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Psychophysiological Measures of Workload: Potential Applications to Adaptively Automated Systems
Published in Raja Parasuraman, Mustapha Mouloua, Automation and Human Performance: Theory and Applications, 2018
Arthur F. Kramer, Leonard J. Trejo, Darryl G. Humphrey
Given the multidimensional nature of mental workload and other psychological constructs (e.g., memory, attention, language processes), it is fortunate that ERP components, which are defined with respect to their polarity, scalp distribution, and latency range, have been found to be sensitive to a variety of different information processing activities. For example, the P100 component, a positive going voltage deflection that occurs within 100 milliseconds following a stimulus, is specifically sensitive to the allocation of attention to a particular region of the visual field. The mismatch negativity (MMN), which is a negative going difference wave that occurs approximately 150 to 250 milliseconds poststimulus, provides an index of the extent to which a particular stimulus matches a predefined template (e.g., Is that the musical note I heard a few seconds ago?). The P300 component appears to reflect stimulus evaluation processing, whereas the N400 component reflects the detection of semantic mismatch. Thus, one advantage of psychophysiological measures, and ERPs in particular, is that they are inherently multidimensional in nature. That is, the components that can be found in a single one-second waveform reflect a multitude of information processing activities.
Psychophysiological assessment of workload in multi-task environments
Published in Diane L. Damos, Multiple-task performance, 2020
Glenn F. Wilson, F. Thomas Eggemeier
Theissen et al. (1986) also employed the oddball technique in several studies performed in a fighter aircraft simulator. These studies produced both positive results and findings that suggest some caution in applications of the oddball paradigm to high workload multi-task environments. One study that involved electronic-warfare officers produced P300 responses to visually presented oddball or rare event stimuli. These responses demonstrated differences between a single-task rare event control condition and simulated flight conditions, but did not differ significantly as a function of flight conditions involving air-to-ground weapons delivery. Difficulty levels were varied by manipulating variables such as target characteristics (e.g., number and type) and threats to the aircraft. In an additional study, however, pilots were required to discriminate frequent from infrequent tones as part of the oddball procedure. Moderate to high levels of workload were associated with failures to respond to a high proportion of infrequent tones with an associated inability to obtain P300 responses. The secondary task used to elicit EPs was not part of the normal simulator tasks and the lack of both EP and performance responses at moderate to high workload levels indicates that this sort of secondary-task strategy may not be appropriate for complex multiple-task environments such as flight. Wilson et al. (1982) reported similar difficulties in an A-10 aircraft simulator study designed to assess emergency procedures. Relevant, naturally occurring eliciting stimuli, or the use of other physiological measures, may be required in those high workload situations. This first strategy has been used by Biferno (1985) in a part-task flight simulation. He used a relevant, naturally occurring eliciting stimulus – the subject’s radio call sign – as an auditory probe to elicit EPs, and found P300 and N400 amplitudes to be related to subject workload and fatigue ratings. This relevant probe paradigm should be further investigated to determine its application, since it may overcome the problem of pilots ignoring ‘artificial’ task stimuli.
Effect of emoji prime on the understanding of emotional words – evidence from ERPs
Published in Behaviour & Information Technology, 2022
Jiayi Yang, Yingxi Yang, Lichao Xiu, Guoming Yu
Some ERPs components can be used to probe into the effect of emojis. N1 and P2 are related to early perceptual processing, attention orienting, and late elaborate processing. N1 is the first negative-going component around 80–150 milliseconds post-stimulus. It can serve as an index of a discrimination process, which includes selective attention to the stimuli (Vogel and Luck 2000). P2 is a positive going electrical potential that peaks at about 150-220 ms. Its amplitude will increase as extraneous stimulus appears, and is related to the allocation of attentional resources (Yang et al. 2012; Key, Dove, and Maguire 2005), the level of complexity of the information (Pernet et al. 2003) and the valence of the given words (Olofsson and Polich 2007). N400, which is a negative-going deflection that peaks around 400 milliseconds post-stimulus onset (Kutas and Hillyard 1980), is also an important component related to semantic priming (Ströberg, Andersen, and Wiens 2017). Although the functional significance of the N400 effect is not agreed upon, it is generally thought to indicate the difficulty of semantic processing (Luck 2005), or the cognitive resources demanded in semantic processing (Kutas and Federmeier 2011). Moreover, the N400 reflects semantic integration within a larger context created by expectations on contents (Kissler, Assadollahi, and Herbert 2006). Its amplitude reflects the difficulty of semantic processing, in that the greater the predictability of the target words, the smaller the amplitude of the N400 elicited (Kiefer et al. 1998; Steinhauer et al. 2017; Van Petten 1995). In this study’s case, different emoji-word semantic relationships create different contexts, in which the N400 amplitudes demonstrate different levels of cognitive resources demanded to process the words.
Subliminal Techniques: Considerations and Recommendations for Analyzing Feasibility
Published in International Journal of Human–Computer Interaction, 2018
Mary L. Still, Jeremiah D. Still
Importantly, there is evidence that subliminal stimuli also require processing resources to be effective. Naccache, Blandin, and Dehaene (2002) asked participants to complete a number-comparison task, where they were presented with a number and then had to determine if that number was higher or lower than a comparison number. For instance, the participant might be presented with an 8 and they have to decide if it is lower or higher than 5. Before the target, participants are presented with a prime that is congruent or incongruent with the target response. The entire sequence of events was embedded in a stream of visual masks so that there was a series of visual events appearing at the same location on the screen. Naccache et al. (2002) were able to vary participant temporal attention by manipulating the position of the prime and the target in the visual stream, by using external cues to exogenously engage attention, and by using the word primes early and late to direct attention. Across a series of experiments, the only significant priming effects were obtained when attention was directed toward the stimuli. In another masked priming experiment, Kiefer and Brendel (2006) found evidence that attention to the subliminal stimulus modulates the impact of that stimulus. In their experiment, the subliminal stimulus was a briefly presented, masked word that was either semantically related or unrelated to a subsequent target word. When the meaning of a word is accessed, a specific event-related potential (ERP) component, the N400, is elicited. Attention to the subliminal word was manipulated by changing the timing of events during the trial; specifically, the delay between the mask and the prime was either longer or shorter. Less attention is directed to the prime when there is a longer pause between the mask and the prime. The results of this study found that when temporal attention is not directed toward the prime, no N400 was elicited. Based on these results, diverting attentional resources from a subliminal stimulus reduces its effectiveness; by proxy, this suggests that, at minimum, temporal attention is required to effectively process subliminal stimuli. With this knowledge, it is clear that researchers should consider the type of resources that may be required to process the subliminal stimulus and how that might interact with ongoing task demands.
Applying Functional Animation to Pictorial Symbols for Supporting P300–Brain–Computer Interface Access to Augmentative and Alternative Communication Devices by Children
Published in International Journal of Human–Computer Interaction, 2022
Kevin M. Pitt, Zachary J. Cole, Joshua Zosky
Alongside previously discussed ERP components, elicitation of the N400 ERP may be targeted to boost P300-BCI-AAC performance (Kaufmann et al., 2013; Pitt et al., 2019a). The N400 ERP is associated with congruency, processing effort, and access to lexical content, such as semantic priming (e.g., Kutas & Federmeier, 2011; Kutas & Hillyard, 1980; Mehta et al., 2009) where an individual generates, or primes, congruent vocabulary semantically related to a target word (e.g., lemon may prime the term sour; Hill et al., 2002). Pictorial symbol motion may increase symbol transparency and depiction of object characteristics (e.g., the television turning on, the flower growing) in a more enriching manner than static images. Therefore, this enriched depiction was hypothesized to increase lexical access and semantic priming, enhancing processing efforts and N400 ERP amplitudes for the animation condition. However, in contrast to our hypothesis, the static condition produced significantly greater N400 ERP amplitudes and reduced latency within the parieto-occipital bin. The underlying reason for a smaller N400 response to the animation, in comparison to the static condition, is unclear. However, prior research has noted that motion may increase the positivity of ERP amplitudes during the N400 time period. For instance, while our N400 amplitude finding did not reach positivity (MAnimation = −2.19), in an analysis of ERPs underlying a motion-based BCI-AAC speller, Hong et al. (2009) identified a late positive component. This late positive component was possibly due to mechanisms associated with target identification. Further, while both conditions were matched for highlighting duration, the static condition was unchanging in nature, and only the pictorial stimuli in the functional animation condition were continually changing for the full 800 ms duration. Therefore, there is potential that the N400 ERP component was obscured by continued processing of moving stimuli, which was associated with a statistically significant increase in the motion-related P200/P300 positivity immediately preceding N400-related processing. Similar to the P200/P300, further research is needed to disambiguate the P200/P300 and N400 ERPs within our study, possibly by use of independent components analysis (Mehta et al., 2009). Finally, the participant sample for our investigation consisted of healthy children with typical language skills, who may only experience minimal benefits from motion on semantic priming processes (Vivian et al., 2012). Thus, further research is needed into the effects of symbol animation and language abilities on the N400 ERP to help bolster BCI-AAC performance.