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Author

Patrick Langdon

Other affiliations: Honeywell, University of Sheffield
Bio: Patrick Langdon is an academic researcher from University of Cambridge. The author has contributed to research in topics: Population & Universal design. The author has an hindex of 31, co-authored 283 publications receiving 3454 citations. Previous affiliations of Patrick Langdon include Honeywell & University of Sheffield.


Papers
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Journal ArticleDOI
TL;DR: The architecture of the model may offer a functional explanation of hitherto mysterious tectocerebellar projections, and a framework for investigating in greater detail how the cerebellum adaptively controls saccadic accuracy.
Abstract: Saccadic accuracy requires that the control signal sent to the motor neurons must be the right size to bring the fovea to the target, whatever the initial position of the eyes (and corresponding state of the eye muscles). Clinical and experimental evidence indicates that the basic machinery for generating saccadic eye movements, located in the brainstem, is not accurate: learning to make accurate saccades requires cerebellar circuitry located in the posterior vermis and fastigial nucleus. How do these two circuits interact to achieve adaptive control of saccades? A model of this interaction is described, based on Kawato's principle of feedback-error-learning. Its three components were (1) a simple controller with no knowledge of initial eye position, corresponding to the superior colliculus; (2) Robinson's internal feedback model of the saccadic burst generator, corresponding to preoculomotor areas in the brain-stem; and (3) Albus's Cerebellar Model Arithmetic Computer (CMK), a neural net model of the cerebellum. The connections between these components were (I) the simple feedback controller passed a (usually inaccurate) command to the pulse generator, and (2) a copy of this command to the CMAC; (3) the CMAC combined the copy with information about initial eye position to (4) alter the gain on the pulse generator's internal feedback loop, thereby adjusting the size of burst sent to the motor neurons. (5) If the saccade were inaccurate, an error signal from the feedback controller adjusted the weights in the CMAC. It was proposed that connection (2) corresponds to the mossy fiber projection from superior colliculus to oculomotor vermis via the nucleus reticularis tegmenti pontis, and connection (5) to the climbing fiber projection from superior colliculus to the oculomotor vermis via the inferior olive. Plausible initialization values were chosen so that the system produced hypometric saccades (as do human infants) at the start of learning, and position-dependent hypermetric saccades when the cerebellum was removed. Simulations for horizontal eye movements showed that accurate saccades from any starting position could be learned rapidly, even if the error signal conveyed only whether the initial saccade were too large or too small. In subsequent tests the model adapted realistically both to simulated weakening of the eye muscles, and to intrasaccadic displacement of the target, thereby mimicking saccadic plasticity in adults. The architecture of the model may therefore offer a functional explanation of hitherto mysterious tectocerebellar projections, and a framework for investigating in greater detail how the cerebellum adaptively controls saccadic accuracy.

137 citations

Journal ArticleDOI
TL;DR: This paper addresses the sensory, cognitive and motor dimensions of user capability that are important for product interaction by setting out the relationship between user capability and product demand.
Abstract: Designers require knowledge and data about users to effectively evaluate product accessibility during the early stages of design. This paper addresses this problem by setting out the sensory, cognitive and motor dimensions of user capability that are important for product interaction. The relationship between user capability and product demand is used as the underlying conceptual model for product design evaluations and for estimating the number of people potentially excluded from using a given product.

111 citations

Journal ArticleDOI
TL;DR: The principal finding was that similarity of prior experience to the usage situation was the main determinant of performance, although there was also some evidence for a gradual, age-related capability decline.
Abstract: Many products today are laden with a host of features which, for the majority of users, remain unused and often obscure the use of the simple features of use for which the product was devised (Norman in The design of everyday things. Basic Books, 2002; Keates and Clarkson in Countering design exclusion—an introduction to inclusive design. Springer, 2004). Since the cognitive capabilities of the marketed target group are largely not affected by age-related impairment, the intellectual demands of such products are frequently high (Rabbitt in Quart J Exp Psychol 46A(3):385–434, 1993). In addition, the age and technology generation of a product user will colour their expectations of the product interface and affect the range of skills they have available (Docampo in Technology generations handling complex User Interfaces. Ph. D. thesis, 2001). This paper addresses the issue of what features of products make them easy or difficult to learn to use, for the wider population as well as the older user, and whether and in what way individual prior experience affect the learning and use of a product design. To achieve the above, the interactions of users of varying ages and capabilities with two different everyday products were recorded in detail as they performed set tasks. Retrospective verbal protocols were then analysed using a category scheme based on an analysis of types of learning and cognition errors. This data was then compared with users’ performance on individual detailed experience questionnaires and a number of tests of general and specific cognitive capabilities. The principal finding was that similarity of prior experience to the usage situation was the main determinant of performance, although there was also some evidence for a gradual, age-related capability decline. Users of all ages adopted a means-end or trial and error interaction when faced with unfamiliar elements of the interaction. There was a strong technology generation effect such that older users were reluctant or unable to complete the required tasks for a digital camera.

110 citations

Journal ArticleDOI
TL;DR: The theory of primary metaphor is proposed and its validity as a source of design guidance for gesture interaction with abstract content on mobile multitouch devices is explored.

91 citations

Proceedings ArticleDOI
08 Jul 2002
TL;DR: This paper discusses work that aims to reveal the nature of people with motion-impairments' difficulties through analyses that consider the cursor's path of movement, and introduces new cursor characteristics for motion-impaired users.
Abstract: "Point and click" interactions remain one of the key features of graphical user interfaces (GUIs). People with motion-impairments, however, can often have difficulty with accurate control of standard pointing devices. This paper discusses work that aims to reveal the nature of these difficulties through analyses that consider the cursor's path of movement. A range of potential cursor measures was applied, and a number of them were found to be significant in capturing the differences between able-bodied users and motion-impaired users, as well as the differences between a haptic force feedback condition and a control condition. cursor measures found in the literature, however, do not make up a comprehensive list, but provide a starting point for analysing cursor movements more completely. Six new cursor characteristics for motion-impaired users are introduced to capture aspects of cursor movement different from those already proposed.

91 citations


Cited by
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Journal ArticleDOI
TL;DR: Reading a book as this basics of qualitative research grounded theory procedures and techniques and other references can enrich your life quality.

13,415 citations

Book
01 Dec 1996
TL;DR: Clark as mentioned in this paper argues that the mental has been treated as a realm that is distinct from the body and the world, and argues that a key to understanding brains is to see them as controllers of embodied activity.
Abstract: From the Publisher: The old opposition of matter versus mind stubbornly persists in the way we study mind and brain. In treating cognition as problem solving, Andy Clark suggests, we may often abstract too far from the very body and world in which our brains evolved to guide us. Whereas the mental has been treated as a realm that is distinct from the body and the world, Clark forcefully attests that a key to understanding brains is to see them as controllers of embodied activity. From this paradigm shift he advances the construction of a cognitive science of the embodied mind.

3,745 citations

Journal ArticleDOI
TL;DR: A survey of factor analytic studies of human cognitive abilities can be found in this paper, with a focus on the role of factor analysis in human cognitive ability evaluation and cognition. But this survey is limited.
Abstract: (1998). Human cognitive abilities: A survey of factor analytic studies. Gifted and Talented International: Vol. 13, No. 2, pp. 97-98.

2,388 citations

01 Jan 2016
TL;DR: Biomechanics and motor control of human movement is downloaded so that people can enjoy a good book with a cup of tea in the afternoon instead of juggling with some malicious virus inside their laptop.
Abstract: Thank you very much for downloading biomechanics and motor control of human movement. Maybe you have knowledge that, people have search hundreds times for their favorite books like this biomechanics and motor control of human movement, but end up in infectious downloads. Rather than enjoying a good book with a cup of tea in the afternoon, instead they juggled with some malicious virus inside their laptop.

1,689 citations

01 Jun 1986

1,197 citations