Workload assessment for mental arithmetic tasks using the task-evoked pupillary response

Abstract

Pupillometry is a promising method for assessing mental workload and could be helpful in the optimization of systems that involve human-computer interaction. The present study focuses on replicating the studies by Ahern (1978) and Klingner (2010), which found that for three levels of difficulty of mental multiplications, the more difficult multiplications yielded larger dilations of the pupil. Using a remote eye tracker, our research expands upon these two previous studies by statistically testing for each 1.5 s interval of the calculation period (1) the mean absolute pupil diameter (MPD), (2) the mean pupil diameter change (MPDC) with respect to the pupil diameter during the pre-stimulus accommodation period, and (3) the mean pupil diameter change rate (MPDCR). An additional novelty of our research is that we compared the pupil diameter measures with a self-report measure of workload, the NASA Task Load Index (NASA-TLX), and with the mean blink rate (MBR). The results showed that the findings of Ahern and Klingner were replicated, and that the MPD and MPDC discriminated just as well between the lowest and highest difficulty levels as did the NASA-TLX. The MBR, on the other hand, did not differentiate between the difficulty levels. Moderate to strong correlations were found between the MPDC and the proportion of incorrect responses, indicating that the MPDC was higher for participants with a poorer performance. For practical applications, validity could be improved by combining pupillometry with other physiological techniques.

Cortical modulation of pupillary function: systematic review

“…Learning processes such as Pavlovian, associative learning or categorization are characterized by large pupils initially, when the cognitive load is big, and by smaller diameters when the task or item is being learned (Reinhard, Lachnit & König, 2006; Foroughi, Sibley & Coyne, 2017; Shalev et al., 2018; Reinhard & Lachnit, 2002; Van Der Meer et al., 2003; Kahya et al., 2018). Pupils also dilate in response to mental arithmetic (Steinhauer, Condray & Kasparek, 2000; Bradshaw, 1967; Chen & Epps, 2014; Marquart & De Winter, 2015; Szulewski, Roth & Howes, 2015; Szulewski et al., 2017; Steinhauer et al., 2004; Annerer-Walcher, Körner & Benedek, 2018), decision-making and visual backward masking tasks (Verney, Granholm & Dionisio, 2001; Verney, Granholm & Marshall, 2004; Schneider et al., 2018; Wolff et al., 2015; Reilly et al., 2018; Trani & Verhaeghen, 2018; Stojmenova & Sodnik, 2018; Jepma & Nieuwenhuis, 2011; Katidioti, Borst & Taatgen, 2014; Oliva & Anikin, 2018; Berthold & Slowiaczek, 1975) and they can reveal the degree of certainty during any selection process, i.e., the more undecided one is, the greater the pupillary diameter (Lempert, Chen & Fleming, 2015; Lin et al., 2017; Satterthwaite et al., 2007; Brunyé & Gardony, 2017; Geng et al., 2015).…”

Automated pupillometry to detect command following in neurological patients: a proof-of-concept study

“…Portable infrared pupillometry is a new technology that may prove useful for the determination of covert consciousness in the clinically unresponsive patient. The pupillary reflex is a polysynaptic brainstem reflex under cortical modulation, i.e., cognitive processes such as decision making and mental arithmetic produce pupillary dilation (Kahneman & Beatty, 1966; Kahneman, 1973; Loewenfeldt, 1999; Marquart & De Winter, 2015; Steinhauer, Condray & Pless, 2015; Quirins et al, 2018). Hence, pupillary responses following mental arithmetic have been used to establish communication with patients with the locked-in syndrome and to detect command-following in one patient in MCS (Stoll et al, 2013).…”

Influence of Increasing Task Complexity and Use of Informational Assistance Systems on Mental Workload

“…This study will focus on the most important indicators: pupillary response (PR), fixation duration (FD), and saccadic peak velocity (SPV) (for an overview, see [43]). With increasing cognitive or emotional load, pupil size (measured as PR) will increase [46][47][48][49]. Normal eye movements are a consecutive sequence of fixations and short volatile saccades.…”