Thomas M. Spalek

The Left-to-Right Bias in Inhibition of Return Is Due to the Direction of Reading

Previous research has shown a left-to-right bias in the inhibition-of-return effect. This bias was found in a sample of English-speaking participants who read in a predominantly left-to-right manner. The goal of the current study was to examine the role that the direction of text reading plays in this bias. The findings replicated the left-to-right bias with an English sample, but showed the opposite bias in an Arabic sample, who read text from right to left. Thus, the regularity of shifting attention in a particular way during text reading seems to be the cause of the bias observed.

Driving with the wandering mind: the effect that mind-wandering has on driving performance.

Objective: The principal objective of the present work was to examine the effects of mind state (mind-wandering vs. on-task) on driving performance in a high-fidelity driving simulator. Background: Mind-wandering is thought to interfere with goal-directed thought. It is likely, then, that when driving, mind-wandering might lead to impairments in critical aspects of driving performance. In two experiments, we assess the extent to which mind-wandering interferes with responsiveness to sudden events, mean velocity, and headway distance. Method: Using a car-following procedure in a high-fidelity driving simulator, participants were probed at random times to indicate whether they were on-task at that moment or mind-wandering. The dependent measures were analyzed based on the participant’s response to the probe. Results: Compared to when on-task, when mind-wandering participants showed longer response times to sudden events, drove at a higher velocity, and maintained a shorter headway distance. Conclusion: Collectively, these findings indicate that mind-wandering affects a broad range of driving responses and may therefore lead to higher crash risk. Application: The results suggest that situations that are likely associated with mind-wandering (e.g., route familiarity) can impair driving performance.

Attentional blink and attentional capture: endogenous versus exogenous control over paying attention to two important events in close succession.

Identification of the second of two targets is impaired if it is presented less than about 500 msec after the first. Thisattentional blink (AB) occurs under dual-task conditions in which observers are required to report both targets. AB magnitude has been estimated by subtracting the accuracy scores in the dual task from the corresponding scores in a single task in which observers are instructed to ignore the first target. Experiment 1 showed this procedure to be inappropriate, because the first target cannot be ignored. The remaining three experiments elaborated on this finding and revealed separate endogenous and exogenous sources of the second-target deficit. A parallel was drawn between the AB deficit and the deficit observed in attentional capture. Both types of deficit can be explained on the basis of a hybrid input-filtering model in which endogenous and exogenous factors are subserved by different pathways.

Supporting the attentional momentum view of IOR: Is attention biased to go right?

Inhibition of return (IOR) refers to the finding that individuals are slower to respond to a target presented at a previously attended location than they are to respond to a target presented at a novel location (Posner & Cohen, 1984). The attentional momentum theory is a recent view of how attention moves around the environment, and it provides an account for the IOR effect that does not rely on an inhibitory mechanism (Pratt, Spalek, & Bradshaw, 1999). The present paper supports the attentional momentum viewpoint in two ways: first, by replicating the finding that reaction times to targets at the uncued locations are not all the same (Pratt et al., 1999) and second, by showing that responses made to all locations on the cued side of fixation, and not just to the locations that attention had previously traversed, are slower than are responses made to locations on the opposite side of fixation. We also demonstrate that there is a directional bias to the IOR effect that results in the effect’s being larger when attention moves in a left-to-right manner.

Route familiarity breeds inattention: A driving simulator study

Inattention is a major cause of traffic accidents. Here, we show that, contrary to common-sense expectation, familiarity with a route is itself a source of driving impairment. This effect may be attributed to increased mind-wandering along familiar routes. In the present work, participants followed a vehicle along a route with which they were either familiar or unfamiliar. During the experimental session, the lead-vehicle braked at random locations, forcing participants to brake to avoid a collision. Participants were also required to respond with a button press when they noticed pedestrians heading toward the road from a sidewalk. In Experiment 1 we found that familiar drivers follow the lead vehicle more closely and are slower to notice approaching pedestrians. In Experiment 2, with following distance held constant, reaction times to central and peripheral events were longer for familiar drivers. Consistent with the mind-wandering hypothesis, all these effects were eliminated in Experiment 3 when drivers were made to focus on the driving task.

A clockwork orange: compensation opposing momentum in memory for location.

Libet, Gleason, Wright, and Pearl’s (1983; Libet, 1985) influential work using a clock-watching task suggests that voluntary actions are initiated in motor cortex prior to the point where the participant claims to have initiated that action. Joordens, van Duijn, and Spalek (2002) showed that a bias exists in this task with respect to the participants’ reports of initiation times. Joordens et al. assumed that this bias was primarily due to motion cues that are very much like those used to elicit phenomena such as representational momentum. In the present Experiment 1, it is demonstrated that this bias disappears when a mouse-click response is used in place of a temporal-order judgment. This finding, however, is actually more confusing than clarifying given that the procedural parallels with representational momentum are still present and should be supporting a bias. In the three subsequent experiments the view that a bias is indeed present, but that it is opposed by an opposite-acting compensation process, is proposed and tested. Implications for both representational momentum and for the general use of clock-watching tasks (e.g., Libet et al., 1983) are highlighted.

Attentional involvement in subitizing : Questioning the preattentive hypothesis

Subitizing, the rapid, effortless, and accurate enumeration of small numbers of items has been said to be carried out preattentively. If so, the preattentive processing could occur entirely in primary visual cortex, in which case it would be completed within about 50 ms, or during the feedforward sweep, in which case it would be completed within about 100 ms after the onset of an enumeration display which was followed by a mask. The stimulus–mask SOAs were 50 or 83 ms in Experiment 1, and 100 or 150 ms in Experiment 2. In both experiments subjects were more accurate and more sensitive to one-target than to two-target displays. These outcomes, in conjunction with the finding that accuracy and sensitivity were higher at the longer SOA, are inconsistent with the preattentive viewpoint and point to the necessity for attentional involvement in subitizing.

Perception of Temporal Order Is Impaired during the Time Course of the Attentional Blink.

Identification accuracy for the second of two target (T2) is impaired when presented shortly after the first (T1). Does this attentional blink (AB) also impair the perception of the order of presentation? In four experiments, three letter targets (T1, T2, T3) were inserted in a stream of digit distractors displayed in rapid serial visual presentation (RSVP), with T3 always presented directly after T2. The T1-T2 lag was varied to assess the perception of T2-T3 temporal order throughout the period of the AB. Factorial manipulation of the presence or absence of distractors before T1 and between T1 and T2 had similar effects on accuracy and on perception of temporal order. It is important to note that perception of temporal order suffered even when accuracy was unimpaired. This pattern of results is consistent with prior-entry theories of the perception of temporal order but not with episodic-integration theories. Simulations based on the Episodic Simultaneous Type, Serial Token (eSTST) model (Wyble, Bowman, & Nieuwenstein, 2009) provided excellent fits to the data except for the condition in which no distractors were presented in the RSVP stream.

Spatial cuing does not affect the magnitude of the attentional blink

Identification of the second of two targets is impaired when the second target is presented less than about 500 msec after the first. Nieuwenstein, Chun, van der Lubbe, and Hooge (2005, Experiment 4) reported that the magnitude of this attentional blink (AB) is reduced when the location of the second target is precued. Here we show how that finding resulted from an artifact brought about by a ceiling imposed by data limitation. Instead of using an accuracy measure, the present work used a dynamic threshold-tracking procedure that was not constrained by a performance ceiling. The results show that, when the ceiling is removed, spatial cuing does not affect and is not affected by the AB. These results are consistent with the hypothesis that cue localization and target identification may take place along separate (dorsal and ventral) visual pathways.

A novel paradigm reveals the role of reentrant visual processes in object substitution masking

Object substitution masking (OSM) occurs when an initial display of a target and mask continues with the mask alone, creating a mismatch between the reentrant hypothesis, triggered by the initial display, and the ongoing low-level activity. We tested the proposition that the critical factor in OSM is not whether the mask remains in view after target offset, but whether the representation of the mask is sufficiently stronger than that of the target when the reentrant signal arrives. In Experiment 1, a variable interstimulus interval (ISI) was inserted between the initial display and the mask alone. The trailing mask was presumed to selectively boost the strength of the mask representation relative to that of the target. As predicted, OSM occurred at intermediate ISIs, at which the mask was presented before the arrival of the reentrant signal, creating a mismatch, but not at long ISIs, at which a comparison between the reentrant signal and the low-level activity had already been made. Experiment 2, conducted in dark-adapted viewing, ruled out the possibility that low-level inhibitory contour interactions (metacontrast masking) had played a significant role in Experiment 1. Metacontrast masking was further ruled out in Experiment 3, in which the masking contours were reduced to four small dots. We concluded that OSM does not depend on extended presentation of the mask alone, but on a mismatch between the reentrant signals and the ongoing activity at the lower level. The present results place constraints on estimates of the timing of reentrant signals involved in OSM.