The disruptive effects of pain on the early allocation of attentional resources: An attentional blink study.

BACKGROUND: Recent evidence suggests that pain dampens attentional processes. However, much of this work has been based on higher-order attentional tasks that involve only spatial attention. Other aspects of the process through which pain engages and holds attention are relatively understudied, in particular, temporal attention. The present set of studies explored how naturally occurring pain (i.e. acute headache) and pain-valenced stimuli affect the ability to recall the second of two targets presented in rapid succession. METHODS: Across both experiments participants were required to indicate the presence of a predefined probe (T2) and, in the dual task, identify a target (T1). The probe (T2) was placed in three different temporal proximities (ranging from 70 to 1000 ms) following presentation of the target (T1). In Experiment 1, 36 participants completed a task that comprised a rapid stream of letters. Experiment 2 manipulated the threat value, and the complexity, of the stimuli by replacing letters with words. In the dual task condition, T1 was a word from one of four valence categories (neutral, positive, negative, pain). RESULTS: Being in acute pain reduced the accuracy of identification. This reduction in performance occurred regardless of the temporal positioning of the probe, consistent with previous work that suggests pain has an overall dampening effect. Furthermore, when the valence category of the word was pain-related, T2 accuracy performance was negatively affected. CONCLUSION: These findings add to the previous evidence that pain has a general dampening effect on attention and that pain-related stimuli are difficult to disengage from. SIGNIFICANCE: Pain captures attention to allow cognate resources to be directed appropriately in response. However, the temporal effects of this attentional capture are poorly understood. Findings indicate that acute headache pain has a negative impact on participants' performance when identifying the second of two targets presented in close temporal proximity, and that pain-valenced stimuli exacerbate this effect. These findings demonstrate how pain affects early attention and highlights the potential role of disengagement, rather than orientation, of attention in the pain experience.

Strategic Eye Movements are Used to Support Object Authentication.

Authentication is an important cognitive process used to determine whether one's initial identification of an object is corroborated by additional sensory information. Although authentication is critical for safe interaction with many objects, including food, websites, and valuable documents, the visual orienting strategies used to garner additional sensory data to support authentication remain poorly understood. When reliable visual cues to counterfeit cannot be anticipated, distributing fixations widely across an object's surface might be useful. However, strategic fixation of specific object-defining attributes would be more efficient and should lead to better authentication performance. To investigate, we monitored eye movements during a repetitive banknote authentication task involving genuine and counterfeit banknotes. Although fixations were distributed widely across the note prior to authentication decisions, preference for hard-to mimic areas and avoidance of easily mimicked areas was evident. However, there was a strong tendency to initially fixate the banknote's portrait, and only thereafter did eye movement control appear to be more strategic. Those who directed a greater proportion of fixations at hard-to-mimic areas and resisted more easily mimicked areas performed better on the authenticity task. The tendency to deploy strategic fixation improved with experience, suggesting that authentication benefits from precise visual orienting and refined categorisation criteria.

The utility of multiple synthesized views in the recognition of unfamiliar faces.

The ability to recognize an unfamiliar individual on the basis of prior exposure to a photograph is notoriously poor and prone to errors, but recognition accuracy is improved when multiple photographs are available. In applied situations, when only limited real images are available (e.g., from a mugshot or CCTV image), the generation of new images might provide a technological prosthesis for otherwise fallible human recognition. We report two experiments examining the effects of providing computer-generated additional views of a target face. In Experiment 1, provision of computer-generated views supported better target face recognition than exposure to the target image alone and equivalent performance to that for exposure of multiple photograph views. Experiment 2 replicated the advantage of providing generated views, but also indicated an advantage for multiple viewings of the single target photograph. These results strengthen the claim that identifying a target face can be improved by providing multiple synthesized views based on a single target image. In addition, our results suggest that the degree of advantage provided by synthesized views may be affected by the quality of synthesized material.

Attentional modulation of the carry over of eye-movements between tasks.

Task demands that influence scanning behaviour in one task can cause that behaviour to persist to a second unrelated task (carry over). This can also affect performance on a second task (e.g., hazard perception ratings), and has been attributed to a process of attentional bias that is modulated by top-down influences (Thompson & Crundall, 2011). In a series of experiments we explored how these top-down influences impact upon carry over. In all experiments, participants searched letters that were presented horizontally, vertically, or in a random array. They were then presented with a driving scene and rated the hazardousness of the scene. Carry over of eye-movements from the letter search to the scene was observed in all experiments. Furthermore, it was demonstrated that this carry over effect influenced hazard perception accuracy. The magnitude of carry over was correlated with task switching abilities, attentional conflicting, and attentional orienting (Experiment 1), and was affected by predictability of the primary task (Experiment 2). Furthermore, direct current stimulation of the left dorsolateral prefrontal cortex and parietal areas affected the magnitude of the effect (Experiment 3). These results indicate that carry over is modulated by the specific ability to orient attention and disengage from this orientation. Over orienting leads to increased carry over and insufficient task switching is detrimental to task performance. As a result the current experiments provide evidence that the carry over effect is strongly influenced by attentional processes, namely orienting, inhibition, and task switching.

Learning faces: similar comparator faces do not improve performance.

Recent evidence indicates that comparison of two similar faces can aid subsequent discrimination between them. However, the fact that discrimination between two faces is facilitated by comparing them directly does not demonstrate that comparison produces a general improvement in the processing of faces. It remains an open question whether the opportunity to compare a "target" face to similar faces can facilitate the discrimination of the exposed target face from other nonexposed faces. In Experiment 1, selection of a target face from an array of novel foils was not facilitated by intermixed exposure to the target and comparators of the same sex. Experiment 2 also found no advantage for similar comparators (morphed towards the target) over unmorphed same sex comparators, or over repeated target exposure alone. But all repeated exposure conditions produced better performance than a single brief presentation of the target. Experiment 3 again demonstrated that repeated exposure produced equivalent learning in same sex and different sex comparator conditions, and also showed that increasing the number of same sex or different sex comparators failed to improve identification. In all three experiments, exposure to a target alongside similar comparators failed to support selection of the target from novel test stimuli to a greater degree than exposure alongside dissimilar comparators or repeated target exposure alone. The current results suggest that the facilitatory effects of comparison during exposure may be limited to improving discrimination between exposed stimuli, and thus our results do not support the idea that providing the opportunity for comparison is a practical means for improving face identification.

Perceptual learning with complex visual stimuli is based on location, rather than content, of discriminating features.

Exposure to complex checkerboards (comprising a common background, e.g., X, with unique features, e.g., A-D, that are placed in particular locations on the background) improves discrimination between them (perceptual learning). Such stimuli have been used previously to probe human perceptual learning but these studies leave open the question of whether the improvement in discrimination is based on the content or location of the unique stimuli. Experiment 1 suggests that perceptual learning produced by exposure to AX and BX transferred to stimuli that had new unique features (e.g., C, D) in the position that had been occupied by A and B during exposure. However, there was no transfer to stimuli that retained A and B as the unique features but moved them to a different location on the background. Experiment 2 replicated the key features of Experiment 1, that is, no transfer of exposure learning based on content but perfect transfer of exposure learning based on location using a design which allowed for independent tests of location- and content-based performance. In both the experiments reported here, superior discrimination between similar stimuli on the basis of exposure can be explained entirely by learning where to look, with no independent effect of learning about particular stimulus features. These results directly challenge the interpretation of practically all prior experiments using the same type of design and stimuli.