Psychology Blog

… in Miami, this Friday and Saturday, organized by past guest blogger Brad Cokelet. Schedule of speakers:

Friday, March 12 (U of Miami, Learning Center, Room 192):

10:30-12:00, Dan Haybron, “Adventures in Assisted Living”
1:35-3:05, Eric Schwitzgebel, “The Moral Behavior of Ethics Professors”
3:15-4:45, Alfred Mele, “Autonomy and Neuroscience”

Saturday, March 13 (U of Miami, Memorial Bldg, Room 192):

10:30-12:00, Valerie Tiberius, “In Defense of Reflection”
1:30-3:00, Blaine Flowers, “Evolution, Sociality, and Eudaimonia: An Aristotelian Integration of Human Nature and Goods”
3:20-5:25, round table discussion

It should be good fun! If you’re in south Florida, you might consider checking it out. For further info, contact Brad Cokelet at University of Miami.

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Conference: Experimental Philosophy and the Ethics of Autonomy

Several perennially fascinating questions arise in the study of humankind: What makes us so different from other animals? Was there some turning point or specific development that marks the emergence of uniquely human behavior? In other words, how did we become human? A recent workshop at Arizona State University, “Origins of Human Uniqueness and Behavioral [...]

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The making of humanity

The San Francisco Exploratorium is the Mind Hacks of science museums - every exhibit is hands on, giving you the chance to experiment with and experience for yourself scientific principles.

Obviously, one of my favourite exhibits was a psychology demonstration, one based on a classic visual illusion known as the “Ames’ Room”. We’ve a small model of this in Sheffield, which I use when teaching PSY101, but the Exploratorium’s “distorted room” is full size demonstration of the effect. Here’s me and a friend in the room:

Notice anything odd? We’re the same size in reality, but I (on the right) look significantly larger.

The illusion takes advantage of the unavoidable principle that size and distance are confounded - known as “Emmert’s Law“. It is Emmert’s Law that means that big things far away can look the same size as small things near by. Our brain makes assumptions about how far away things are and uses these to inform our impression of size. The distorted room is built so that, from one perspective only, the two sides of the room look an equal distance away. In fact, the corner on the right is far closer to the viewer (the camera in this case) than the corner on the left. Because I really am nearer the camera I make a larger image on the retina (take up more pixels on the camera), but because the brain assumes that I am the same distance away as my friend on the left the only conclusion that my visual system can draw is that I must be much larger than him.

Normally your visual system isn’t fooled about depth - clues in the scene, the difference between the image on your two eyes and movements of your head can all help reveal how far away different parts of the scene are. The distorted room removes some of these clues by forcing you took look at the room with one eye from a fixed point, and other clues it deliberately tricks (like the shape of tiles on the floor, which look the same from left to right, but actually get smaller, because the tiles on the right are closer).

The confounding of size and distance is the same principle behind illusions like this:

The effect only works because it is in a photograph (so from one perspective) and because the relatively featureless desert removes other clues to the depth of objects.

So the next time you close one eye and line up someone in the distance between your thumb and forefinger while muttering “I’m crushing your head!“, think of Emmert’s Law. And if you are in San Francisco, visit the Exploratorium!

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In the Exploratorium’s distorted room

Cannabis smokers often report that when stoned, their thoughts have a free-wheeling quality and concepts seem connected in unusual and playful ways. A study just published online in Psychiatry Research suggests that this effect may be due to the drug causing ‘fast and loose’ patterns of spreading activity in memory, something known as ‘hyper-priming’.

Priming is a well studied effect in psychology where encountering one concept makes related concepts more easily accessible. For example, classic experiments show that if you see the word ‘bird’ you will react more quickly to words like ‘wing’ and ‘fly’ than words like ‘apple’ and ‘can’ because the former words are more closely related in meaning than the latter.

In fact, it has been shown that the more closely related the word, the quicker we react to it, demonstrating a kind of ‘mental distance’ between concepts. Think of it like dropping a stone into a pool of mental concepts. The ripples cause activity that reduces in strength as it moves away from the centre.

‘Hyper-priming’ is an effect where priming happens for concepts at a much greater distance than normal. For example, the word ‘bird’ might speed up reaction times to the the word ‘aeroplane’. To return to our analogy, the ripples are much stronger and spread further than normal.

The effect has been reported, albeit inconsistently, in people with schizophrenia and some have suggested it might explain why affected people can sometimes make false or unlikely connections or have disjointed thoughts.

As cannabis has been linked to a slight increased risk for psychosis, and certainly causes smokers to have freewheeling thoughts, the researchers decided to test whether stoned participants would show the ‘hyper-priming’ effect.

The experiment used a classic ‘lexical decision task‘ where the volunteers are shown an initial word (’time’) and then after a short gap are shown a nonsense word (’yipt’) and a true word (’date’) at the same time and have to indicate as quickly as possible which is the real world.

The experimenters altered how related the initial word and true word were to test for the semantic distance effect, and also varied the gap between the initial word and the test to see how long the priming effect might last.

Volunteers who were under the influence of cannabis showed a definite ‘hyper-priming’ tendency where distant concepts were reacted to more quickly. Interestingly, they also showed some of this tendency when straight and sober .

Cannabis also had the effect of causing temporary psychosis-like distortions as would be expected from a psychedelic drug, but the smokers did not make more errors and were not more likely to report psychosis-like symptoms when sober, suggesting the effect was not due to general mental impairment and couldn’t be explained by underlying tendency to mental distortion.

Although the debate is not completely settled, there is now good evidence that cannabis causes a small increased risk for developing schizophrenia particularly when smokers start young. In fact, additional evidence on this front was published only this week.

The researchers discuss the possibility that long-term smokers who spend a lot of time in a chronic ‘hyper-primed’ state might make psychosis more likely by loosening the boundaries of well-grounded thought, although exactly how cannabis raises the risk of psychosis, and indeed, how exactly it affects the brain, is still not understood well-enough to make a firm judgement.

Link to PubMed entry for cannabis ‘hyper-priming’ study.

Originally posted here:
How cannabis makes thoughts tumble

A brain scanning technology called MEG is being used to track the function of unborn babies’ brains as they grow inside the womb until after they’ve been born.

The full name for MEG is magnetoencephalography and it works by reading the magnetic fields created by the electrical signalling in the brain.

One of the advantages is that it can be used at various angles, doesn’t require the person to be in a cramped space, and is less sensitive to movement, so is ideally suited to scanning babies.

This includes unborn babies and with a bit of modification, as illustrated in the picture, researchers can pick up signals from the fetal brain in response to flashes or light or sounds.

We discussed the use of fMRI to scan the fetal brain previously, but this is a remarkable study that scanned the brains of babies inside the womb, every two weeks from week 27 until delivery, and then once after they were born.

Clearly, unborn babies are not the best at doing tasks set by experimenters, but there are various tests that just require the individual to experience changes in what’s presented to them.

One is called the auditory oddball task, where a series of tones are played that can either be similar (’beep beep beep’) or can have include an ‘oddball’ (’beep beep boop’). The brain is very good at picking out differences and the oddball is known to reliably trigger brain signals related to detecting changes.

This was the exact task used with the babies and the researchers looked to see if they could pick out a brain reaction to the ‘oddball’.

They found that they could detect this response 83% of the time in unborn babies, and that the reaction to the ‘oddball’ increased in speed throughout pregnancy. The newly born babies showed the response every time without fail.

This is an impressive finding as it shows how the brain development of the unborn child can be tracked over time with a brain scanner.

In a recent review article that discusses the development of this technology, the same group of researchers suggest that these and similar techniques could help track how different conditions in the mother affect the developing brain and even how the brain begins to develop its understanding of speech sounds before birth.

Link to PubMed entry for MEG study of developing fetus.
Link to PubMed entry for review article on fetal MEG.

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Tracking the unborn brain into childhood