A picture-based analysis of the startle eye blink

Case Study "Psychology"

A feasibility study, conducted by the Institute for Psychobiology at Trier University in cooperation with Prof. P. Gemmar from the Trier University of Applied Sciences, demonstrates a new picture-based method to measure the startle eye blink. The new method relies on high-frequency recording with the SMI Hi-Speed eye tracking system.

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Challenge

The intensity of blinking may inform about accompanying attentional und emotional  processes. In psychophysiological research, eye blinks are usually quantified by surface Electromyogramm (EMG) of the orbicularis oculi muscle, which closes  the eyelid.

Although  the EMG-method has many advantages, it is hampered by the restriction that  it cannot differentiate between entire and incomplete eyelid closure. This information is particularly interesting, since the extend of eyelid closure is affected by antagonistically active muscles whose activity can only partly be measured with EMG. 

Solution

The goal was to study a new method of picture-based analysis of startle eye blinks  and to compare the findings with EMG results. 

Conclusion

The data showed significant correlations between EMG and the picture-based assessment method, but correlations did not reach to explain 100 % of the variance in blinking behaviour.

Therefore, this study indicates feasibility and validity of the new method, and also indicates that results obtained by the picture-based assessment are not redundant to EMG measures.

Benefit

The new method will benefit research on the implications of the startle eye blink in such areas as cognitive science and/or human behavioural neuroscience. 

Study Design

Participants watched the middle of a computer display screen while they heard different startling acoustic stimuli through headphones. The left eye was tracked with an SMI iViewX Hi-Speed eye tracking system and the right eye muscle activity was captured with EMG.

In order to detect stress factors on the eyes, blink rates were measured based on the eye pictures delivered by the eyetracking software.  

SMI eye tracking

The SMI Hi-Speed eye tracking system delivered pictures of the eye at a high-frequency essential for the new picture-based method of measuring the startle eye blink.

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