Course Hero - We put you ahead of the curve!

You have requested the below document.

Coursehero >> Pennsylvania >> Drexel >> VISCOG 01

News 6 & Comment TRENDS in Cognitive Sciences Vol.5 No.1 January 2001 In Brief Rumelhart Prize to be announced at Cognitive Science Society The David E. Rumelhart Prize will be awarded for the first time in 2001.The award is for recent, significant contributions to the formal analysis of human cognition and will go either to an individual or to a team.The scope of research eligible for the award includes mathematical modelling of human cognitive processes, formal analysis of language and other products of human cognitive activity, and computational analyses of human cognition.The prize, which includes a monetary award of $100,000, will be funded by the Robert J. Glushko and Pamela Samuelson Foundation in San Francisco. The first winner will be announced at the meeting of the Cognitive Science Society in Edinburgh this summer (COGSCI 2001, 1 4 August).The recipient will deliver the Prize Lecture at the subsequent meeting, at George Mason University, in 2002. James L. McClelland chairs the selection panel and full details are available at http://www.cnbc.cmu.edu/derprize/.This site also provides information on David Rumelhart himself and his belief that cognitive science should have formal theories, such as those in linguistics, as well as mathematical and computational models. Cognitive neuroscientists win Grawemeyer psychology prize Michael Posner (Director of the Sackler Institute for Developmental Psychobiology, NewYork), Marcus Raichle and Steven Peterson (both at Washington University, St Louis) have won the Grawemeyer psychology prize for their work in the 1980s on measuring mental functions of the brain. The prize rewards their pioneering brain imaging work that led to the discovery of neuro-anatomical networks for language and attention.The prize, worth $200,000, received 150 nominations and is funded by the Grawemeyer Foundation. Further details of the award are available at www.grawemeyer.org/news-updates. Where the brain gets ready for action The more the dorsolateral prefrontal cortex (dlPFC) activates, the better the person performs the subsequent task.This area on the outer surface of the frontal lobes appears to signal the level of preparedness, or how well the brain anticipates a particular action. That is the conclusion of Cameron Carter, who leads a group of researchers at University of Pittsburgh School of Medicine. He says the dlPFC seems to look forward to what the brain needs to do next in order to perform a given task .The researchers presented their results at the 30th Annual Meeting of the Society for Neuroscience.Their studies involved fMRI imaging during the Stroop test, in which subjects are shown words for colours and are asked either to read the word out loud, or to name the colour of the ink the word is written in. When the subjects knew they would have to name the colour of the ink the more difficult task the dlPFC activation was very high. A second study involved prior knowledge of task-switching. When subjects were warned they would have to switch tasks, the dlPFC activated, whereas when they were not warned, it remained inactive. Cameron Carter concludes that although many regions of the brain take part in executive functions, the dlPFC seems to be uniquely involv ed in preparing attention for what is just about to happen and is more active when a person has to prepare to overcome a habitual response or switch from one task to another. Letters An egocentric account of the visual guidance of locomotion The recent series of articles (Lappe et al.1; Wann and Land2) and replies (Harris and Rogers3; Lappe et al.4; Fajen and Warren5) has been useful in drawing out what is and isn t known about the roles of optic flow and perceived egocentric direction in the visual guidance of locomotion. The proposal that perceived egocentric direction has a central role in the guidance of locomotion6 appears to be no longer disputed. Here we wish to clarify some implications of the strong version of this proposal, that locomotion relies exclusively on perceived egocentric direction. How does an observer perceive the egocentric direction of an object? The direction relative to the trunk is minimally given by the orientation of the head on the trunk, the orientation of the eye in the head and the retinal location of the target (note that, lest there be any confusion, current direction of locomotion is not required). There are other influences on perception of egocentric direction, including the structure within the optic array, or retinal image7,8. Furthermore, and of special interest, changes within the optic array ( optic flow ) can also influence perception of direction. Natural optic flow experienced when walking has been shown to change perceived egocentric direction9. Artificially generated translational flow has also been shown to have a fast-acting influence on perceived direction10,11. A simple interpretation of these effects is that, in the former case, optic flow recalibrates perceived egocentric direction, whereas in the latter, flow provides gaze-movement information that is used in the perception of egocentric direction. What are the consequences of the influences described above? If walking observers do guide themselves using perceived egocentric direction, then it follows that both the structure of the visual environment and the change in structure ( optic flow ) would be predicted to have an influence on locomotion. Are there data in the two published experimental papers6, 12 that are compatible with either of these predictions? The differences in trajectory reported with different prisms6,12 and environments12 fit the structure prediction. Unfortunately, Fajen and Warren s assertion notwithstanding, it is difficult to interpret any published data in support of a fast-acting influence of optic flow. We should not take this as firm evidence against such an influence of flow, but rather as an indication that further experiment or more detailed data analysis is still required. Should subsequent papers demonstrate a fast-acting influence of flow, then parallel measurement of biases in perception of egocentric direction and locomotor trajectory would help determine whether the use of flow is direct (flow-based strategies are used) or indirect (flow influences perception of direction). http://tics.trends.com 1364-6613/01/$ see front matter 2001 Elsevier Science Ltd. All rights reserved. News & Comment TRENDS in Cognitive Sciences Vol.5 No.1 January 2001 7 Turning to Wann and Land s article2, they outlined a variety of strategies that could be used to guide an observer along a curved path (Fajen and Warren s letter describes an unrelated task of steering towards a static virtual target). We note that to steer a vehicle around a bend it is not necessary to determine anything as complex as bend curvature: if the car is already in the lane it can be steered by simply keeping constant the direction of the tangent point, or the direction of a piece of the (inner or outer) road edge at a fixed distance ahead. A model of steering recently has been developed in our laboratory13 that is based on keeping constant the direction of two points: a far point in the distance (e.g. the vanishing point or tangent point), and a near point in the centre of the lane. This model drives in a naturalistic motorway/highway simulation with full vehicle dynamics and generates predictions of both steering and eye-movement behaviour. Validated with human-driver data from our fixed-base driving simulator, the model accounts for various aspects of driver perception and control during lane keeping, curve negotiation, and lane changing. Thus, egocentric direction suffices to produce realistic, human-like steering behaviour. Strong models have the benefit of being simple, and easy to test. By drawing on the broader literature on the perception of egocentric direction, it is possible to generate a large number of predictions about walking trajectories in differing visual environments. Although it may ultimately be found wanting, the strong egocentric direction model is currently the most parsimonious account of the published empirical data. Simon K. Rushton and Dario D. Salvucci Cambridge Basic Research, NissanTechnical Center North America, Inc., Four Cambridge Center, Cambridge, MA 02142, USA. e-mail: simon@cbr.com References 1 Lappe M. et al. (1999) Perception of self motion from visual flow. Trends Cognit. Sci. 3, 329 336 2 Wann, J.P. and Land M. (2000) Steering with or without the flow: is the retrieval of heading necessary? Trends Cognit. Sci. 4, 319 324 3 Harris, J.M. and Rogers, B.J. (1999) Going against the flow. Trends Cognit. Sci. 3, 449 450 4 Lappe et al.(1999) Reply to Harris and Rogers. Trends Cognit. Sci. 3, 450 5 Fajen, B.R. and Warren, W.H. (2000) Go with the flow. Trends Cognit. Sci. 4, 369 370 6 Rushton, S.K. et al. (1998) Guidance of locomotion on foot uses perceived target location rather than optic flow. Curr. Biol. 8, 1191 1194 7 Rock, I. et al. (1966) Immediate correction and adaptation based on viewing a prismatically displaced scene. Percept. Psychophys. 1, 351 354 8 Bridgeman, B. and Graziano, J.A. (1989) Effect of context and efference copy on visual straight ahead. Vis. Res. 29, 1729 1736 9 Held, R. and Bossom, J. (1961) Neonatal deprivation and adult rearrangement: complementary techniques for analyzing plastic sensory motor coordinations. J. Comp. Physiol. Psychol. 54, 33 37 10 Brecher, G.A. et al. (1972) Relation of optical and labyrinthean orientation. Optica Acta 19, 467 471 11 Post, R.B. and Heckman, T. (1986) Induced motion and apparent straight-ahead during prolonged stimulation. Percept. Psychophys. 40, 263 270 12 Wood R.M. et al. (2000) Weighting to go with the flow. Curr. Biol. 10, 545 546 13 Salvucci, D.D. et al. Toward an integrated model of driver behavior in a cognitive architecture. Transportation Res. Rec. (in press) PII: S1364-6613(00)01562-X The future of flow? A recent Perspective article1 outlined a general theory for the control of steering around a bend, which was novel in that it did not require heading information to be obtained from optic flow. It addressed an issue that is currently hotly debated in the literature, namely the extent to which flow and direction are used for locomotion. To summarize a 50-year history of interest in the field, since Gibson s seminal work2 it has been thought that heading information obtained from the optic flow field is used to judge the direction of one s locomotion. Gibson s theories have been backed up by many years of experimental and theoretical work (for details, see a recent review by Lappe et al.3). In 1998, Rushton et al. published data suggesting that despite optic flow being a sufficient cue for heading, visual direction is more important in the natural environment4 (Llewellyn made a related suggested earlier5). They showed that when observers wear displacing prisms during walking, they follow curved trajectories, as would be expected if direction, but not flow, is used. Until very recently (see Ref. 6) this work has represented the only full publication of empirical data on this issue. The possible role of direction as an alternative to flow is therefore still new, and Wann and Land add to the debate by presenting a more general theory for the use of direction. In the October 2000 issue of TICS, Fajen andWarren responded to that Perspective, with a letter suggesting that there is now empirical evidence that optic flow plays a significant role in the control of heading7. They said that the evidence is now available to rule heading from flow back in and rule out direction as the only cue. This would seem to be rather premature. Many of the studies cited are in abstract form and without experimental detail cannot be argued for or against. One has been published in more detail6 and it is that which I wish to comment on here. Wood et al. repeated the prism experiments of Rushton et al. using three conditions, one with a very narrow field of view, one intermediate and one with a full field of view plus other visual information, which included a regular square grid laid out on the ground. It was found that the more visual information that was available, the less paths were curved. In their letter, Fajen and Warren interpret this result as being due to the use of flow. However, Wood et al. themselves made the point that the rich-cue condition also contained markings that provided a static reference. Cues other than visual direction may help to reduce the influence of the prisms, but they are not necessarily optic flow cues. I agree with Fajen and Warren when they say that testing the role of optic flow in locomotion is an empirical matter . But have reports of its demise been greatly exaggerated ? After 50 years of the dominance of flow in locomotion, and of agreement in the field that it was the most important variable, it remains startling and interesting that visual direction is offered as an alternative. If nothing else, the issue has changed from that of asking questions about how flow is used, to asking questions about how flow and direction might both contribute, and which is dominant. This is an empirical issue and one which may not have been adequately addressed. I look forward to seeing other studies published in a form whereby we can discuss and criticise them in detail. Julie M. Harris Department of Psychology, University of Newcastle uponTyne, UK NE1 7RU e-mail: j.harris@ncl.ac.uk References 1 Wann, J. and Land, M. (2000) Steering with or without the flow: is the retrieval of heading necessary? Trends Cognit. Sci. 4, 319 324 2 Gibson, J.J. (1958) Visually controlled locomotion and visual orientation in animals. Br. J. Psychol. 49, 182 194 3 Lappe, M. et al. (1999) Perception of self-motion from visual flow. Trends Cognit. Sci. 3, 329 336 4 Rushton, S.K. et al. (1998) Guidance of locomotion on foot uses perceived target location rather than optic flow. Curr. Biol. 8, 1191 1194 http://tics.trends.com 1364-6613/01/$ see front matter 2001 Elsevier Science Ltd. All rights reserved.

Find millions of documents here - Study Guides, Homework Solutions, Papers, Exam Answer Keys and more. Course Hero has millions of course related materials that will enable you to learn better, faster and get an A in all your courses.
Below is a small sample set of documents:

TRB01.pdf
Path: Drexel >> VISCOG >> 01 Fall, 2008

HCI01.pdf
Path: Drexel >> HCI >> 01 Fall, 2008
CSR01.pdf
Path: Drexel >> VISCOG >> 01 Fall, 2008
CS01.pdf
Path: Drexel >> CS >> 01 Fall, 2008
VIV01.pdf
Path: Drexel >> VISCOG >> 01 Fall, 2008
ICCM01.pdf
Path: Drexel >> VISCOG >> 01 Fall, 2008
CHI01.pdf
Path: Drexel >> CHI >> 01 Fall, 2008
ETRA00.pdf
Path: Drexel >> VISCOG >> 00 Fall, 2008
ETRA00b.pdf
Path: Drexel >> VISCOG >> 00 Fall, 2008
CHI00.pdf
Path: Drexel >> CHI >> 00 Fall, 2008
graph02.pdf
Path: Drexel >> VISCOG >> 02 Fall, 2008
CHI99.pdf
Path: Drexel >> CHI >> 99 Fall, 2008
CSC98.pdf
Path: Drexel >> CSC >> 98 Fall, 2008
CHI98.pdf
Path: Drexel >> CHI >> 98 Fall, 2008
JMSY4.pdf
Path: Drexel >> LAYTON >> 4 Fall, 2008
StructDamageB4C.pdf
Path: Drexel >> NANO >> 4 Fall, 2008
cm4_2_005.pdf
Path: Drexel >> CM >> 4 Fall, 2008
SemicondSciTech01.pdf
Path: Drexel >> NANO >> 01 Fall, 2008
MRS2000_Q98.pdf
Path: Drexel >> NANO >> 2000 Fall, 2008
ApplPhysLett00.pdf
Path: Drexel >> NANO >> 00 Fall, 2008
JMaterRes00.pdf
Path: Drexel >> NANO >> 00 Fall, 2008
Nature99.pdf
Path: Drexel >> NANO >> 99 Fall, 2008
SemicondSciTech99.pdf
Path: Drexel >> NANO >> 99 Fall, 2008
RevSciInstrum99.pdf
Path: Drexel >> NANO >> 99 Fall, 2008
JApplPhys98.pdf
Path: Drexel >> NANO >> 98 Fall, 2008
phtrmicroramanmatres97.pdf
Path: Drexel >> NANO >> 97 Fall, 2008
JApplPhys97.pdf
Path: Drexel >> NANO >> 97 Fall, 2008
JAP2003.pdf
Path: Drexel >> JAP >> 2003 Fall, 2008
Nature01.pdf
Path: Drexel >> NANO >> 01 Fall, 2008
WettingLangmuir2006.pdf
Path: Drexel >> NANO >> 2006 Fall, 2008
FluidEngg2006.pdf
Path: Drexel >> NANO >> 2006 Fall, 2008
sundarbabumicrofl2005.pdf
Path: Drexel >> NANO >> 2005 Fall, 2008
NanoLettersMagnetic2005.pdf
Path: Drexel >> NANO >> 2005 Fall, 2008
CPLNanotubes2005.pdf
Path: Drexel >> NANO >> 2005 Fall, 2008
APL2004.pdf
Path: Drexel >> APL >> 2004 Fall, 2008
NanoLetters2004.pdf
Path: Drexel >> NANO >> 2004 Fall, 2008
Ye2004-APL.pdf
Path: Drexel >> NANO >> 2004 Fall, 2008
Over08_NIRT_Drexel.pdf
Path: Drexel >> NANO >> 08 Fall, 2008
SvetlanaCarbon2002.pdf
Path: Drexel >> NANO >> 2002 Fall, 2008
MRI2002.pdf
Path: Drexel >> NANO >> 2002 Fall, 2008
ApplPhysLett01.pdf
Path: Drexel >> NANO >> 01 Fall, 2008
Carbon01.pdf
Path: Drexel >> NANO >> 01 Fall, 2008
MRS2000_A74.pdf
Path: Drexel >> NANO >> 2000 Fall, 2008
CrystalGrowthDesign01.pdf
Path: Drexel >> NANO >> 01 Fall, 2008
JMR2000.pdf
Path: Drexel >> NANO >> 2000 Fall, 2008
Science00.pdf
Path: Drexel >> SCIENCE >> 00 Fall, 2008
GogotsiNickelCarbon1998.pdf
Path: Drexel >> NANO >> 1998 Fall, 2008
JACerS2003.pdf
Path: Drexel >> NANO >> 2003 Fall, 2008
J8.pdf
Path: Drexel >> J >> 8 Fall, 2008
J9.pdf
Path: Drexel >> J >> 9 Fall, 2008
J10.pdf
Path: Drexel >> J >> 10 Fall, 2008
J14.pdf
Path: Drexel >> J >> 14 Fall, 2008
J15.pdf
Path: Drexel >> J >> 15 Fall, 2008
Design.pdf
Path: Drexel >> CS >> 36 Fall, 2008
Requirements.pdf
Path: Drexel >> CS >> 36 Fall, 2008
Integration_Test_Plan.pdf
Path: Drexel >> CS >> 36 Fall, 2008
Acceptance_Test_Plan.pdf
Path: Drexel >> CS >> 36 Fall, 2008
dsp2009.pdf
Path: Drexel >> ECE >> 2009 Fall, 2008
imece2008-66436.pdf
Path: Drexel >> ECE >> 2008 Fall, 2008
EMBC08_0549_FI.pdf
Path: Drexel >> ECE >> 08 Fall, 2008
gensips08.pdf
Path: Drexel >> ECE >> 08 Fall, 2008
safe2007.pdf
Path: Drexel >> ECE >> 2007 Fall, 2008
AAAI2007.pdf
Path: Drexel >> CS >> 2007 Fall, 2008
AAAI2007.pdf
Path: Drexel >> CS >> 53 Fall, 2008
aamas07.pdf
Path: Drexel >> CS >> 07 Fall, 2008
aamas07.pdf
Path: Drexel >> CS >> 2007 Fall, 2008
aamas07.pdf
Path: Drexel >> CS >> 53 Fall, 2008
class1.ppt.pdf
Path: Drexel >> ECE >> 1 Fall, 2008
September22_2005_minutes.pdf
Path: Drexel >> ECE >> 22 Fall, 2008
PR08.pdf
Path: Drexel >> CS >> 08 Fall, 2008