Psychology Blog

Apologies if updates are a little irregular, as I’m currently on my way back to the UK for a three week visit. This is largely because I’ve been asked to speak to the ‘All-Party Parliamentary Group on Scientific Research in Learning and Education’ about the evidence for whether computer games are damaging kids’ brains. I kid you not.

I shall also use the opportunity to catch up with the fantastic research group I’m associated with at the Institute of Psychiatry, but I’ll largely be sleeping on sofas, floors, buses, park benches and the like, so do forgive any irregularity or incoherence (although regular Mind Hacks readers seem quite well accustomed to both by now, and for some of you, I suspect it’s part of the attraction).

More here:
Back to blightly

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

There are numerous forms of body distortions and out-of-body experiences reported in the neurological literature but this is the first case I’ve found of someone who experienced tics that seemed to occur in external objects.

The report was published in the journal Neurology in 1997 and concerns a man with Tourette’s syndrome, a condition of persistent tics.

These more commonly appear as almost irresistible repetitive movements that the person feels compelled to complete, but occasionally they can appear as what are known as ’sensory tics’ which are repetitive sensations such as feelings of pressure, tickle, warmth, cold, or other abnormal sensation in skin, bones, muscles, and joints.

In this case, however, the sensations felt as if they were appearing in external objects:

A 34-year-old man dated the onset of his symptoms to age 5 when he developed a compulsion to bite down on cups and glasses. The drive was so irresistible that he once shattered a glass in his mouth. He later began having painful repetitive neck extension and shoulder shrugging. During childhood, he first noticed itchy or pressure sensations, usually deep in a joint, but sometimes on the skin, in his hands, feet, and arms. The sensations eventually spread. For a period of time, the inside of his knees and ankles were particularly affected and the sensation could only be relieved by banging his ankles together. Noises including grunts, sniffs, and loud shouts began during early adolescence. A period of coprolalia was present briefly. The tics came to involve the entire body. He had associated difficulty concentrating, compulsions, and obsessions. He was given a trial of clonidine without relief. He was never tried on other medications.

The patient characterizes his motor tics as voluntary movements performed in response to the “itchy” feeling. Although he can partially suppress tics in any given location, suppression enhances the feeling that he must move another body area. He frequently has the urge to repeat what others say to him but can usually suppress it. Beginning during childhood and persisting through adulthood, the patient noticed that the itchy sensations preceding motor tics could arise in other people or in objects.

The extracorporeal sensations are associated with the need to scratch or touch the itchy item in a particular way. External sensations most frequently arise in angles, corners, and points of objects such as elbows, the edges of tables, or the edge of his computer screen. Out-of-body sensations are more likely if the patient is touching an object but can also arise without direct contact. When younger, the patient would act on the accompanying urge and would scratch his sister’s elbow. He is able to resist touching other people.

Disembodied sensations are not uncommon after neurological difficulties (for example, a recent case study of a person with epilepsy reported a feeling of complete disembodiment) and can even be induced in you and me, as the ‘rubber hand illusion‘ demonstrates.

In this case, however, it isn’t clear exactly how the Tourette’s syndrome is triggering the feeling that the sensations appear in other objects, although it does suggest that our self-other boundary is not as iron-clad as we sometimes like to believe.

Link to PubMed entry for case study.

Read the original here:
The disembodied tic

Go Cognitive is an awesome free video archive of interviews and discussion that aims to explain some of the core topics in cognitive neuroscience.

It’s a project of the University of Idaho who’ve managed to convince some of the leaders in the science of the brain to talk about their work.

There are videos on fMRI, neuroplasticity, attention and neurological problems to name but a few, and there’s even a talk on psychology and stage magic.

The website also has a demo section that demonstrates some of the principles in action.

My only complaint is that you can’t download the videos, they can only be streamed, but nevertheless they remain a fantastically produced high quality series. Bravo.

Link to Go Cognitive videos (thanks Peter!).

Read more:
Go Cognitive guide to the brain

Every year the US Army holds an annual conference called the “Mad Scientist Future Technology Seminar” that considers blue sky ideas for the future of warfare. Wired’s Danger Room discusses the conference and links to an unclassified pdf summary of the meeting which contains this interesting paragraph about ‘neuro-cognitive warfare’:

In the far term, beyond 2030, developments in neuro-cognitive warfare could have significant impacts. Neuro-cognitive warfare is the mashing of electromagnetic, infrasonic, and light technologies to target human neural and physiological systems. Weaponized capabilities at the tactical level will be focused on degrading the cognitive, physiological, and behavioral characteristics of Soldiers. Its small size and localized effects will make it ideal for employment in urban areas. Such technology could be employed through online immersive environments such as 2d Life or other electronic mediums to surreptitiously impact behavior without the knowledge of the target.

I presume ‘2d Life’ refers to Second Life, but I could be wrong.

The first part is discussing the conventional development of warfare technology designed to target the nervous system, which is a long-established military tradition that has included weapons such as the rock, the poison-tipped arrow, the nerve gas shell and a new generation of hush-hush electromagnetic weapons.

The second part is a little more interesting, however, it implies that a certain form of stimulation embeddable in a popular game or internet service (I think they’re too shy too to say porn) might reduce cognitive performance by only a fraction, but when considered over a whole army, it could make a difference to the overall fighting force.

The scenario is a little bit science fiction (Snow Crash anyone?) but is an intriguing possibility given that only a slight change would be needed in an individual to justify its effect if it could be distributed over a wide enough population.

For example, many priming studies have shown it is possible to influence behaviour just by exposing people to certain concepts.

In one of my favourite studies, exposing people to ideas about elderly people slowed their walking speed, while a more recent experiment found this effect could change action sequences as well.

Link to Danger Room coverage of ‘Mad Scientist Seminar’.
pdf of unclassified military summary.

View post:
Future neuro-cognitive warfare