Limits...
Ocular accommodation and cognitive demand: an additional indicator besides pupil size and cardiovascular measures?

Jainta S, Hoormann J, Jaschinski W - J Negat Results Biomed (2008)

Bottom Line: Heart period, pulse transit time, and the pupillary response were considered as reference for possible closed-loop accommodative effects.An observed decrease in accommodation could not be attributed to the cognitive demand itself for two reasons: (1) the cognitive demand induced a shift in gaze direction which, for methodological reasons, accounted for a substantial part of the observed accommodative changes. (2) Remaining effects disappeared when the correctness of task processing was taken into account.Although the expectation of accommodation as possible autonomic indicator of cognitive demand was not confirmed, the present results are informative for the field of applied psychophysiology noting that it seems not to be worthwhile to include closed-loop accommodation in future studies.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut fuer Arbeitsphysiologie an der Universitaet Dortmund, Ardeystrasse 67, D-44139, Dortmund, Germany. jainta@ifado.de

ABSTRACT

Background: The aim of the present study was to assess accommodation as a possible indicator of changes in the autonomic balance caused by altered cognitive demand. Accounting for accommodative responses from a human factors perspective may be motivated by the interest of designing virtual image displays or by establishing an autonomic indicator that allows for remote measurement at the human eye. Heart period, pulse transit time, and the pupillary response were considered as reference for possible closed-loop accommodative effects. Cognitive demand was varied by presenting monocularly numbers at a viewing distance of 5 D (20 cm) which had to be read, added or multiplied; further, letters were presented in a "n-back" task.

Results: Cardiovascular parameters and pupil size indicated a change in autonomic balance, while error rates and reaction time confirmed the increased cognitive demand during task processing. An observed decrease in accommodation could not be attributed to the cognitive demand itself for two reasons: (1) the cognitive demand induced a shift in gaze direction which, for methodological reasons, accounted for a substantial part of the observed accommodative changes. (2) Remaining effects disappeared when the correctness of task processing was taken into account.

Conclusion: Although the expectation of accommodation as possible autonomic indicator of cognitive demand was not confirmed, the present results are informative for the field of applied psychophysiology noting that it seems not to be worthwhile to include closed-loop accommodation in future studies. From a human factors perspective, expected changes of accommodation due to cognitive demand are of minor importance for design specifications - of, for example, complex visual displays.

Show MeSH

Related in: MedlinePlus

Accommodation measures (PowerRefractor/PowerRef II). Measured refraction in the vertical pupil meridian (D; mean ± SD) as a function of measured horizontal gaze direction (deg) for the PowerRefractor and PowerRef II. Regression equations are shown separately.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2542343&req=5

Figure 9: Accommodation measures (PowerRefractor/PowerRef II). Measured refraction in the vertical pupil meridian (D; mean ± SD) as a function of measured horizontal gaze direction (deg) for the PowerRefractor and PowerRef II. Regression equations are shown separately.

Mentions: More important, the measured refraction decreased by 0.16 D (PowerRefractor) and by 0.09 D (PowerRef II) when the measured gaze direction changed by 1 deg to the right (see Figure 9). This indicated an artefact: off axis refractive errors where directly influenced by gaze direction; therefore, gaze direction should be considered in the statistical analysis of refraction data (as indicator of accommodation).


Ocular accommodation and cognitive demand: an additional indicator besides pupil size and cardiovascular measures?

Jainta S, Hoormann J, Jaschinski W - J Negat Results Biomed (2008)

Accommodation measures (PowerRefractor/PowerRef II). Measured refraction in the vertical pupil meridian (D; mean ± SD) as a function of measured horizontal gaze direction (deg) for the PowerRefractor and PowerRef II. Regression equations are shown separately.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2542343&req=5

Figure 9: Accommodation measures (PowerRefractor/PowerRef II). Measured refraction in the vertical pupil meridian (D; mean ± SD) as a function of measured horizontal gaze direction (deg) for the PowerRefractor and PowerRef II. Regression equations are shown separately.
Mentions: More important, the measured refraction decreased by 0.16 D (PowerRefractor) and by 0.09 D (PowerRef II) when the measured gaze direction changed by 1 deg to the right (see Figure 9). This indicated an artefact: off axis refractive errors where directly influenced by gaze direction; therefore, gaze direction should be considered in the statistical analysis of refraction data (as indicator of accommodation).

Bottom Line: Heart period, pulse transit time, and the pupillary response were considered as reference for possible closed-loop accommodative effects.An observed decrease in accommodation could not be attributed to the cognitive demand itself for two reasons: (1) the cognitive demand induced a shift in gaze direction which, for methodological reasons, accounted for a substantial part of the observed accommodative changes. (2) Remaining effects disappeared when the correctness of task processing was taken into account.Although the expectation of accommodation as possible autonomic indicator of cognitive demand was not confirmed, the present results are informative for the field of applied psychophysiology noting that it seems not to be worthwhile to include closed-loop accommodation in future studies.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut fuer Arbeitsphysiologie an der Universitaet Dortmund, Ardeystrasse 67, D-44139, Dortmund, Germany. jainta@ifado.de

ABSTRACT

Background: The aim of the present study was to assess accommodation as a possible indicator of changes in the autonomic balance caused by altered cognitive demand. Accounting for accommodative responses from a human factors perspective may be motivated by the interest of designing virtual image displays or by establishing an autonomic indicator that allows for remote measurement at the human eye. Heart period, pulse transit time, and the pupillary response were considered as reference for possible closed-loop accommodative effects. Cognitive demand was varied by presenting monocularly numbers at a viewing distance of 5 D (20 cm) which had to be read, added or multiplied; further, letters were presented in a "n-back" task.

Results: Cardiovascular parameters and pupil size indicated a change in autonomic balance, while error rates and reaction time confirmed the increased cognitive demand during task processing. An observed decrease in accommodation could not be attributed to the cognitive demand itself for two reasons: (1) the cognitive demand induced a shift in gaze direction which, for methodological reasons, accounted for a substantial part of the observed accommodative changes. (2) Remaining effects disappeared when the correctness of task processing was taken into account.

Conclusion: Although the expectation of accommodation as possible autonomic indicator of cognitive demand was not confirmed, the present results are informative for the field of applied psychophysiology noting that it seems not to be worthwhile to include closed-loop accommodation in future studies. From a human factors perspective, expected changes of accommodation due to cognitive demand are of minor importance for design specifications - of, for example, complex visual displays.

Show MeSH
Related in: MedlinePlus