Criminal profile
In her article on the science of criminal profiling (28 August, p 42), Laura Spinney quotes studies that play the game of testing the profilers’ predictions. However, the serious scientific question in criminal profiling is: what reliable inferences can be made about criminals from how, where and when they commit crimes?
As with all scientific inferences, the task is to determine under what conditions any relationships hold. This task is faced by anyone trying to understand and predict human behaviour, not just those seeking to advise the police.
To further the utilisation of psychology in criminal investigations, the field of investigative psychology has been developed, which should avoid the pitfalls and myths associated with “profiling”. The field deals with the challenges of how to use the information available to detectives, developing inference models and using the resulting conclusions to aid decision-making. Many studies in investigative psychology have now taken place, and the field has an established academic journal and a major textbook. It is a pity that New 杏吧原创 should focus on criticisms of the out-of-date concept of “offender profiling” rather than reviewing what is now known and still unknown in investigative psychology.
Brain flip
In her article “Why your brain flips over visual illusions”, Jessica Griggs highlights work suggesting that the superior parietal lobe (SPL), an area of the brain known to control attention and process three dimensional images, may control switching our conscious attention from one possible image to another (4 September, p 14). She could have taken us a step closer to understanding what drives this switching by alluding to David Robson’s earlier article on vision (28 August, p 30).
Robson discussed various lines of evidence suggesting that the brain processes different features of the visual field in different areas, finally stitching them together in the posterior parietal lobe (PPL).
The primary purpose of any vision system is to monitor the visual field for threats or opportunities. It is not an efficient use of resources to always process the whole visual field to the maximum possible level of detail, so it seems reasonable to suppose the brain has mechanisms which decide what to focus its power on.
For example, if you try to count the number of each type of utensil in a messy cutlery drawer, you can almost feel your brain reinterpreting the same view as you switch from counting forks to knives. Perhaps your SPL is performing gymnastics while trying to match shapes with the perfect image of forks or knives in your mental library? And perhaps it is the PPL that has prepared the possible interpretations in your mental library.
As speed is of the essence in survival, when you first catch sight of the illusion your SPL will grab the most obviously coherent interpretation from the PPL for you to scrutinise. Having studied it and found nothing of immediate interest, the PPL is once again called upon for the next interpretation, in case features that weren’t important in the last one turn out to be critical.
Thus, visual illusions could work by making two possible interpretations equally attractive to the SPL. In continually checking for new information, the SPL would toggle between the two interpretations within the PPL. Switching rates could reflect either how good a brain is at checking an image, or the level of detail to which that particular brain looks at images before moving on.
From Andrew Thomas
Griggs reports that the switching of perceptions in visual illusions is likely to be due either to the SPL region of the brain triggering a visual reset, or people with large SPLs being better at noticing other interpretations of the illusion.
Having looked at the allegorical picture Blossom and Decay that appeared with the article, I find that I am most likely to see a skull when looking at the upper part of the arch or the teeth, but when I look at the eye area I always see the two people under an arch. Interestingly, when I focus on the skull’s nose area I find myself simultaneously seeing both the people and the skull.
Have the team considered a third explanation: that the rate of eye movement causes the rate of this switching? This alternative possibility would seem to be given credence by the statement that the SPL is also known to control attention.
Birmingham, UK
Jessica Griggs writes:
鈥� The researchers considered the rate of eye movement. Rather than using a static image, like the one used to illustrate the article, participants were shown a rotating sphere of dots, and the illusion related to their perception of the direction of rotation. The researchers minimised the effects of eye movement by asking the participants to fix their gaze on a central red dot and blink at a natural rate. They also told the volunteers that a computer was controlling the switches in rotation direction, so that they would not try to control it themselves, for example, by blinking.
Philosophical sense
Bijal Trivedi reports that use of the vOICe device, which generates soundscapes for visually impaired people, has resulted in some rewiring in the users’ brains so that some can now use sound to create qualitative pictures of their environment 鈥� effectively seeing with their ears (14 August, p 42)
These observations are significant from a philosophical perspective. One of the cornerstones of philosophical inquiry, which hinges on the distinction between perception and reality, is the idea that the senses are distinct. Even should one be able to perceive reality, this distinction means it is impossible to communicate our perceptions accurately.
The Greek philosopher Gorgias, wrote that: “speech can never exactly represent perciptibles, since it is different from them, and perceptibles are apprehended each by the one kind of organ, speech by another. Hence, since the objects of sight cannot be presented to any other organ but sight, and the different sense-organs cannot give their information to one another, similarly speech cannot give any information about perceptibles. Therefore, if anything exists and is comprehended, it is incommunicable.”
This barrier between the senses has now been breached, and so we should reconsider this cornerstone of philosophy and the nature of information itself.
Acoustic decoration
Trevor Cox reports on findings that, contrary to the lengthy ponderances of Roman engineer Vitruvius, there are no perceptible acoustic benefits to decking out rooms with bronze vases (21 August, p 44).
It is an incidental property of many vessels that they resonate more musically when struck, rubbed or blown into. The acoustician-baffling vases that have been discovered in ancient theatres, churches and mosques probably held flowers.
From Steve Whitehouse
I was in an audio store the other day, and I told the staff I was building a replica of a church built some time between the 11th and 16th centuries.
“We have just the thing,” they said: gold-plated, mono-crystalline, oxygen-free vases handcrafted by Cistercian monks. They assured me these would make a huge difference to the acoustics, enhancing vocal clarity and adding subtle tones to the music to make it richer and fuller. After all, they said, if it was good enough for the Greeks and Romans then surely it is good enough for me.
It seems there is nothing new in selling audio products.
Auckland, New Zealand
Wood for the trees
Don Patterson argues that the carbon cost of nuclear energy 鈥� or any new technology 鈥� prevents it from being as compelling a solution to the energy crisis as its proponents claim (21 August, p 26). If the green movement had been around in about 1700, they would probably have argued that the sacrifice of trees for charcoal burning was a disgrace, and that the nation would be treeless within a lifetime. And although this newfangled coal mining might alleviate the trees’ plight, those people would probably have argued that the demands placed by coal mining on charcoal 鈥� to forge the necessary iron and steel 鈥� would be so great as to mean the end of English forests.
I leave it to your readers to follow this argument to its conclusion.
Hormones not drugs
Catherine de Lange writes about the medicalisation of recreational drugs (4 September, p 8). There is a history of such drugs being dished out to patients: ritalin is an amphetamine, and methamphetamine (crystal meth) was routinely used as a treatment in the 1960s. LSD was given to people who were diagnosed with depression and schizophrenia in the UK in the 1950s and 60s. Some of these patients developed chronic symptoms, which they blamed on taking the drug ().
Given the mind-altering properties of many recreational drugs, I think it would be safer to treat people with the hormone dehydroepiandosterone, or DHEA, which could be of benefit to those with raised cortisol levels, as is the case in combat stress (19 May 2009, p 40).
Unresolved problem
Help, we appear to be trapped! I and my myriad doppelgangers were reading Rachel Courtland’s article on how the concept of multiple universes causes a problem for the idea of infinite superpositions in the standard model of quantum mechanics, when we came across the instruction “see Identity crisis” (28 August, p 6). This was a reference to a sidebar.
About half of us obeyed, and then came across the instruction “see main story”. Again, about half of us obeyed and, not knowing where to start, began reading the main article from the beginning. On again encountering the instruction “see Identity crisis” we are now in a simultaneous superposition of an indefinite number of states, some of us probably stuck in an infinite loop.
Alas, we are reading this alone and there is no one to observe us and make us real. However, all is not lost; I am writing to you and if you read it, it may count as an observation. But, just in case, please publish this in your Letters section where the vast number of readers is bound to make us real again.
For the record
鈥� An improbable spelling error occurred in our article on improbable ideas. Apologies to Lesley Robertson (not Robinson), curator of the Delft School of Microbiology archives, the Netherlands, (11 September, p 38).