October 29, 2012
RedOrbit Exclusive Interview: Dr. Matthew Longo, Birkbeck University Of London
Jedidiah Becker for redOrbit.com — Your Universe Online
When it comes to providing an objective account of the world around us, the human brain can be a notoriously inaccurate and biased reporter. Scholarly literature in the fields of psychology and neuroscience are full of studies that demonstrate how the brain 'fudges' the picture of reality with which it presents our conscious mind, often favoring a useful or convenient interpretation of our surroundings over a strictly accurate one. And as a number of studies have shown in recent years, our perception of our environment is never more distorted than when we find ourselves in emotionally intense situations.
Read the original article “How Spatial Perception Is Influenced By Fear” first.
RO: Professor Longo, what attracted you and your colleague Dr. Lourenco to this research topic — the ability of fear to affect our spatial perception?
Longo: Stella Lourenco and I started collaborating when we were both doctoral students at the University of Chicago, using some seed funding from our department to start a project investigating how we perceive the 'near space' immediately surrounding the body differently from the space farther away. After we both graduated, we continued this research, first in Stella's lab at Emory University, and now as well in my lab at Birkbeck.
Initially, we focused on the role of near space in guiding action. Our early results showed that altering people's ability to act produced flexible alterations of how much space around the body the brain codes as 'near.' For example, we showed that using a tool expands the size of near space, while putting heavy weights on the arms causes it to contract. More recently, we've became interested in the idea that near space might be involved in a quite different function, namely protecting the body against potentially threatening objects. Specifically, we speculated that near space might be involved in feelings of claustrophobia in constrained spaces. We reasoned that if stimuli in near space were coded as potentially threatening, that people with a larger near space would feel more anxious in any given enclosed environment since more things would impinge on their near space. Indeed, we found that people with a larger near space around their body, measured using the methods we developed in our earlier research, reported more claustrophobic fear on a standard questionnaire than people with a smaller near space.
Our recent study emerged from that research. We were interested in how stimuli which many people find intrinsically threatening — like snakes or spiders — alter our perception. We used a phenomenon called 'looming' in which objects on a direct collision course with an observer produce a specific pattern of expansion on the retina. Traditionally, looming has been considered a purely optical cue specifying the time until objects will collide with an observer. In contrast to that view, we showed that people underestimate the time-to-collision of threatening stimuli (snakes and spiders) compared to less threatening stimuli (butterflies and rabbits). Further, this bias is larger in people who report more fear of snakes and spiders.
RO: Your colleague Professor Lourenco mentioned that our tendency to underestimate collision time when faced with a potentially threatening object probably had some clear survival advantages for our early ancestors. As anyone even casually interested in science knows, evolution and natural selection have been some of the most powerful tools in the advancement of the biological sciences in the last hundred years — from genetics, biochemistry and cell biology to ecology and physiology. However, we don't typically hear as much about the role of evolutionary theory in the field of psychology. In your estimation, how important is evolution in the study of modern psychology?
Longo: Discussion of evolution is perhaps less conspicuous in many areas of psychology than in other areas of the biological sciences, but forms the essential background against which almost all research in psychology is conducted. One of the central questions of psychology over the past century has been what changes in the evolution of human cognition led to the tremendous complexity and sophistication of human social organization, which appeared unprecedented elsewhere in the animal kingdom. This remains a major topic of research, with proposed answers including such things as language, the opposable thumb, and (more recently) 'theory of mind.' The past two decades have seen increasing prominence of more explicit discussion of evolutionary issues in psychology, notably in the fields of comparative psychology and what´s become known as evolutionary psychology.
The study of looming visual stimuli is a good example of the importance of evolutionary considerations in shaping psychological research. Research on looming emerged from the tradition of 'ecological optics' developed by Professor James Gibson of Cornell University in the 1960s. Gibson argued forcefully that perception could only be understood by considering how animals actually use their senses in their actual environments. Thus, rather than present his participants with abstract shapes or other meaningless stimuli, Gibson gave detailed consideration to what cues in complex sensory environments provided information about aspects of the world critical for an organism´s survival.
Gibson's work on looming was motivated by his analysis of the optics of objects on a collision course with an observer. He and his colleagues showed that monkeys made repeated defensive responses when shown a shadow on a projection screen which increased in size in a specific pattern mimicking what happens to light projected on the eyes when an object moves directly towards us. Subsequent research showed similar responses in human infants and even in human adults whose attention was distracted.
In parallel, research in neurophysiology documented nerve cells in the eyes of species such as mice and wasps which appear specialized for detecting looming visual stimuli. Thus, converging evidence from studies of animal behavior and from physiology suggested that the nervous systems of a wide range of animals have been shaped by evolution to rapidly detect and respond to rapidly approaching stimuli. Our recent findings are consistent with this interpretation, but show further that perception of looming stimuli is also modulated by our emotional reactions to the specific type of stimulus which is approaching.
RO: The study mentions that we don't yet understand exactly how fear is affecting our spatial perception. You explained that it may be causing the brain to perceive an approaching danger as moving faster than it actually is, or that it may simply be causing the individual to experience an enlargement of their personal sphere — their 'safety zone,' if you will. Have you got any professional 'hunches' about which of these two mechanisms it might be, and what would an experiment to test this look like?
Longo: I suspect that both types of explanation may be true to some extent. For example, there is evidence that stressful situations can cause time to seem to slow down, which could lead to underestimation of when an object would collide with us. On the other hand, there is also evidence from neurophysiological studies suggesting that rapidly approaching objects can expand the size of the 'near space' immediately surrounding the body. There are well established methods in the literature for measuring both the speed of the mental 'clock' and the extent of near space. We are currently planning experiments using these methods to try to assess these two interpretations.
RO: You and Professor Lourenco mentioned that you see your research as having implications for how we understand clinical phobias. Could you elaborate a bit on this?
Longo: Our research, both on claustrophobic fear and on fear of snakes and spiders, has measured individual differences in fear using an unselected sample of the general population, rather than people with clinical-level phobias. Of course, these are things that almost all of us experience some level of anxiety about, though to different degrees. What our results show is that the person-to-person differences in how intensely we experience these fears relate to the magnitude of the perceptual distortions we measure: People who report more fear show larger perceptual effects. Our suspicion is that the perceptual biases we have described would be even larger in people with clinical phobias.
An important question about clinical phobias is whether they arise from the top-down as a result of mistaken beliefs or attitudes about the feared object, or from the bottom-up as a result of biases in low-level aspects of perception. By showing that person-to-person differences in fear relate systematically to differences in basic aspects of vision, our results provide some support for the 'bottom-up' perspective, suggesting that pathological fears might reflect differences in the basic organization of sensory processing. Of course, this interpretation remains speculative, but it could have important implications for understanding where phobias come from and how they might be effectively treated.
RO: In recent years, researchers like the neuroscientist David Eagleman have been drawing popular attention to just how much of our brain's activity is completely outside of our conscious control as well as to the fact that our brains often present us with an 'edited' picture of reality that is not always objective or entirely accurate. Your specialty field of research focuses on how the brain creates and maintains distorted “body representations.” Could you tell us a bit more about this as well as where this recent study fits into your broader research interests?
Longo: My research has focused on understanding how the brain constructs representations of what our body is like and how these representations shape how we perceive the world. There is no mystery why the brain has distorted representations of the body at some level. Consider touch: it is obvious that some parts of the body have exquisite tactile sensitivity (such as the fingertips and lips), while other parts have much poorer sensitivity (such as the back).
It has long been known that maps in the brain which process tactile information devote many more resources to highly sensitive than to less sensitive skin regions. Every introductory psychology textbook shows a picture of the little man whose body is in the proportions of tactile maps with enormous hands and lips, commonly known as the 'Penfield homunculus' (after the eminent Canadian neurosurgeon Wilder Penfield who described this map in his patients). So it's not surprising that there are distorted representations of the body underlying basic processing of touch, as it is clearly advantageous to have a few body parts with exquisite sensitivity rather than having homogenously mediocre sensitivity all over the body.
What has been surprising in my recent research is that these distortions appear to be preserved (though in reduced form) in higher-level representations of the body underlying more complex aspects of perception. For example, when we cover up a participant's hand and ask them to indicate where they perceive the tip and knuckle of each finger as being, they place the knuckles much too far apart, as if the hand were represented as much wider and fatter than it actually is. Similarly, people overestimate how far apart two points touching the skin are when they are oriented across the width of the hand, compared to when they are oriented along the length of the hand.
Our recent research on looming emerges from a longstanding collaboration with Stella Lourenco, who I mentioned earlier. The main focus of our research has been on understanding how the brain represents the space immediately surrounding the body differently from the space farther away. As I described previously, our initial research on this issue was centered on how the body shapes space perception, both by comparing people with longer and shorter arms or by manipulating the body's ability to act, such as with tool use or putting heavy weights on the arms. We have gradually become increasingly interested, though, in how emotion affects our perception of space, and vice versa, which was the focus of our present study on looming.
RO: Judging from your list of publications, you've been a very busy researcher. Do you already have your eyes on your next research project, and would you care to give us a sneak peek?
Longo: As I described before, our recent work on space perception has shown intimate links between space perception and emotions, such as fear. One of the things I'm most excited about is extending this line of research to understand the relationship between emotion and how we represent our body.
One of the key aspects of clinical conditions such as body dysmorphia and some eating disorders is the abnormal emotions and attitudes that patients have towards their own body. I suspect that the various distortions of body representations that I've described may have implications for understanding emotional attitudes about the body and the factors that might alter them. This line of research remains at an early stage, but I'm optimistic that it will provide important insights into the relation between emotion and body representation.
RO: Dr. Longo, thanks very much for taking the time have a chat with us. On behalf of the redOrbit team and our readership, we wish you the best of luck on your future research and look forward to reading about your next research project.
Matthew Longo is a Lecturer in the Department of Psychological Sciences at Birkbeck, University of London where he directs the Body Representation Laboratory. He received his B.A. in Cognitive Science from the University of California at Berkeley in 2000 before completing his PhD in Psychology at the University of Chicago in 2006. After his PhD he moved to London to conduct Postdoctoral Research at the Institute of Cognitive Neuroscience at University College London. He has been at Birkbeck since 2010.
His research investigates how the brain constructs representations of the body and how these affect how we perceive the world around us. By combining a range of methods from cognitive neuroscience and perceptual psychology, he has shown that the brain maintains a diverse set of models of the body which have pervasive influences on perceptual abilities including the perception of touch, proprioception, pain, and visual space perception. He is an author of more than 50 scientific papers. His research has been supported by awards from the National Science Foundation (NSF) and the Royal Society of London.