We all see things that are not there, every now and again.

Particularly things that are on our mind. For example, if you're thinking about someone, you're increasingly likely to see, or think to have seen, that someone out on the street. This is because our perception is biased by our expectations. Put differently, we try to fit what we see into mental templates.

A recent study by Smith and colleagues shows this in a new way, which I think is kind of cool. In this study, participants watched patches of completely random noise, like static on television. But the participants were tricked. (Yes, they keep falling for it.) They were told that on half of the trials a face was hidden in the noise. And they were instructed to indicate on every trial whether they had seen a face or not.

The analysis that Smith and colleagues performed was quite simple. They took the average of the patches of noise on which the participants indicated that they had seen a face, and subtracted from this the average of the non-face patches. If the participants had just been randomly pressing keys, this procedure would have led to a uniformly black image. After all, the average of lots of noisy patches is uniformly grey. And grey minus grey is black.

But this is not what happened! Out of the noise emerged clear (well, let's say reasonably clear) outlines of faces. Apparently, the participants tried to match their template of what a …

In the animation below, it appears as though Mario is jumping vertically and the Koopa shell is gliding horizontally. But actually, as you can clearly see when the background stops moving, Mario and the shell both move in circles!

(This illusion is a variation on Stuart Anstis' Flying Bugs illusion.)

So what's going on here? The first thing to note is that, although Mario and the shell are following a similar circular trajectory, they are in antiphase. Which is just a fancy way of saying that when Mario is at 12 o'clock, the shell is at 6 o'clock. The background image also follows a circular trajectory. But it goes clockwise, so the rotation of the background is opposite to that of Mario and the shell.

The crux of the illusion is that the rotations of the three elements (Mario, the shell, and the background) are aligned in a very specific way. The horizontal component of the background motion is the same as Mario's: When the background moves to the right, so does Mario. Mario's horizontal movement is therefore cancelled out, and consequently Mario appears to move only vertically. Conversely, the vertical component of the background motion is matched to that of the shell. Therefore, the shell appears to move only horizontally.

This illusion is a very salient demonstration of how we use background information to make judgements about positions and movement. We don't perceive the actual movement of Mario and the shell, we perceive their movement relative to the background …

The prestige of an academic journal is determined largely by its impact factor. This is a somewhat odd measure of how often, on average, a paper in a journal is cited in other academic publications. To give you a rough idea: In 2010, Nature and Science, the two most famous academic journals, had impact factors of 36 and 31, respectively. A decent journal in the field of cognitive science would have an impact factor of, say, 3. And when a journal's impact factor drops below 1, things get dodgy.

Editors will try to boost their journals' impact factor, of course. This is good, for the most part, because it provides editors with an incentive to create a decent journal that publishes good science. But as Wilhite and Fong show in a recent edition of Science, there's a dark side as well: Coercive self-citation.

Wilhite and Fong distributed a survey under academics from various disciplines. In this survey, respondents indicated whether, when submitting a manuscript to a journal, they had ever been asked by the editor to include useless citations to other papers from that same journal. The motivation for the editor to do so is obvious: Additional self-citations raise the journal's impact factor. Wilhite and Fong give a strikingly blatant example of such a request made by an editor to an author:

"You cite Leukemia [once in 42 references]. Consequently, we kindly ask you to add references of articles published in Leukemia."

Clearly, this seemingly friendly question implies something that …

A recent paper in PLoS Biology has caused a minor stir. In this paper, Pasley and colleagues show that you can find out which word a person has just heard by decoding activity in a specific part of the human brain. This is mind reading, in a sense. And it's therefore not surprising that some are talking about the Orwellian implications of this study, or speculate about the possibility of decoding inner speech in the same way.

But what did they Pasley and colleagues actually do? It's quite a technical paper, so you will have to forgive me if I have missed a few details. But the general idea behind the study is straightforward.

Pasley and colleagues recorded directly from the brain of human participants. Normally this is not possible, because intra-cranial recordings are highly invasive. You have to open up the skull in order to attach recording equipment to the brain. Few participants will agree to this, and even fewer ethical commissions will condone it. But sometimes, when a willing participant is about to undergo brain surgery (usually for a severe form of epilepsy), scientists get the unique opportunity to do this kind of experiment with humans.

The brain area that Pasley and colleagues recorded from was the posterior superior temporal gyrus. This area is traditionally thought of as a midway station in the transformation from low-level acoustic information (sounds without meaning attached to them) to conceptual representations (the meaning of words, concepts, etc.).

The neurons in this brain …

I just came across an inspiring blog post by the mathematician Tim Gowers. In this post, which I invite you to read, he calls for a boycott of Elsevier. I share his discontent and so, I hope, will you.

Elsevier is one of the largest academic publishers, and is notorious for charging extremely high prices. This places a considerable financial burden on publicly funded academic institutions, who are, for various reasons, practically forced to buy Elsevier content. Elsevier has also engaged in other dubious practices, such as actively supporting a bill against open access publishing.

Elsevier is not alone in this. In fact, not too long ago there was a similar outrage over price increases by the Nature Publishing Group. But, as Gower points out and as you can read in the overview by White and Creaser, Elsevier is quite simply the worst.

There is now a website, The Cost of Knowledge, which calls on scientists to declare publicly that they will not support Elsevier by publishing in or reviewing/ editing for any of the Elsevier journals. I must admit that, at first, I was a little hesitant to sign this, because preventing myself from publishing in Elsevier journals is not necessarily a booster for my (very young) career. But I have decided that I will sign nevertheless: There are plenty of good, open access alternatives in my branch of research: any of the PLoS journals, Journal of Vision, BioMed central, Journal of Eye Movement Research, to name but a …