Measuring effects of voluntary attention: a comparison among predictive arrow, colour, and number cues

The Active Suppression of a Distractor's Location Can Be Elusive

Our visual system is inundated with distracting objects that vie for our attention. While visual attention selects relevant information, inhibitory mechanisms might be useful to suppress the locations occupied by irrelevant distractors. Yet, there is a dearth of behavioral evidence for the active suppression of a distractor's location (ASDL) using central cues that provide preliminary information about a distractor's location. In the first two experiments, we attempt to conceptually replicate, using an online platform, experiments that provide evidence of the ASDL. We replicate the distractor cueing effect in a localization task (Experiment 1) wherein responses to targets were faster when a central arrow cued the location of an impending distractor than an empty location. This effect was larger in the first block of trials than it was in the second. In a discrimination task (Experiment 2), unlike previous studies, we found no evidence for an effect of distractor cueing. In Experiment 3, we replaced the central arrow cues with central number cues because arrow cues may elicit a symbolic shift of attention that might offset the ASDL. Once again, the best model was one in which the distractor cueing effect was absent. We replicate these failures to find evidence of the ASDL in two more experiments. The results suggest that the ASDL can be elusive and may be tied to the response system, not attention.

EXPRESS: Can arrows change the subjective perception of space? Exploring symbolic attention repulsion

The attention repulsion effect (ARE) refers to distortions in the perception of space for areas nearby the focus of attention. For instance, when attending to the right-hand side of the visual field, objects in central vision may appear as though they are shifted to the left. The phenomenon is likely caused by changes in visual cell functioning. To date, research on the ARE has almost exclusively used exogenous manipulations of attention. In contrast, research exploring endogenous attention repulsion has been mixed, and no research has explored the effects of non-predictive arrow cues on this phenomenon. This gap in the literature is unexpected, as symbolic attention appears to be a unique form of attentional orienting compared to endogenous and exogenous attention. Therefore, the current study explored the effects of symbolic orienting on spatial repulsion and compared it to an exogenously generated ARE. Across four experiments, both exogenous and symbolic orienting resulted in AREs; however, the magnitude of the symbolic ARE was smaller than the exogenous ARE. This difference in magnitude persisted, even after testing both phenomena using stimulus timing parameters known to produce optimal effects in traditional attentional cueing paradigms. Therefore, compared to symbolic attention, it appears that exogenous manipulations may tightly constrict attention resources on the cued location, in turn potentially influencing the functioning of visual cells for enhanced perceptual processing.

No effect of spatial attention on the processing of a motion ensemble: Evidence from Posner cueing

The formation of ensemble codes is an efficient means through which the visual system represents vast arrays of information. This has led to the claim that ensemble representations are formed with minimal reliance on attentional resources. However, evidence is mixed regarding the effects of attention on ensemble processing, and researchers do not always make it clear how attention is being manipulated by their paradigm of choice. In this study, we examined the effects of Posner cueing - a well-established method of manipulating spatial attention - on the processing of a global motion stimulus, a naturalistic ensemble that requires the pooling of local motion signals. In Experiment 1, using a centrally presented, predictive attentional cue, we found no effect of spatial attention on global motion performance: Accuracy in invalid trials, where attention was misdirected by the cue, did not differ from accuracy in valid trials, where attention was directed to the location of the motion stimulus. In Experiment 2, we maximized the potential for our paradigm to reveal any attentional effects on global motion processing by using a threshold-based measure of performance; however, despite this change, there was again no evidence of an attentional effect on performance. Together, our results show that the processing of a global motion stimulus is unaffected when spatial attention is misdirected, and speak to the efficiency with which such ensemble stimuli are processed.

Attention Combines Similarly in Covert and Overt Conditions

Attention is classically classified according to mode of engagement into voluntary and reflexive, and type of operation into covert and overt. The first distinguishes whether attention is elicited intentionally or by unexpected events; the second, whether attention is directed with or without eye movements. Recently, this taxonomy has been expanded to include automated orienting engaged by overlearned symbols and combined attention engaged by a combination of several modes of function. However, so far, combined effects were demonstrated in covert conditions only, and, thus, here we examined if attentional modes combined in overt responses as well. To do so, we elicited automated, voluntary, and combined orienting in covert, i.e., when participants responded manually and maintained central fixation, and overt cases, i.e., when they responded by looking. The data indicated typical effects for automated and voluntary conditions in both covert and overt data, with the magnitudes of the combined effect larger than the magnitude of each mode alone as well as their additive sum. No differences in the combined effects emerged across covert and overt conditions. As such, these results show that attentional systems combine similarly in covert and overt responses and highlight attention's dynamic flexibility in facilitating human behavior.

Combined attention controls complex behavior by suppressing unlikely events

Attention enables behavior by modulating both sensory inputs and task goals. Combining attentional resources from both of those sources exerts qualitatively large effects on manual performance. Here we tested how combined attention was represented in sensory processing, as reflected by the P1 component and associated activity in the alpha band. We measured performance and recorded EEG while participants' attention was engaged in an automated, endogenous, and combined (i.e., automated and endogenous) manner. Behavioral results replicated past reports with reliable effects of isolated automated and endogenous attention, as well as their qualitatively unique combined effect. ERP analyses indicated expected increases in P1 amplitude for validly relative to invalidly cued targets in automated and endogenous conditions. However, in the combined case, the P1 difference between validly relative to invalidly cued targets decreased. Analyses of target-locked alpha-band further revealed that this condition was associated with an increased synchrony in the alpha frequency for invalidly cued targets. This suggests that the large performance benefit observed when attentional systems combine is partly driven by suppressed processing of unexpected targets, dovetailing with the notion that in addition to increasing sensory gain of attended targets, attention may also modulate complex behavior by increasing suppression of unattended ones.

If not When, then Where? Ignoring Temporal Information Eliminates Reflexive but not Volitional Spatial Orienting

A tremendous amount of research has been devoted to understanding how attention can be committed to space or time. Until recently, relatively little research has examined how attention to these two domains combine. The present study addressed this issue. We examined how implicitly manipulating whether participants used a cue to orient attention in time impacts reflexive or volitional shifts in spatial attention. Specifically, participants made speeded manual responses to the detection of a peripherally presented target that appeared either 100, 500, or 1000 ms after the onset of a central cue. Cues were either spatially non-predictive arrows (p = 0.50) or spatially-predictive (p = 0.80) letter cues. Whereas arrow cues can reflexively orient spatial attention even when non-predictive of a target’s spatial location, letters only orient spatial attention when they reliably predict a target location, i.e., the shift is volitional. Further, in one task, a target was presented on every trial, thereby encouraging participants to use the temporal information conveyed by the cue to prepare for the appearance of the target. In another task, 25% of trials contained no target, implicitly discouraging participants from using the cue to direct attention in time. Results indicate that when temporal information is reliable and therefore volitionally processed, then spatial cuing effects emerge regardless of whether attention is oriented reflexively or volitionally. However, when temporal information is unreliable, spatial cuing effects only emerge when spatial cue information is reliable, i.e., when spatial attention is volitionally shifted. Reflexive cues do not elicit spatial orienting when their temporal utility is reduced. These results converge on the notion that reflexive shifts of spatial attention are sensitive to implicit changes in a non-spatial domain, whereas explicit volitional shifts in spatial attention are not.

Resolving the controversy of the proportion validity effect: Volitional attention is not required, but may have an effect

Response time (RT) is facilitated when a target appears at a cued (valid) location versus an uncued (invalid) location. Interestingly, this valid-versus-invalid RT difference increases as the percentage of valid trials increases. In the present study, we investigated the mechanism responsible for this proportion valid cueing effect (PVE). The PVE is thought to reflect changes in voluntary attentional allocation, with greater attention being committed endogenously to the cued location as the percentage of valid trials increases. However, recent research has suggested that the PVE may reflect a form of implicit learning between the cue and the target location that is developed outside of awareness, and that this determines how attention is allocated. This lack of convergence may be due to methodological differences in how voluntary processing has been inferred. To test this issue, we generated a method that would allow the measurement of different degrees of volitional attention. In addition, we manipulated whether participants were instructed to attend to the cue-target relationship and determined whether this explicit engagement of attention influenced the PVE. We found that for both peripheral and central cues, volitional control is not required for a PVE; however, volitional control can modulate a PVE that is produced by central cues. Thus, a PVE is not a reliable indicator of volitional control, but its sensitivity to volitional control varies across cues. The present data shed light on the mechanism subserving the PVE and lend support to the theory that different cues engage, to some degree, qualitatively different forms of visuospatial attention.

DOES DYSLEXIA DEVELOP FROM LEFT-EYE DOMINANCE?

The purpose of this theoretical analysis and synthesis is to indicate how left-eye sighting dominance may lead to reading failure through dysfunctional right hemisphere letter encoding. Differing compensatory strategies are postulated to lead to outcomes that include the development of the phonologically impaired and phonologically proficient subtypes of dyslexia as well as specific spelling disability. Evidence is presented indicating that these disorders might be prevented by delaying the introduction of letter writing until the age of 8 years. Early childhood speech categorization in children genetically at-risk of developing dyslexia is also considered from this perspective. Convergent support for this premature writing hypothesis is provided by a comparison with the development of the left-hand inverted writing posture.