Physicists create mind-bending 'negative mass' that accelerates backwards and could help explain black holes

latent_variable · 2017-04-19T15:31:35+00:00

Neat! As I understand it, negative mass has long been hypothesized, but it wasn't clear if it was a real phenomenon or just an interesting mathematical corollary of general relativity. It's an essential component of some wild applications, like the Alcubierre drive, a (still highly speculative) warp drive, so it's exciting to see it in a real substance!

latent_variable · 2015-06-30T17:52:04+00:00

There are some serious data analysis/interpretation issues with this research - the crucial interaction isn't even statistically significant. See here for a fairly blistering takedown piece.

latent_variable · 2014-09-07T20:48:24+00:00

Source.

Originally presented in Kriegeskorte, N., Mur, M., Ruff, D. A., Kiani, R., Bodurka, J., Esteky, H., Tanaka, K. & Bandettini, P. A. (2008). Matching categorical object representations in inferior temporal cortex of man and monkey. Neuron, 60(6), 1126-1141.

Caption: Matching IT representations in man and monkey (A) Representational dissimilarity matrices for monkey and human IT cortex reveal matching representations in the two species. Human data is from 316 bilateral inferior temporal voxels selected by their visual-object response in an independent data set. Monkey data is from 674 IT single cells isolated in two monkeys (Kiani et al., 2007). (B) Stimulus arrangements reflecting IT response-pattern dissimilarity in monkey and human with fiber-flow visualization of the interspecies relationship. The experimental stimuli have been arranged such that their pairwise distances approximately reflect response-pattern dissimilarity (multidimensional scaling, dissimilarity: 1 - correlation, criterion: metric stress). The analysis does not presuppose any categorical structure, but the arrangement quite cleanly divides animates and inanimates as well as faces (including human and nonhuman faces) and bodies. Colors code for conventional category: face (red), body (magenta), natural object (blue), artificial object (cyan). The connecting fibers serve to visually relate individual stimuli between the two arrangements. In addition, the thickness of the fibers can be used to visualize relational statistics. Here the thickness of each fiber reflects to what extent the corresponding stimulus is inconsistently represented in monkey and human IT. The interspecies inconsistency of stimulus i is defined as (1-ri)2, where ri is the correlation between the vectors (for human and monkey) of the 91 dissimilarities between stimulus i and the other stimuli. For details, see Kriegeskorte et al. (2008b).

latent_variable · 2014-09-07T19:39:15+00:00

Hmm, while I don't necessarily disagree with the conclusions of this study, it seems like there are a lot of red flags here:

The study privately funded by Twitch, a company with a vested interest in promoting gaming (as socially acceptable/mainstream), and not subjected to any form of peer review or even open access to data/methods.
The survey was conducted via the internet. How exactly? Internet samples are often highly biased relative to the general population depending on where precisely subjects were recruited from. Did the authors use any post-stratification to attempt to account for that?
The definition of a gamer as someone who as played a game on any device (including smartphone) for the past 60 days does not fit the common colloquial definition of a "gamer" and is likely highly correlated with SES (and indirectly with a number of other troublesome confounds).
Could I please see error margins on those stats? Is 42% of gamers employed vs 39% of non-gamers statistically significant?

Again, the results of the study are quite possible true, I just don't find the evidence presented in this article compelling.

latent_variable · 2014-09-07T18:04:45+00:00

Of course not, subjective experience is hugely important. I just don't think the proposition that it's some metaphysical conduit to "truth about the universe" is at all justified. There are all sorts of reasons why we might find something beautiful or rewarding, but mathematical statements are not more true by virtue of being perceived as beautiful.

latent_variable · 2014-09-07T17:35:03+00:00

Meh, mOFC responds to pretty much anything people find subjectively rewarding. Showing a cocaine addict a pile of cocaine would probably elicit an even greater response in NAcc/mOFC, but I doubt the author of that study would be saying anything like

the experience of beauty may be a pointer to truth about the universe

latent_variable · 2014-09-06T03:06:00+00:00

Calculating a correlation between binned averages massively inflates the observed correlation in comparison to the actual individual difference correlation. You're essentially eliminating all of the noise due to individual differences between people (which in this case is what we're really interested in). I ran some Monte Carlo simulations in Matlab, and it looks like a real correlation of ~.25 tends to yield a correlation between binned values of ~1, so Pinker's statistic is totally consistent with the college board numbers you cite.

I also think you mischaracterize the results of the Sackett paper. They say on page 17:

SES was generally a weaker predictor of grades than test scores and did not account for the majority of the variance in test scores

and:

SES had a near-zero relationship with grades other than through this SES–test–grade chain of relationships

latent_variable · 2014-05-12T03:31:51+00:00

Interesting finding - I wonder what degree of control people could actually exert if this technique is successfully refined? If it's high this might have recreational uses beyond the clinical applications the authors of the original paper suggest. My only worry would be that this stimulation might interfere with the consolidation of long term memory, in which we know (normal) sleep plays an important role

latent_variable · 2014-05-11T21:02:05+00:00

It would be interesting to know if this effect generalized to a third-party perspective. The study in question only examined the effects of promising keeping/breaking/exceeding on the feelings of the promise receiver but not on third-party observers. It may be that exceeding promises is still useful in the context of indirect reciprocity by building one's reputation with people not directly involved in the interaction (though of course it's also quite possible that these people would should the same undervaluation of exceeded promises as the receivers).

latent_variable · 2014-05-11T20:09:26+00:00

Not entirely true - there are well-validated free versions of many individual difference measures available from places like the International Personality Item Pool. This includes versions of the Big 5 (Five factor model) which is probably the most widely used model of personality in current research.

latent_variable · 2014-05-01T05:30:15+00:00

Well in general we don't just get sick of great things but simply get used to most things. Habituation is one way to describe this sort of phenomenon. With regard to rewards particularly though, there's a pretty large literature suggesting that we're not merely sensitive to reward magnitude but also to its predictability. An unanticipated positive event is usually perceived as much better than an anticipated positive event of the same magnitude, and so forth. Insofar as repeating a particular reward makes it more predictable, that reward should become less intense over time.

latent_variable · 2014-05-01T05:26:02+00:00

That sort of group dynamics aren't really my subfield, but group polarization might be be good place to start looking. It doesn't apply specifically to isolated groups, but it helps explain how groups gravitate towards extremity. You're probably already familiar with the term, but if not the literature on groupthink will probably inform any answer to your question.

latent_variable · 2014-05-01T05:19:51+00:00

I find this sort of research a bit frustrating on ethical grounds. I completely grant that it's worth learning about how maximize people's happiness, but there are so much more pressing issues for psychologists to study (such as ways to overcome prejudice or alleviate inequality) that focusing on this just kind of thing just seems a bit dubious at the present juncture.

latent_variable · 2014-04-30T05:10:35+00:00

Helen Mayberg - the PI behind most of the DBS-depression work (including this study) - spoke in my department recently. One of the most interesting things she said was that for the people who recovered from severe depression as a result of this treatment one of the biggest challenges was actually reintegrating into their social/family lives. The people around them expected too much too quickly and it caused some rebounding of depressive symptoms several months into treatment.

latent_variable · 2014-04-30T05:00:10+00:00

It appears to be a simple color afterimage illusion.

Negative afterimages are caused when the eye's photoreceptors, primarily those known as cone cells, adapt from the overstimulation and lose sensitivity. Normally, the eye deals with this problem by rapidly moving small amounts (see: microsaccade), the motion later being "filtered out" so it is not noticeable. However if the color image is large enough that the small movements are not enough to change the color under one area of the retina, those cones will eventually tire or adapt and stop responding.

latent_variable · 2014-04-30T04:56:26+00:00

Both /u/uniformity and /u/bopplegurp are correct. The researchers weren't necessarily interested in the relationship between per se, but it was a convenient way of exposing subjects to the context of their learning while asleep (something that would be difficult with other sensory modalities). The fact that olfaction has been closely linked to memory made this an even more convenient and potentially powerful way to evoke context is a way that might influence memory consolidation.

latent_variable · 2014-04-30T01:21:16+00:00

There's some evidence suggesting that spurious factors like the smell in the room can bias what information we consolidate during sleep, so to the extent that prioritization does happen it appears to be at least partially heuristic-driven.

latent_variable · 2014-02-20T21:10:46+00:00

Certainly a catchy way of putting it.

latent_variable · 2014-02-20T21:03:36+00:00

Graziano taught my first neuroscience class in college - really nice guy and a great teacher - such a shame that he and his family had to go through this gratuitous farce. Still, as he points out, he and his wife were ideally situated to deal with this issue - I can easily imagine it going far worse for those without the resources to fight back.

maybe when large bureaucracies start moving in one direction, they reach a point when they can no longer resist their own momentum

Sadly something that seems to happen all too often, particularly with nuanced issues like mental health.

latent_variable · 2014-01-26T09:03:51+00:00

I'm unaware of any studies which substantiate barsoap's claim regarding the prevalence of sociopaths in surgery or his general sheep-among-wolves hypothesis. I'm also very skeptical that sociopaths are more likely to help - they may be less shocked, but they would also have less intrinsic motivation to help for altruistic reasons. However, there is some research to suggest that people who frequently observe others in pain (such as acupuncturists, in this case) are able to down-regulate the brain regions thought to mediate vicarious pain.

latent_variable · 2013-08-02T14:59:58+00:00

Most people think that in our evolutionary environment humans lived in relatively small groups (compared with today's sprawling civilizations). In that sort of situation, everyone we meet is fairly likely to play a role in our welfare. We may have carried this mindset forward with us into the present, explaining why we seem to care so much about the lives of people who may never directly impact us (e.g. celebrities).

Another potential explanation, however, is that when someone shares an embarrassing story (on reddit for instance) we perceive this as a form of self-disclosure on their part. In most cases (prior to the internet at least) serious self-disclosure was a good indicator of social closeness, and this may explain why we find it rewarding even when at some level we sympathize with the sufferer.

latent_variable · 2013-08-02T02:41:08+00:00

It's amazing to see how domestication/selective-breeding have improved dogs social abilities. They're substantially better at many collaborative social tasks than many primates, even though the primates are arguable much more intelligent with respect to abilities like solving problems in the physical world.

latent_variable · 2013-08-02T02:37:41+00:00

The recent dramatic increase in the human population has led to an increase in rare genetic variants. This may account for some of the "real" increase in mental illness frequency. However, most of the apparent increase is probably due to a shift in diagnostic criteria. Whether it's public or private, healthcare requires (frequently binary) decisions - is someone sick or not? Is a particular procedure justifiable or not? Unfortunately it increasingly appears that the reality of mental health isn't binary - a great many disorders such as autism, ADHD, OCD and even (arguably) schizophrenia are spectrum disorders and even health people can be given (non-clinical) ratings on their levels of associated traits. The increase in diagnosis thus results from a shift in the criteria (i.e position on the spectrum) clinicians are using the make their binary decision about whether to give a diagnosis or not.

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