Even when an illegal user steals the speckle phase mask, the system cannot be broken into without the correct pupil geometrical parameters.
During sentence reading, the corrected pupil data does not show a pupil size change from -17° to -13°.
The corrected pupil data, however, indicated a dilatation from around 200 ms until it flattened at around 1,200 ms.
As was expected, the resulting corrected pupil response does not show any significant change in pupil size (see Fig. 1c, circle symbols; MSE = 52 pixels).
The corrected pupil response showed the typical dilation of the pupil, with maximum dilation being reached around 1,200 ms after the presentation of the stimulus.
The study furthermore provides an approach for correcting this influence of gaze position, and the corrected pupil responses will allow more precise cognitive interpretations in future pupillometry studies.
Finally, uncorrected and corrected pupil sizes are shown relative to the time from the appearance of the sentence onward (Fig. 3).
A comparison of the corrected pupil response (Fig. 1c, triangle symbols) with the uncorrected pupil response (Fig. 1a, triangle symbols) reveals that both correction approaches altered the pupil response substantially.
This corrected pupil response corresponds to pupil responses reported by studies that investigated the reading of isolated words (Briesemeister et al., 2009; Kuchinke et al., 2007; Võ et al., 2008).
Importantly, the larger pupil size during sentence reading than during z-string scanning that was reported for the uncorrected data above was also found for the corrected data: A comparison of the corrected pupil response reveals a significantly wider pupil for sentence reading than for the z-string scanning from about -10.5° onward (all ts > 2.1, all ps <.05).
