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Encephalon #35 arrives November 7, 2007

Posted by Johan in Abnormal Psychology, Links, Neuroscience.
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The latest issue of Neuroscience blogging carnival Encephalon is now online over at Primate Diaries.

My two picks of the issue would be two stories on Autism: Not Exactly Rocket Science reports on an experiment that is consistent with the ever-controversial idea that autism is linked with a deficient mirroring system. Also, Medopedia explores some possible reasons why people with Asperberger’s, that is, high-functioning Autism, frequently experience sleep disorders.

It’s the socialising, not just the bingo: new take on brain training November 5, 2007

Posted by Johan in Applied, Cognition, Social Psychology.

Blogging on Peer-Reviewed Research

Brain training is everywhere these days. From the Nintendo DS phenomenon Dr Kawashima’s Brain Training to the Neuroscientist-endorsed Mindfit, it is suddenly obvious to everyone that giving your brain a proper workout is as important to warding off dementia as getting your pulse up a few times a week is to avoiding heart disease.

I confess to being skeptical. Will my brain really benefit if I suffer through a mind-numbingly tedious working memory task? I think it depends on what your alternatives are. If your alternative is to sit silent in front of the TV, I suspect you will benefit, but isn’t there some other, less boring activity that might also help your brain?

A paper by Ybarra et al (in press) suggests that the answer to that is yes, and the alternative is socalising. Ybarra et al combined correlational and experimental designs to arrive at this conclusion. First, they used questionnaire data to show a positive relationship between the number of social interactions and cognitive functioning. The relationship held for all age groups (24-96), while controlling for a range of other factors.

This is a nice finding, but since there is no experimental manipulation, it is just as valid to interpret the findings to mean that intelligent people socialise more. So Ybarra et al went a step further, and recruited participants for an experimental study.

Participants were randomly assigned to three groups, where each group spent 10 minutes carrying out their task: the social interaction group discussed a current political issue, while the intellectual group did reading comprehension and mental rotation tasks, along with a crossword puzzle. There was also a passive control group who simply spent 10 minutes watching Seinfeld.

In order to assess how these different tasks affected cognitive functioning, Ybarra et al estimated processing speed via a task where participants made same-different judgements about dots, and a working memory task, where participants were read sentences which they had to answer questions about, all the while keeping a section of the sentence in memory.

The table below gives the results.

While the scores for the social interaction and intellectual groups are similar, the passive control group appears to have fared worse. Indeed, significance testing revealed that on each task, the experimental groups did significantly better than the passive control group, while the social interaction and intellectual groups did not differ from each other.

It is worth noting that the intellectual task is quite similar to the type of tasks that brain training programs consist of. These results indicate that instead of suffering under Dr Kawashima, you might as well get into an argument over politics with a friend (The alternative and equally valid interpretation of the data is that watching Seinfeld rots your brain). Discussing politics might just be more fun in any case – Ybarra et al did ask the participants to rate the tasks, but found no significant difference in how much the participants liked their tasks. Still, I would argue that most people will choose a debate over a working memory task any day.

This study is quite inspiring in that a single 10-minute session of intellectual or social stimulation was enough to bring about significant differences in task performance. Furthermore, it really is a testament to the power of social interaction that the intellectual task group didn’t come out ahead, even though they had basically spent 10 minutes doing very similar tasks to the ones they were assessed with. However, a few caveats should be considered. First of all, although the intellectual task resembles actual brain training, they are not one and the same. I would love to see a direct comparison between something like Mindfit and the social interaction condition used here. Secondly, although I wasn’t entirely serious about the possibility of Seinfeld rotting your brain, the fact that performance was tested immediately following the 10-minute training session is potentially problematic. It may be that carrying out an activity, any activity, simply raises your overall awareness more than watching TV does. It would have been nice to see a re-test the following day. Finally, this test only shows an immediate effect. If social interaction is to be taken seriously as an alternative to brain training, more longitudinal studies are needed, where regular training over a longer time is used.

So to conclude, these results indicate that bingo isn’t only good for granny for this reason:

But also for this reason:

Ok, so this particular bingo game might not be to granny’s taste, but you get the point.

Of course, no one can sell you social interactions, so expect brain training business to continue as usual.

Ybarra, O., Burnstein, E., Winkielman, P., Keller, M.C., Manis, M., Chan, E., and Rodriguez, J. (in press). Mental exercising through simple socializing: Social interaction promotes general cognitive functioning. Personality and Social Psychology Bulletin.

Thanks to Flickr users monkey123, Keees, and aphrodite-in-nyc for fantastic pictures.

In Defense of Electroconvulsive Therapy October 30, 2007

Posted by Johan in Abnormal Psychology, Applied, Emotion.

Blogging on Peer-Reviewed ResearchThe TED talks website contains material for a hundred posts, but a video posted earlier today hits particularly close to home. In this talk, Sherwin Nuland, a surgeon turned writer, gives an authoritative and unexpectedly personal account of the history of electroconvulsive therapy (ECT), sometimes known as electric shock therapy. The talk is only about 20 minutes, and gets very interesting around the 7 minute mark where Nuland describes how ECT once saved his life, as he puts it.

If the general public could be accused of placing too much trust in antidepressant medication, the reverse is certainly true of ECT. Ask anyone about electric shock therapy, and they’ll conjure up horror stories, and associations with frontal lobotomy. This is unfair, since there is some evidence that ECT actually works for depression.

The research on this issue has produced mixed results and plenty of controversy, as reviews by Challiner and Griffiths (2000) and by the UK ECT Review Group (2003) outline. However, there is no shortage of positive findings, and this in itself is rather remarkable, when you consider the patients that receive it. Since ECT is considered rather drastic, it is only really considered for patients who are severely depressed, and who have failed to respond to antidepressants. In other words, ECT is usually only considered in cases with the worst possible prognosis, so the fact that it does seem to help at times is quite powerful in itself, given the probability of spontaneous recovery from such conditions. That being said, a read of the ECT literature is unsatisfying. Because ECT is viewed as such a dramatic intervention (even in the absence of evidence that it causes long-term harm), it has rarely been tested on “normal” depressives in random control trials.

As Challiner and Griffiths (2000) outline, a lot of the popular conceptions of ECT are untrue. It doesn’t cause massive spasms – muscle relaxants are administered. It is not going to be a traumatic experience, because you will be put under a general anaesthetic. Although bilateral administration of ECT has been associated with memory loss, this does not appear to happen with unilateral administration, where both electrodes are kept on one side of the head (as shown in the picture at the top).

There is another issue with ECT, which I think bothers practitioners than clients. In the case of antidepressants, we at least know how they work, although it is far from clear why boosting synaptic Serotonin levels should work, given the weak evidence for a lack of Serotonin in depression. With ECT, there are no convincing explanations for either the how or the why. Psychiatrists stumbled upon ECT in the happy days of wild experimentation that preceded Ethics Committees, without much of a theory. It is quite embarrassing that even to this day, we can say so little about what this treatment does, or indeed if it even does anything at all – a pertinent question given the claim on Wikipedia that 1 million people receive ECT each year worldwide.

If I ever developed a severe depression, I would try ECT before antidepressants. Unlike antidepressants, the effects of ECT can be instantaneous, and there are no long-term side-effects, nor any withdrawal symptoms when the treatment ends. Since the treatment is extremely safe when administered properly, there is really very little to lose.

Challiner, V., and Griffiths, L. (2000). Electroconvulsive therapy: a review of the literature. Journal of Psychiatric and Mental Health Nursing, 7, 191-198.

The UK ECT Review Group. (2003). Efficacy and safety of electroconvulsive therapy in depressive disorders: a systemic review and meta-analysis. Lancet, 361, 799-808.

Visual Cortex: A Schematic Map October 22, 2007

Posted by Johan in Neuroscience, Sensation and Perception, Social Neuroscience.
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I came across this figure in a review by Grill-Spector and Malach (2004). It condenses an already-dense 40-page review into a single figure, so I would have to write a post of similar length to explain it entirely in laymen’s terms. This may be one post to skip if you haven’t the slightest idea of visual perception.

Even if you know your vision, this figure isn’t entirely straightforward. Still, I think it serves as a useful reference for those dense vision papers. With one or two notable exceptions, vision scientists insist on ridiculous naming conventions (the motion sensitive area hMT+ being the case in point), so this might help you remember the plot.

This map is only schematic. However, it represents the rough relationships, as they stood in 2004. The areas are mapped onto the right hemisphere occipital lobe, which has been flattened so that the dark areas represent sulcii (grooves), and the light gyrii. The posterior-anterior axis is sort of bottom-left to top-right, so V1 is (predictably) at the very back of the brain, while the Parahippocampal Place Area (PPA) is on the ventral (bottom) side.Height in this picture represents hierarchy in the processing, as Grill-Spector conceives of it. In other words, the first area is V1, and then we move up the stairs to V2, V3, and so on.

The colours code specialization. In the early areas (V1-V3), this is represented by central versus peripheral mappings, where the cortical magnification factor ensures that the centre is largest, and the highest acuity. Helpfully, they are labelled P-D (down) for the superior end of each map, and P-U (up) for the ventral end (your retinal image of the world is upside down, and apparently the visual system has no need to reverse this representation in later areas).

In later areas, the areas are filled in with one colour, presumably for simplicity – Grill-Spector actually believes that these have some retinotopic organisation as well. The colours still reflect specialization though – we can see that areas such as the Fusiform Face Area (FFA) and the Lateral Occipital complex (LO) are based on central, high-acuity representations, while other areas such as the PPA are based on more peripheral, lower-resolution representations. The letters that are strewn over the areas are meant to approximate locations of sensitivity to certain object categories: places (Pl), objects (O), and faces (F).

Do note that the Superior Temporal Sulcus (STS) is treated as somewhat of a black sheep, placed out in the corner with no colouring or height. This is probably because it is relatively poorly understood. The STS responds to biological motion, such a Johansson figures (see a demo), but its activation also appears to be strongly modulated by the social significance of the stimulus. For instance, Pelphrey et al (2005) found that the STS response in normal controls was greater when a face looked away from an obvious object rather than when gaze was directed towards it, which suggests that the STS does more than merely detect biological motion. Interestingly, people with Autism failed to show the same modulation by expectation in the STS.

The poor understanding of the STS is in part because it responds so specifically to biological motion, which makes conventional retinotopy techniques impossible. Also, I suspect there is a deep-rooted fear in some vision scientists of anything that starts with “Social.”

Another thing to note is the chasm between the last V area and the STS. Presumably, the intermittent areas are also involved in vision, but we don’t know much about what they do yet.

Grill-Spector, K, and Malach, R. (2004). The Human Visual Cortex. Annual Review of Neuroscience, 27, 649-677.

Pelphrey, K.A., Morris, J.P., and McCarthy, G. (2005). Neural Basis of Eye Gaze Processing Deficits in Autism. Brain, 128, 1038-1048.

Hearing limitations, pt. 2: Distinguishing MP3 from CD October 16, 2007

Posted by Johan in Applied, Sensation and Perception, Social Psychology.
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As a continuation of the recent post on audiophiles, let’s look closer at how good we are detecting the compression in digital music formats.

Most music formats, such as MP3 or the AAC format used by iTunes, define the rate of compression as the number of bits that is used to encode each second of music. The standard bitrate, as used by the iTunes Music Store and elsewhere, is 128 kbit/s. Music geeks (myself included) tend to use slightly higher bitrates, while the proper audiophiles use lossless formats that compress the file without actually removing any information. Recently, Radiohead released their new album as a free download, only to experience some fan backlash for their choice of a 160 kbit/s bitrate. Critics bemoaned the fact that this was half as much as the 320 kbit/s rate that is used on the mp3s available for purchase on their website. By comparison, the bitrate of a normal audio CD is approximately 1411 kbit/s, so clearly a lot of information is removed.

But can you tell the difference? I dug out a few non-peer-reviewed sources to get an idea – if someone knows of peer-reviewed studies into this, I’d be interested to hear about them. The most serious source is probably this 1998 report from the international organisation for standardisation (PDF), which reports some evidence that participants could distinguish 128 kbit/s compression from the original, uncompressed source. Unfortunately, no tests were made above 128 kbit/s. More recent, but less rigorous tests have been reported by Maximum PC and PC World.

Maximum PC elected to report their results participant-by-participant, and with a sample size of 4, maybe that’s just as well. There isn’t enough data reported in this article to actually run a binomial or another significance test, but the overall conclusion seems to be that none of the testers did well at distinguishing 160 kbit/s from the original source.

PC world’s test actually contains some descriptives, and used a sample size of 30. However, they used some fairly obscure ways of reporting their results. Clearly, in a case like this one, the optimal method is to ask the participants to guess which file is the mp3 and which is the cd, and run a number of trials without feedback. With this approach, you can easily assess whether performance is over the level of chance (50%) for each bitrate. With this in mind, here are their results:

The percentages represent the proportion of listeners who “felt they couldn’t tell the difference” – once again, this measure is far from ideal. While we have no idea which of these differences are significant, the trend is that the differences in ratings flatten off: there appears to be no difference in quality between 192 kbit/s and 256 kbit/s, and in the case of MP3s, no real difference between 128 and 192.

These studies aren’t exactly hard science, they do seem to indicate that those complaining about Radiohead’s 160 kbit/s bitrate wouldn’t necessarily be able to distinguish it from CD quality, let alone a 256 kbit/s mp3. This illustrates the human tendency to overestimate our own perceptual ability – if we know that two things are different, we will find differences, imagined or otherwise. Blind testing is the only way to establish whether a genuine difference in sound quality exists, yet, this is very rarely done.

If you want to test your own ears, try these examples. With the above in mind, it would be best to get a friend to operate the playback, so that you can’t tell from the outset which file is which. If you run a large number of trials, you can also look up whether your performance is above chance in this Binomial probability table. In psychology, .05 is the commonly accepted p value, so as an example you would need to get 15 out of 20 trials correct for your performance to be significantly better than chance at this level.

Update: Dave over at Cognitive Daily has answered my prayers by carrying out a nicely designed test of performance at discriminating different bitrates. In a nutshell, his results confirm the ones reported here – Although there participants rated the 64 kbit/s tracks as significantly poorer in quality, no differences appeared between 128 and 256 kbit/s. Read the complete write-up here.


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