enumerate about three to four items and a mean of 3.62 was found for this group. 

The researchers then found that people who were better at subitizing – suggesting that they have higher perceptual capacity – were also better at identifying whether two photographs, presented briefly in rapid succession, were identical or very nearly identical (that is, they were less susceptible to a form of inattention known as “change blindness”). 

In a second study, on 122 more visitors to the Science Museum, the researchers linked a greater subitizing capacity to being less susceptible to “load blindness” as revealed by their superior performance on a task that progressively increased the perceptual load (participants had to try to judge the lengths of lines of an X while also monitoring other changeable elements in the periphery of the scene). 

In a third study, the researchers explored whether the superior performance of participants with higher perceptual capacity was simply because they have greater working memory capacity.  Working memory describes how much information we can hold and manipulate in mind at any time and it’s a key aspect of cognitive functioning that is known to underlie performance on a range of mental tasks, including tests of attention.

A separate group of 43 people completed three different tasks of working memory, as well as the same subitizing task as before, the same change-detection task, and also an object-tracking task, which required them to track four target dots as they moved around the centre of a screen, among four other dots. 

While working memory capacity did partially explain object-tracking performance, subitizing performance was also important. Also, perceptual capacity (indicated by results on the subitizing task) strongly predicted the participants’ performance on the photograph change-detection task, even when working memory capacity was controlled for.

“Taken together, the results indicate that a single unifying construct appears to underlie subitizing, change detection and [object-tracking] and this construct is distinct from working memory capacity,” the researchers write. 

Importantly, they say, the work also establishes the subitizing task as a simple way of quantifying an individual’s general perceptual capacity limit. As such, it provides “a potentially powerful indicator of individual abilities relevant to various tasks” – such as working as a pilot or a baggage screener at an airport. “The present research thus provides a scientific basis for devising future personnel selection tests for security and defense,” Eayrs and Lavie conclude.

—Establishing Individual Differences in Perceptual Capacity

Image via Giphy.com

Emma Young (@EmmaELYoung) is Staff Writer at BPS Research Digest

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By Alex Fradera

The “Big Society” initiative – launched at the turn of this decade by the incoming British government – was a call for politics to recognise the importance of community and social solidarity. It has since fizzled out, and for a while communitarianism fell out of the political conversation, but it has returned post-Brexit, sometimes with a nationalist or even nativist flavour. The US political scientist Robert Putnam’s research is sometimes recruited into these arguments, as his data suggests that racially and ethnically diverse neighbourhoods have lower levels of trust and social capital, which would seem an obstacle to community-building. But an international team led by Jared Nai at Singapore Management University has published a paper in the Journal of Personality and Social Psychology that suggests that diverse neighbourhoods are in fact more likely to generate prosocial helpful behaviours.

Putnam’s work tallies with a distinguished psychological idea, conflict theory, which suggests salient distinctions between people in an area heightens a sense of competition between groups over resources. Because race is so visible – neuroscientific studies suggest we perceive it earlier even than gender – the argument goes that racially diverse areas lead people to, as Putnam puts it, hunker down and withdraw. Consistent with this view, Putnam’s data shows that multicultural areas have lower levels of trust – even between people of the same race – and some evidence, but not all, has shown this has a knock-on adverse effect on civic engagement and volunteering.

Nai’s team predicted that despite this, racially diverse areas would show more, not less prosocial helping. They drew on contact theory, which suggests that active contact with people from other groups humanises them. In particular, such contact leads people to view their own identity as broader, potentially encompassing all of humanity – this could be a mechanism to encourage prosociality. As most of the contact theory work puts people in extended face to face interactions, the question was whether mere ambient diversity will help (simply being around other people who look different).

A first study showed that diverse areas have a more prosocial online buzz. Nai’s team pulled 60 million tweets and identified the usage frequency of words from James Pennebaker’s “prosocial dictionary” that are known to correlate with a desire to help others. Indexing across 200 metropolitan areas, they found that tweets from more racially diverse areas used prosocial language more frequently. But language is an indirect measure, and it may be that people with that style voluntarily move into areas that are more diverse. So Nai’s group looked at international data, as moving country is rarer than moving cities, and at levels of actual (reported) helping. The data came from a 2012 Gallop World Poll that asked “in the past month, have you helped a stranger?”. Across 128 countries, Nai’s team found that it was the more ethnically diverse countries that scored a greater frequency of yes responses to this question.

Next, Nai’s team wanted to see if the factor that turned diversity into helping was people having a broader sense of identity. They surveyed US people online using the same helping question used in the Gallop poll, and replicated the greater diversity/greater helping correlation for different zip codes for around 500 participants (good gender balance, average age 33). They also asked the participants how much they identified with three groups: people in my community, Americans, and all humans everywhere. They found that diverse neighbourhoods were associated with higher identification with all of humanity, and statistical analysis suggested, but could not prove, that this (and only this) form of identification was driving the helping behaviour.

Finally, the researchers looked at help for outsiders during a crisis. Real data from a helping website set up following the Boston marathon showed that more offers of help came from zip codes that were more racially diverse, even after controlling for distance from site and wealth of the zip code. And in an online experiment, 300 participants stated they would be more likely to offer help following a bombing when they had been asked to imagine living in a very diverse neighbourhood – again mediated by a greater sense of connection to humanity. 

All the studies controlled for a range of factors related to area or nation, such as income / national economics, education, urbanisation, and religious diversity. One weakness is that apart from the last study, all this work is correlational. It would be interesting to track neighbourhoods over time to see how changes have an impact dynamically – maybe an area renowned for its diversity that evolved organically over decades would have a different attitude to the idea of “one humanity” than a neighbourhood with no sense of itself as diverse per se and that had changed fairly rapidly due to impersonal market or governmental forces. 

An interesting detail from the international study is that trust scores (available for a subset of nations) were lower in more ethnically diverse countries, in line with the Putnam data. So it seems that a populace can both be less trusting and more willing to help strangers, which is something to puzzle on. But regardless, the new data pushes back against the assertion that diverse neighbourhoods struggle to show communal spirit, and suggests that ambient contact with those superficially different can underscore our common humanity and obligations to one another.

—People in more racially diverse neighborhoods are more prosocial

Alex Fradera (@alexfradera) is Staff Writer at BPS Research Digest 

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By Emma Young

Scent plays an often under-appreciated role in sexual attraction, helping to account for why visual attractiveness alone can’t explain just how physically attractive a person is perceived to be. But what role does our ability to smell our partners – or potential partners – play in actual experience? 

We know from past research that men born without the ability to smell tend to have fewer sexual partners. And about half of people who lose their sense of smell, through infection or injury, report negative impacts on their sexual behaviour. However, this could be an indirect effect – an inability to smell is often also associated with depression or social insecurity, which can affect aspects of sexuality – and such studies do not tell us whether sense of smell is related to sexual experience among healthy people. Now, in a new paper in Archives of Sexual Behavior, Johanna Bendas at the Technical University of Dresden, Germany, and her fellow researchers report evidence from healthy, young adults showing precisely that.

The researchers studied 42 women and 28 men aged between 18 and 36. They found that there was no relationship between their odour sensitivity (measured using a test that establishes how much of a smelly chemical must be present for the individual to be able to detect it) and either sexual desire or sexual performance (defined as how many times they’d engaged in sexual activity during the previous month and how long, on average, a sexual encounter had lasted).

However, people with a keener sense of smell reported finding their sexual activities more “pleasant”, and women with a greater sensitivity to odours had more orgasms during sex. 

“Our data suggest a positive influence of olfactory sensitivity on the sex life of young and healthy participants,” the researchers write. “The perception of body odors such as vaginal fluids, sperm and sweat seems to enrich the sexual experience” by increasing sexual arousal, they add.

There are some limitations to the study, including the correlational design which means other unknown factors might be playing a causal role. Also, while the researchers did control for the use of hormonal contraception in the women, they didn’t consider the stage of menstrual cycle of the female volunteers at the time of the study – something that is known to influence olfaction. Future research in this area should take this into account, and could further explore the influence of specific odours. “The direct measurement of sexual arousal or experience will give further insight into the assumption that olfactory sensitivity improves sexual experience,” the researchers write.

—Olfactory Function Relates to Sexual Experience in Adults 

Emma Young (@EmmaELYoung) is Staff Writer at BPS Research Digest

 

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