The head of a brown lion. Multiple tiny, green, spinning Catherine wheels with red edges. Colourful fragments of artillery soldiers and figures in uniform and action. Unfamiliar faces of well-groomed men… These are just a few of the hallucinations reported by a group of people with macular degeneration (MD), a common cause of vision loss in people aged over 40.
About 40 per cent of people with MD – who lose vision in the centre of their visual field but whose peripheral vision is generally unaffected – develop Charles Bonnet syndrome (CBS), reporting hallucinations that vary from simple flashes of light and shapes to faces, animals and even complex scenes.
It has been suggested that CBS might arise as a result of over-responsiveness – “hyper-excitability” – of certain visual regions of the cortex, after they are deprived of normal retinal input. But whether this really is the case –and why some people with reduced vision or blindness develop them, while others don’t – has not been clear. Now new work by a team of psychologists at the University of Queensland, Australia, led by David Painter, and published in Current Biology, offers some answers.
This is Episode 14 of PsychCrunch, the podcast from the British Psychological Society’s Research Digest, sponsored by Routledge Psychology. Download here.
Can psychology help your cooking taste better? Our presenter Ginny Smith hears about the importance of food presentation, pairing and sequencing, and how our perception of food is a multi-sensory experience. She and her friends conduct a taste test using “sonic seasonings” that you can also try at home.
The idea that the language that you speak influences how you think about and experience the world (the so-called Sapir-Whorf hypothesis) has a long and storied history. A lot of research into the issue has focused on colour perception, and evidence has accumulated that people whose native languages have different colour categories don’t see the world in quite the same way.
Now in a new paper, published in Psychological Science, Martin Maier and Rasha Abdel Rahman at the Humboldt University of Berlin report that by affecting visual processing at an early stage, such linguistic differences can even determine whether someone will see a coloured shape – or they won’t. “Our native language is thus one of the forces that determine what we consciously perceive,” they write.
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).
Now a team led by Sarah Ketay at the University Hartford have shown how this absorption of friends into our self-concept can manifest at a visual level, affecting our ability to distinguish their faces from our own. Writing in the Journal of Social and Personal Relationships, Ketay’s team said “The present research supports the idea that close others are processed preferentially and may overlap with the self.”
The fallibility of eye-witness memory has been well-documented by psychologists, including how alcohol intoxication undermines witness accuracy still further. In fact, psychological research into the foibles of human memory and the implications this has for legal proceedings is arguably one of the best examples of the discipline making a practical contribution to everyday life.
And yet, as Annelies Vredeveldt at VU University Amsterdam and her team explain in their new paper in Applied Cognitive Psychology, there is a striking gap in the literature: “despite the frequency with which people use cannabis, there is almost no research examining its effects on eye-witness memory.”
Psychologists have proposed an explanation for why Ouija board users feel as though a spirit is moving the planchette (an ornate pointer) and spelling out messages. It is based on the idea that two (or more) living users unwittingly take turns at controlling the planchette, cooperating implicitly to create a message that starts out random but becomes more predictable as the number of meaningful options decreases.
“It seems that meaningful responses from the Ouija board are an emergent property of interacting predictive minds that increasingly impose structure on initially random events in the sessions,” Marc Andersen at Aarhus University and his colleagues explain in their open-access paper in Phenomenology and the Cognitive Sciences.
People who’ve had an out-of-body experience (OBE) report that their conscious awareness shifted outside their physical body – often upwards, so they felt like they were floating above their own head. It’s thought that OBEs occur when the brain fails to properly integrate data from the different senses, including vision, touch, proprioception (the sense of where the limbs and other body parts are located in space) and from the vestibular system (organs in the inner ear that monitor head orientation, balance and motion).
Previous research has mostly focused on the role of vision and touch – for example by triggering the illusion of viewing one’s own body – but the vestibular system has largely been neglected. If it does play an important role we should expect that problems with the vestibular system – which often present as feelings of dizziness – lead to OBEs, but do they?
Historical case studies suggested that they might. And now, published in Cortex, the first systematic study of patients referred to a neurological specialist because of dizziness has found that they can.
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.
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.