Thank you to the organisers of the 13th European Conference on Eye Movements, Bern, Switzerland, 14th-18th August 2005, and to everyone who came along to see our new High Speed Video Eyetracker Toolbox and made its launch such a success.

Go to High Speed Video Eyetracker Toolbox product pages

 

We are delighted to announce that the winner of the ECEM Poster Prize, sponsored by Cambridge Research Systems, was Rebecca L Johnson for her interesting poster, Top-down and bottom-up effects in pure alexia.

Here is Rebecca at ECEM with Prof. Rudolf Groner (left picture) and with Steven Elliott, Sales and Technical Support Manager of Cambridge Research Systems (right picture).

Top-down and bottom-up effects in pure alexia

R. Johnson (University of Massachusetts Amherst, Department of Psychology, Tobin Hall, 1003 Amherst, USA. becca@psych.umass.edu)
K. Rayner (University of Massachusetts)

Pure Alexia (letter-by-letter reading) is a type of acquired dyslexia in which premorbidly literate individuals have difficulty reading. The primary characteristic of LBL reading is a large increase in naming latency as a function of the number of letters in a word (the word length effect). LBL reading is assumed to be the result of damage to the mechanisms responsible for parallel processing of letters, thus leading to the serial encoding of the component letters in a word. In accord with this assumption, the eye-movement data from GJ (a pure alexic with left occipito-temporal brain damage and right homonymous hemianopia) demonstrates a pattern strikingly similar to normal readers given a one-letter moving window. GJ also exhibits a word-length effect in reading sentences and a sensitivity to word frequency and predictability. These data support an interactive account of reading in pure alexics in which the degraded bottom-up input relies strongly on intact top-down influences.

Go to the official ECEM 13 web photo gallery

 

Another interesting poster, A contingent CRT display for saccadic adaptive control experiments, was given by William Payne, Chris Harris & Peter West, SensoriMotor Laboratory, University of Plymouth, UK & Cambridge Research Systems, UK.

Understanding saccade adaptive control requires an intra-saccadic stimulus change to be performed during the ongoing saccade. Unfortunately, the limited availability of saccade contingent displays has limited research in this area. An obvious choice for a stimulus presentation system is a computer controlled CRT display. However, this potentially suffers from artifacts caused by frame-period quantization.

We explore a method for saccade contingent display on a CRT is described which has been developed and tested using Scalar IRIS infra-red limbus tracker and a Cambridge Research Systems Visage Visual Stimulus Generator.

A prosaccade task was used to illicit the eye movements which controlled a 167 Hz CRT display. A video frame-synchronized digital signal processing system was used to sample, filter and differentiate the eye movement data, which was then evaluated against a simple velocity threshold. Upon saccade detection, the stimulus display was modified according to the experimental protocol.

Preliminary data indicates a variable frame update delay of 15-25 ms. Thus, this novel technique allows an arbitrary change in the visual display during saccades of modest amplitudes. This study suggests that it will be possible to investigate saccade adaptive control using readily available technology, and to have unprecedented flexibility in the control of the contingent image properties.

Go to Research Topics Saccadic Adaptation pages

The full poster and information about William Payne's work on saccadic adaptation are available in our Research Topics pages.

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