Sunday, October 23, 2011

It's Been Done

I'm not the first to point out the absurdly-small sample sizes of social-science research. Tversky and Kahneman (seen via The Wall Street Journal) beat me to it by several decades.

On the other hand, their sample size was only 84. On the gripping hand, that might be a dividing line between social-science research that should be taken seriously and social-science research that should be regarded as tentative.

One more point: My usual reaction to reports of research on cognitive bias is to wonder why we don't see more research into the cognitive biases of psychologists. It turns out they've done such research, at least as far as the cognitive bias of believing in small samples is concerned. The problem is that it isn't as widely reported as first-order cognitive-bias research.

Has there been any research done on the cognitive biases of science reporters? (I wouldn't be surprised to find there has been such research and the reporters don't mention it … for obvious reasons.)

Saturday, October 22, 2011

Life, the Universe, and Everything

The great question of Life, the Universe, and Everything turns out to be “What was the sample size for the paper ‘Subcortical processing of speech regularities underlies reading and music aptitude in children’?”

Digression: The problem with small-sample research isn't that it is necessarily invalid. A small-sample paper might be about something real. One problem is that if it were about a real phenomenon we should expect it to be backed up by large samples and frequently it isn't. Another problem is that it is usually reported as something definitive and small-sample research is always tentative.

Wednesday, October 19, 2011

Do Neuroscientists Have This Fold?

According to an article in Discover, there's a fold in the brain that helps keep reality and imagination separate. After seeing the sample size involved:

Of the 53 people selected for the study, some had this fold on both sides of their brain, some had it on one side, and some had no fold.

I wondered what part of the brain is responsible for taking studies with small sample sizes seriously.

Monday, October 10, 2011

I Reject Information That's Based on Small Samples

According to scientists studying optimism:

In a study published October 9 in Nature Neuroscience, researchers at the Wellcome Trust Centre for Neuroimaging at UCL (University College London) show that people who are very optimistic about the outcome of events tend to learn only from information that reinforces their rose-tinted view of the world. This is related to 'faulty' function of their frontal lobes.


Nineteen volunteers were presented with a series of negative life events, such as car theft or Parkinson's disease, whilst lying in a functional magnetic resonance imaging (fMRI) scanner, which measures activity in the brain. They were asked to estimate the probability that this event would happen to them in the future. After a short pause, the volunteers were told the average probability of this event to occur. In total, the participants saw eighty such events.

This was mentioned in an article cited by John Derbyshire.

Friday, October 7, 2011

We Know Free Will Doesn't Exist …

… because of experiments on five subjects:

The recordable cerebral activity (readiness-potential, RP) that precedes a freely voluntary, fully endogenous motor act was directly compared with the reportable time (W) for appearance of the subjective experience of 'wanting' or intending to act. The onset of cerebral activity clearly preceded by at least several hundred milliseconds the reported time of conscious intention to act. This relationship held even for those series (with 'type II' RPs) in which subjects reported that all of the 40 self-initiated movements in the series appeared 'spontaneously' and capriciously. Data were obtained in at least 6 different experimental sessions with each of 5 subjects.

There's better data, though. Another study had 14 subjects:

Haynes and his colleagues imaged the brains of 14 volunteers while they performed a decision-making task. The volunteers were asked to press one of two buttons when they felt the urge to. Each button was operated by a different hand. At the same time, a stream of letters were presented on a screen at half-second intervals, and the volunteers had to remember which letter was showing when they decided to press their button.

I think this was the study I discussed here.

Tuesday, October 4, 2011

Transcranial Magnetic Stimulation

After noticing that two of the articles mentioned were about Transcranial Magnetic Stimulation, I started getting suspicious. So looked at a few more on Pubmed.

According to Excitatory repetitive transcranial magnetic stimulation induces improvements in chronic post-stroke aphasia.:

We enrolled 8 patients with moderate or severe aphasia >1 year after LMCA stroke.

Sample size 8.

According to Accelerated repetitive transcranial magnetic stimulation (aTMS) for treatment-resistant depression

Patients included 9 men, 5 women with a median age of 51 years (range 20–74 years).

Sample size 14.

According to Revisiting the Backward Masking Deficit in Schizophrenia: Individual Differences in Performance and Modeling With Transcranial Magnetic Stimulation:

Seventeen patients (5 female) were recruited from the New York State Psychiatric Institute (NYSPI) Schizophrenia Research Unit.

Sample size 17.

According to Ten sessions of adjunctive left prefrontal rTMS significantly reduces fibromyalgia pain: A randomized, controlled pilot study.:

We recruited 20 patients with fibromyalgia, defined by American College of Rheumatology criteria, and randomized them to receive 4000 pulses at 10Hz TMS (n=10), or sham TMS (n=10) treatment for 10 sessions over 2weeks along with their standard medications, which were fixed and stable for at least 4weeks before starting sessions.

Sample size 20.

According to Worry Facilitates Corticospinal Motor Response to Transcranial Magnetic Stimulation

The 21 participants were self-identified right-handed males who ranged in age from 18 to 38 years (M=20.33, SD=4.22).

Sample size 21.

According to A bi-directional assessment of the human brain-anorectal axis.

Cortical evoked potentials was assessed following electrical stimulations of anus and rectum with bipolar electrodes in 26 healthy subjects.

Sample size 26.

Finally, according to Noninvasive brain stimulation with high-frequency and low-intensity repetitive transcranial magnetic stimulation treatment for posttraumatic stress disorder.:

In this double-blind, placebo-controlled phase II trial conducted between October 2005 and July 2008, 30 patients with DSM-IV-diagnosed PTSD were randomly assigned to receive 1 of the following treatments: active 20 Hz rTMS of the right DLPFC, active 20 Hz rTMS of the left DLPFC, or sham rTMS.

Sample size 30.

I've looked at nine of these papers. By small-sample standards, I could publish something. By the way, are there any large studies on Transcranial Magnetic Stimulation?

Sunday, October 2, 2011

Analgesia for Freshmen

According to NCBI ROFL (I don't think they take this seriously either):

Two studies assessed whether playing video games would significantly distract participants from painful stimulation via a cold pressor test. In Study 1, participants (8 men, 22 women, M age = 18.5 yr., SD = 1.3) in an action-oriented game condition tolerated pain for a longer time period and reported lower pain intensity ratings than those in a nonaction-oriented game or a nongame control condition. No differences were found on scores of aggressiveness, competitiveness, or prior video game experience, suggesting that these factors play little role. In Study 2, participants (14 men, 13 women, M age = 19.7 yr., SD = 1.3) engaged in six video game conditions (action, fighting, puzzle, sports, arcade, and boxing) and a nongame control condition. Video game play produced an increase in pulse, which was greatest during the action, fighting, sports, and boxing games. Pain tolerance was greatest during the sports and fighting games. Thus, certain games produce greater distraction, which may have implications for the medical field as an adjunct to pain management.

Maybe this only applies if you're also given extra credit for a psychology class.

More Mesmerism

Magnets are again being used in a small sample study (seen via futurisms):

In the study, the researchers asked 49 female volunteers to take part in a study where they were asked to rate the attractiveness of 220 photographs of female faces, but they were allowed to change their ratings after seeing what others in the study had scored.

When Transcranial Electromagnetic Stimulation (TMS) was used to inhibit the activity of the neurons in the posterior medial frontal cortex, the participants did not change their ratings of the photographs so they were more in line with the rest of the group.

Even if this does pan out, I doubt if it will have much of an effect on society. After all, the people most likely to want to use this are the people who need it the least.

Didn't Mesmer Pioneer This?

According to a recent study:

Here, we show that when subjects can name the colour of presented objects correctly or incorrectly at their free will, the tendency to stick to truthful answers can be manipulated by stimulation targeted at dorsolateral prefrontal cortex.

According to the Guardian's summary:

Inga Karton and Talis Bachmann of the University of Tartu adopted a different and novel approach, by examining the natural propensity to lie spontaneously during situations in which deception has no consequences. They recruited 16 volunteers, and showed them red and blue discs, which were presented randomly on a computer screen. The participants were asked to name the colour of each disc, and that they could do so correctly or incorrectly at their free will.

How do we know the experimenters weren't influenced by magnets?

Saturday, October 1, 2011

They Can Make You Take This Nonsense Seriously

The latest news from psychedelic research (an apparent repeat from forty years ago) is that that they can make you more “open”:

In the test, 30 people had a mystical experience, as established by a set of psychological scales. On tests of major personality traits, their openness scores rose, suggesting a greater interest in imagination, aesthetics, feelings, ideas and values. The 22 patients who didn't have a mystical experience showed no change.

Worthy of an Ignobel Prize

One of the latest Ignobel Prizes was awarded for a study on the effects of a need to urinate:

The studies on pee pressure were conducted by two groups of researchers who found that the need to urinate affected decision-making by their experimental subjects. One group found that moderate stress seemed to focus attention on the tasks at hand, but the other group concluded that an extreme need to urinate reduced attention span and the ability to make decisions.

"When people reach a point when they are in so much pain they just can't stand it anymore, it was like being drunk," Peter Snyder, a professor of neurology at Brown University, told AP. "The ability to hold information was really impaired."

When I looked up the paper in question (located via Scientific American), I found (I added the bold):

Eight healthy young adults consumed 250 ml of water every 15 min until they could no longer inhibit voiding. Performance on standardized measures of cognitive function was measured at hourly intervals which were classified as baseline, when individuals reported an increase in the urge to void, a strong increase in the urge to void, an extreme increase in the urge to void and postmicturition.

Small Sample Watch No. 1

The first example (also on my main blog):

According to a new study at the University of St. Gallen seen by SPIEGEL, one contributing factor may be that stockbrokers' behavior is more reckless and manipulative than that of psychopaths. Researchers at the Swiss research university measured the readiness to cooperate and the egotism of 28 professional traders who took part in computer simulations and intelligence tests. The results, compared with the behavior of psychopaths, exceeded the expectations of the study's co-authors, forensic expert Pascal Scherrer, and Thomas Noll, a lead administrator at the Pöschwies prison north of Zürich.


Introducing Small Sample Watch

I have often been annoyed by breathless reports of studies by alleged “scientists” using pathetically-small samples that mainly serve to confirm standard prejudices. I am starting a blog dedicated to such studies. When I see a news report of one of these, I'll post a link and sometimes a quote.