Recurrence quantification analysis of eye movements

Recurrence quantification analysis (RQA) has been successfully used for describing dynamic systems that are too complex to be characterized adequately by standard methods in time series analysis. More recently, RQA has been used for analyzing the coordination of gaze patterns between cooperating individuals. Here, we extend RQA to the characterization of fixation sequences, and we show that the global and local temporal characteristics of fixation sequences can be captured by a small number of RQA measures that have a clear interpretation in this context. We applied RQA to the analysis of a study in which observers looked at different scenes under natural or gaze-contingent viewing conditions, and we found large differences in the RQA measures between the viewing conditions, indicating that RQA is a powerful new tool for the analysis of the temporal patterns of eye movement behavior.     

A role for set in the control of automatic spatial response activation

Spatial stimulus-response (S-R) compatibility effects are widely assumed to reflect the automatic activation of a spatial response by the spatial attributes of a stimulus. The experiments reported here investigate the role of the participant's set in enabling or interacting with this putatively automatic spatial response activation. Participants performed a color discrimination task (Experiment 1) or a localization task (Experiment 2). In each experiment, two different S-R mappings were used and a task-cue indicated the appropriate mapping on each trial. S-R compatibility and the time between the task-cue and target were manipulated, and compatibility effects were assessed as a function of (a) the time between the task-cue and the stimulus, and (b) whether the S-R mapping repeated or switched on consecutive trials. Critically, whether response mappings repeated or switched on consecutive trials determined the relation between compatibility effects and the time between task-cue and stimulus. These results are discussed in terms of an interaction between automatic spatial response activation and the participant's set.     

Exploiting human sensitivity to gaze for tracking the eyes

Given the prevalence, quality, and low cost of web cameras, along with the remarkable human sensitivity to gaze, we examined the accuracy of eye tracking using only a web camera. Participants were shown webcamera recordings of a person’s eyes moving 1°, 2°, or 3° of visual angle in one of eight radial directions (north, northeast, east, southeast, etc.), or no eye movement occurred at all. Observers judged whether an eye movement was made and, if so, its direction. Our findings demonstrate that for all saccades of any size or direction, observers can detect and discriminate eye movements significantly better than chance. Critically, the larger the saccade, the better the judgments, so that for eye movements of 3°, people can tell whether an eye movement occurred, and where it was going, at about 90% or better. This simple methodology of using a web camera and looking for eye movements offers researchers a simple, reliable, and cost-effective research tool that can be applied effectively both in studies where it is important that participants maintain central fixation (e.g., covert attention investigations) and in those where they are free or required to move their eyes (e.g., visual search).     

Offloading memory: Serial position effects

Psychonomic Bulletin & Review - Despite the long history and pervasiveness of cognitive offloading as a memory strategy, the memorial fate of offloaded information is not well understood....     

Spatial attention modulates feature crosstalk in visual word processing

One major idea about spatial attention is that it serves to modulate crosstalk between features during reading. Two reading aloud experiments are reported in which a cue-validity manipulation was combined with manipulations that are thought to increase the likelihood of feature-level crosstalk: interletter spacing and the presence or absence of irrelevant features. Both experiments yielded an interaction between the effects of spatial cuing and each of these factors. These results are taken to support the hypothesis that when spatial attention is focused on the word, it provides protection against crosstalk among features in the context of reading aloud.     

Challenging the reliability and validity of cognitive measures: The case of the numerical distance effect

The numerical distance effect (NDE) is one of the most robust effects in the study of numerical cognition. However, the validity and reliability of distance effects across different formats and paradigms has not been assessed. Establishing whether the distance effect is both reliable and valid has important implications for the use of this paradigm to index the processing and representation of numerical magnitude in both behavioral and neuroimaging studies. In light of this, we examine the reliability and validity of frequently employed variants (and one new variant) of the numerical comparison task: two symbolic comparison variants and two nonsymbolic comparison variants. The results of two experiments demonstrate that measures of the NDE that use nonsymbolic stimuli are far more reliable than measures of the NDE that use symbolic stimuli. With respect to correlations between measures, we find evidence that the NDE that arises using symbolic stimuli is uncorrelated with the NDE that is elicited by using nonsymbolic stimuli. Results are discussed with respect to their implications for the use of the NDE as a metric of numerical processing and representation in research with both children and adults.     

Spatial attention as a necessary preliminary to early processes in reading.

One major theory of the relation between spatial attention and visual word recognition holds that the former is a necessary condition for the latter to begin. A different major theory asserts that although spatial attention can facilitate the latter, it is not a necessary condition. These two theories were pitted against each other experimentally. Spatial attention was operationalized in terms of the effect of a spatial precue on the time to name a target word that appeared above or below fixation. A masked prime word was presented before the target. The critical difference between experiments was cue validity (50% in Experiments 1a and 2a and 100% in Experiments 1b and 2b). Repetition priming was observed when the prime appeared in the uncued prime location in Experiments la and 2a but not in Experiments 1b or 2b. These results are inconsistent with the claim that visual word recognition does not depend on spatial attention. Discussion centres on the distribution of spatial attention across target locations as a function of cue validity.     

Toward a Metacognitive Account of Cognitive Offloading

Individuals frequently make use of the body and environment when engaged in a cognitive task. For example, individuals will often spontaneously physically rotate when faced with rotated objects, such as an array of words, to putatively offload the performance costs associated with stimulus rotation. We looked to further examine this idea by independently manipulating the costs associated with both word rotation and array frame rotation. Surprisingly, we found that individuals’ patterns of spontaneous physical rotations did not follow patterns of performance costs or benefits associated with being physically rotated, findings difficult to reconcile with existing theories of strategy selection involving external resources. Individuals’ subjective ratings of perceived benefits, rather, provided an excellent match to the patterns of physical rotations, suggesting that the critical variable when deciding on‐the‐fly whether to incorporate an external resource is the participant's metacognitive beliefs regarding expected performance or the effort required for each approach (i.e., internal vs. internal + external). Implications for metacognition's future in theories of cognitive offloading are discussed.