James Head

Reliable- and unreliable-warning cues in the Sustained Attention to Response Task

The Sustained Attention to Response Task (SART) is a Go-No-Go signal detection task developed to measure lapses of attention. In this study, we examined the impact that warning signals, reliable and unreliable, have on SART performance. Eighteen participants performed a no-warning, reliable-warning, or unreliable-warning SART. Response times were faster, errors of commission lower, but errors of omission higher in the reliable-warning SART in comparison with the no-warning or unreliable-warning SART. There was a significant negative correlation between participants’ errors of commission rate and their response times in the unreliable-warning and no-warning SART. This correlation was reduced in the reliable-warning SART. Making the task perceptually easier reduces the errors of commission, in contradiction to the mindlessness perspective, and reduces the speed-accuracy trade-off. These results, overall, support the view that the SART is primarily a measure of response strategy, not sustained attention per se.

Natural scene stimuli and lapses of sustained attention

We conducted two experiments using naturalistic scene stimuli to test the resource theory and mindlessness theory of sustained attention. In experiment 1, 28 participants completed a traditional formatted vigilance task consisting of non-repeating forest or urban picture stimuli as target stimuli. Participants filled out pre- and post-task assessments of arousal and conscious thoughts. There was still a vigilance decrement, despite non-repetitive, natural target stimuli. Participants found the task demanding and were actively engaged in the task. In experiment 2, 25 participants completed a Sustained Attention to Response Task (SART) using the stimuli from experiment 1. Participants performed significantly worse on this SART than either brain injury patients or controls performing equivalent numeric stimuli SARTs have in previous studies. Participants thought the task was demanding and they were actively engaged with the task. Overall, the results of both studies support a resource theory of sustained attention lapses, not a mindlessness theory.

Perceptual decoupling or motor decoupling

The current investigation was conducted to elucidate whether errors of commission in the Sustained Attention to Response Task (SART) are indicators of perceptual or motor decoupling. Twenty-eight participants completed SARTs with motor and perceptual aspects of the task manipulated. The participants completed four different SART blocks whereby stimuli location uncertainty and stimuli acquisition were manipulated. In previous studies of more traditional sustained attention tasks stimuli location uncertainty reduces sustained attention performance. In the case of the SART the motor manipulation (stimuli acquisition), but not the perceptual manipulation (stimuli location uncertainty) significantly reduced commission errors. The results suggest that the majority of SART commission errors are likely to be indicators of motor decoupling not necessarily perceptual decoupling.

Sustained attention failures are primarily due to sustained cognitive load not task monotony.

We conducted two studies using a modified sustained attention to response task (SART) to investigate the developmental process of SART performance and the role of cognitive load on performance when the speed-accuracy trade-off is controlled experimentally. In study 1, 23 participants completed the modified SART (target stimuli location was not predictable) and a subjective thought content questionnaire 4 times over the span of 4 weeks. As predicted, the influence of speed-accuracy trade-off was significantly mitigated on the modified SART by having target stimuli occur in unpredictable locations. In study 2, 21 of the 23 participants completed an abridged version of the modified SART with a verbal free-recall memory task. Participants performed significantly worse when completing the verbal memory task and SART concurrently. Overall, the results support a resource theory perspective with concern to errors being a result of limited mental resources and not simply mindlessness per se.

Natural disaster induced cognitive disruption: Impacts on action slips

Previous research has indicated an increase in stress levels and cognitive intrusions after natural disasters. These previous studies have not, however, assessed the impact disaster induced cognitive disruption has on human performance. In the present report, we investigated the impact of the 7.1 magnitude 2010 Christchurch, New Zealand earthquake on self-reported earthquake-induced cognitive disruption and its relationship to performance on the Sustained Attention to Response Task (SART). Participants who self-reported greater cognitive disruption induced by the earthquake also had higher levels of errors of commission during SART (r=.80, p<.001). This was even the case when controlling for earthquake-induced anxiety, depression, participant sex, and self-reported sleep amount. Post-disaster assessments need to include the impact of the events directly on cognitive self-regulation and conscious thoughts, in addition to more clinical constructs, such as anxiety and depression.

Text-speak processing and the sustained attention to response task

We examined performance in a sustained attention to response task (SART) (Experiment 1) and a more traditionally formatted vigilance task (Experiment 2) using novel word stimuli (text-speak) and normally spelt words. This enabled us to address whether the SART is a better measure of sustained attention or of response strategy, and to investigate the cognitive demands of text-speak processing. In Experiment 1, 72 participants completed a subset (text-speak) and a word SART, as well as a self-reported text experience questionnaire. Those who reported more proficiency and experience with text-speak made more errors on the subset SART, but this appeared to be due to their increase in response speed. This did not occur in the word SART. In Experiment 2, 14 participants completed high No-Go, low-Go (more traditional response format) versions of these tasks to further investigate the cognitive demands of text-speak processing. Response latency increased over periods of watch only for the text-speak task, not for the word task. The results of Experiment 1 support the perspective that the SART is highly sensitive to response strategy, and the results of both experiments together indicate target detection tasks may be a novel way of investigating the cognitive demands of text-speak processing.

Earthquakes on the Mind: Implications of Disasters for Human Performance

Objective: The present study explored the impact a natural disaster has on human performance. Background: Previous research indicates that traffic accidents increase after disasters. A plausible explanation for this finding is that disasters induce cognitive disruption and this disruption negatively affects performance (e.g., driving quality). Method: A total of 16 participants (7 men and 9 women) performed a sustained-attention-to-response task before and after a 7.1-magnitude earthquake. Performance (errors of omission, errors of commission, and reaction time) was compared before and after the earthquake. Results: Errors of omission increased after the earthquake. Changes in errors of commission and reaction times were, however, dependent on individual differences in stress response to the earthquake. Conclusion: The results indicate that natural disasters may have a negative impact on performance. Application: Communities need to be aware of the increased risk of accidents following disasters and develop countermeasures, including individualized assessment tools.

Practice does not make perfect in a modified sustained attention to response task

In the current investigation, we examined the changes in performance, task-related thoughts (TRT), and task-unrelated thoughts (TUT) over four sessions of a modified sustained attention to response task (SART). Eighteen participants completed a clockwise manual selection SART (Head and Helton in Conscious Cogn 22:913–919, 2013) and a conscious thought questionnaire once a week for four weeks. Response times and errors of commission oscillated over sessions in line with a motor strategy interpretation of the SART. As participants became faster in the task, they made more commission errors. The conscious thought questionnaire failed to show a relationship between errors of commission and TRT and TUT on the SART at either a between-subject or within-subject level of analysis. Commission errors in the SART may be better measures of executive motor control and response strategy than perceptual decoupling.

Friendly Fire in a Simulated Firearms Task

Factors such as poor visibility, lack of situation awareness, and bad communication have been shown to contribute to friendly fire incidents. However, to the authors’ knowledge, an individual’s ability to inhibit their motor response of shooting when a non-target is presented has not been investigated. This phenomenon has been modeled empirically using the Sustained Attention to Response Task (SART; Robertson, Manly, Andrade, Baddeley, & Yiend, 1997) computer task. The SART is generally a high Go/low No-Go detection task whereby participants respond to numerous neutral stimuli and withhold to rare targets. In the current investigation, we further investigate the SART using a simulated small arms scenario to test whether lack of motor response inhibition can be modeled in a more ecologically valid environment. Additionally, we were interested in how error rates were impacted in low Go/high No-Go versions of the task. Thirteen university students completed a computer and simulated small arms scenario in a SART and low Go condition. Both the computer and small arms scenario revealed similar speedaccuracy trade-offs indicating participants’ inability to halt their pre-potent responses to targets even in a more ecologically valid environment. The SART may be used in future studies to model friendly fire scenarios.

Friendly Fire and the Sustained Attention to Response Task

Objective: We investigated whether losses of inhibitory control could be responsible for some friendly-fire incidents. Background: Several factors are commonly cited to explain friendly-fire incidents, but failure of inhibitory control has not yet been explored. The Sustained Attention to Response Task (SART) could be a valid model for inhibition failures in some combat scenarios. Method: Participants completed small-arms simulations using near infrared emitter guns, confronting research assistants acting as friends or foes. In Experiment 1, seven participants completed three conditions with three different proportions of foes (high, medium, low). In Experiment 2, 13 participants completed high-foe (high-go) and low-foe (low-go) versions of a small-arms simulation as well as comparative computer tasks. Results: Participants made more friendly-fire errors (errors of commission) when foe proportion was high. A speed–accuracy trade-off was apparent, with participants who were faster to fire on foes also more likely to accidentally shoot friends. When foe proportion was higher, response times to foe stimuli were faster, and subjective workload ratings were higher. Conclusion: Failures of inhibitory control may be responsible for some friendly-fire incidents and the SART could be a suitable empirical model for some battlefield environments. The effect appears to be disproportionately greater at higher foe proportions. The exact nature of performance reductions associated with high-foe proportions requires further investigation. Application: The SART may be a useful model of friendly-fire scenarios. It could be used to indicate a soldier’s likelihood to commit a friendly-fire mistake and to identify high-risk environments.