Change detection on a hunch: pre-attentive vision allows "sensing" of unique feature changes

Expert and Novice Goalkeepers' Perceptions of Changes During Open Play Soccer

In the present study we investigated expert and novice football (i.e., soccer) goalkeepers' three stages of perceiving changes in open play situations-detection, localization, and identification-with and without time constraints. We adopted the continual cycling flicker paradigm to investigate goalkeepers' perceptions when provided with sufficient time (Experiment 1), and we utilized the limited display one-shot change detection paradigm to study their perceptions under time constraints (Experiment 2). Images of goalkeepers' first-person views of open play soccer scenes were used as stimuli. Semantic or non-semantic changes in these scenes were produced by modifying one element in each image. Separate groups of expert and novice goalkeepers were required to detect, localize, and identify the scene changes. We found that expert goalkeepers detected scene changes more quickly than novices under both time allowances. Furthermore, compared to novices, experts localized the changes more accurately under time constraints and identified the changes more quickly when given sufficient time. Additionally, semantic changes were detected more quickly and localized and identified more accurately than non-semantic changes when there was sufficient time. Under time constraints expert goalkeepers' greater efficiency was likely due to pre-attentive processing; with sufficient time, they were able to focus attention to extracting detailed information for identification.

Sensing and seeing associated with overlapping occipitoparietal activation in simultaneous EEG-fMRI

The presence of a change in a visual scene can influence brain activity and behavior, even in the absence of full conscious report. It may be possible for us to sense that such a change has occurred, even if we cannot specify exactly where or what it was. Despite existing evidence from electroencephalogram (EEG) and eye-tracking data, it is still unclear how this partial level of awareness relates to functional magnetic resonance imaging (fMRI) blood oxygen level dependent (BOLD) activation. Using EEG, fMRI, and a change blindness paradigm, we found multi-modal evidence to suggest that sensing a change is distinguishable from being blind to it. Specifically, trials during which participants could detect the presence of a colour change but not identify the location of the change (sense trials), were compared to those where participants could both detect and localise the change (localise or see trials), as well as change blind trials. In EEG, late parietal positivity and N2 amplitudes were larger for localised changes only, when compared to change blindness. However, ERP-informed fMRI analysis found no voxels with activation that significantly co-varied with fluctuations in single-trial late positivity amplitudes. In fMRI, a range of visual (BA17,18), parietal (BA7,40), and mid-brain (anterior cingulate, BA24) areas showed increased fMRI BOLD activation when a change was sensed, compared to change blindness. These visual and parietal areas are commonly implicated as the storage sites of visual working memory, and we therefore argue that sensing may not be explained by a lack of stored representation of the visual display. Both seeing and sensing a change were associated with an overlapping occipitoparietal network of activation when compared to blind trials, suggesting that the quality of the visual representation, rather than the lack of one, may result in partial awareness during the change blindness paradigm.

Is It Implicit Detection or Perception During Change Blindness?

Purpose

Implicit detection differs from implicit perception. The former includes implicit registration, localisation, identification and comparison of an object. Implicit comparison is not necessary for implicit perception, and should not involve the identification or localisation of objects. While many studies have reported evidence of implicit detection in change blindness, they may, in fact, have only observed implicit perception. In this study, we aimed to find out whether there is implicit detection or perception during the change blindness period.

Methods

In Experiments 1 and 2, we used a simple change detection paradigm, coupled with a speeded attribute discrimination task. Reaction times (RTs) and accuracy of the participants were measured for the speeded attribute discrimination task. We compared differences in RT and accuracy of the invalid and congruent cue trials to find evidence for implicit detection. Invalid trials referred to stimuli where the appearance of the cue does not change, whereas congruent trials involved cued objects with the same attributes as that of the change object. In Experiment 3, a one-shot change detection experiment was conducted, where subjects were required to report whether the objects were the same or different as quickly as possible. We compared the differences in RTs between trials in which the stimulus exhibited a change but participants reported “same” (change blindness trails) and trials in which the stimulus exhibited no change and participants reported “same” (baseline trials), to find evidence for implicit perception.

Results

In Experiments 1 and 2, the difference in accuracy and RTs under invalid and congruent conditions was not significant. We did not observe a validity effect as evidence for implicit localisation or a congruency effect as evidence for identification. In Experiment 3, the RTs were longer in the change blindness relative no-change trials, which indicated that there was implicit perception.

Conclusion

The results of this study showed that there was no evidence supporting implicit detection in colour or orientation as a single or a combination of features. However, we report evidence for implicit perception during the change blindness period. Change may be implicitly perceived, but not located or identified before there is conscious detection.

An EEG study of detection without localisation in change blindness

Previous studies of change blindness have suggested a distinction between detection and localisation of changes in a visual scene. Using a simple paradigm with an array of coloured squares, the present study aimed to further investigate differences in event-related potentials (ERPs) between trials in which participants could detect the presence of a colour change but not identify the location of the change (sense trials), versus those where participants could both detect and localise the change (localise trials). Individual differences in performance were controlled for by adjusting the difficulty of the task in real time. Behaviourally, reaction times for sense, blind, and false alarm trials were distinguishable when comparing across levels of participant certainty. In the EEG data, we found no significant differences in the visual awareness negativity ERP, contrary to previous findings. In the N2pc range, both awareness conditions (localise and sense) were significantly different to trials with no change detection (blind trials), suggesting that this ERP is not dependent on explicit awareness. Within the late positivity range, all conditions were significantly different. These results suggest that changes can be ‘sensed’ without knowledge of the location of the changing object, and that participant certainty scores can provide valuable information about the perception of changes in change blindness.

Two good reasons to say 'change!' - ensemble representations as well as item representations impact standard measures of VWM capacity

Visual working memory (VWM) is a central bottleneck in human information processing. Its capacity is most often measured in terms of how many individual-item representations VWM can hold (k). In the standard task employed to estimate k, an array of highly discriminable colour patches is maintained and, after a short retention interval, compared to a test display (change detection). Recent research has shown that with more complex, structured displays, change-detection performance is, in addition to individual-item representations, supported by ensemble representations formed as a result of spatial subgroupings. Here, by asking participants to additionally localize the change, we reveal indication for an influence of ensemble representations even in the very simple, unstructured displays of the colour-patch change-detection task. Critically, pure-item models from which standard formulae of k are derived do not consider ensemble representations and, therefore, potentially overestimate k. To gauge this overestimation, we develop an item-plus-ensemble model of change detection and change localization. Estimates of k from this new model are about 1 item (~30%) lower than the estimates from traditional pure-item models, even if derived from the same data sets.

The Flash-Lag, Fröhlich and Related Motion Illusions Are Natural Consequences of Discrete Sampling in the Visual System

The Fröhlich effect and flash-lag effect, in which moving objects appear advanced along their trajectories compared to their actual positions, have defied a simple and consistent explanation. Here, I show that these illusions can be understood as a natural consequence of temporal compression in the human visual system. Discrete sampling at some stage of sensory perception has long been considered, and if it were true, it would necessarily lead to these illusions of motion. I show that the discrete perception hypothesis, with a single free parameter, the perceptual moment or sampling rate, can quantitatively explain all of the scenarios of the Fröhlich and flash-lag effect. I interpret discrete perception as the implementation of data compression in the brain, and our conscious perception as the reconstruction of the compressed input.

Phasic and sustained interactions of multisensory interplay and temporal expectation

Every moment organisms are confronted with complex streams of information which they use to generate a reliable mental model of the world. There is converging evidence for several optimization mechanisms instrumental in integrating (or segregating) incoming information; among them are multisensory interplay (MSI) and temporal expectation (TE). Both mechanisms can account for enhanced perceptual sensitivity and are well studied in isolation; how these two mechanisms interact is currently less well-known. Here, we tested in a series of four psychophysical experiments for TE effects in uni- and multisensory contexts with different levels of modality-related and spatial uncertainty. We found that TE enhanced perceptual sensitivity for the multisensory relative to the best unisensory condition (i.e. multisensory facilitation according to the max-criterion). In the latter TE effects even vanished if stimulus-related spatial uncertainty was increased. Accordingly, computational modelling indicated that TE, modality-related and spatial uncertainty predict multisensory facilitation. Finally, the analysis of stimulus history revealed that matching expectation at trial n-1 selectively improves multisensory performance irrespective of stimulus-related uncertainty. Together, our results indicate that benefits of multisensory stimulation are enhanced by TE especially in noisy environments, which allows for more robust information extraction to boost performance on both short and sustained time ranges.

To Have Seen or Not to Have Seen: A Look at Rensink, O'Regan, and Clark (1997)

Rensink, O'Regan, and Clark drew attention to the phenomenon of change blindness, in which even large changes can be difficult to notice if made during the appearance of motion transients elsewhere in the image. This article provides a sketch of the events that inspired that article as well as its subsequent impact on psychological science and on society at large.

The role of multisensory interplay in enabling temporal expectations

Temporal regularities can guide our attention to focus on a particular moment in time and to be especially vigilant just then. Previous research provided evidence for the influence of temporal expectation on perceptual processing in unisensory auditory, visual, and tactile contexts. However, in real life we are often exposed to a complex and continuous stream of multisensory events. Here we tested - in a series of experiments - whether temporal expectations can enhance perception in multisensory contexts and whether this enhancement differs from enhancements in unisensory contexts. Our discrimination paradigm contained near-threshold targets (subject-specific 75% discrimination accuracy) embedded in a sequence of distractors. The likelihood of target occurrence (early or late) was manipulated block-wise. Furthermore, we tested whether spatial and modality-specific target uncertainty (i.e. predictable vs. unpredictable target position or modality) would affect temporal expectation (TE) measured with perceptual sensitivity (d^') and response times (RT). In all our experiments, hidden temporal regularities improved performance for expected multisensory targets. Moreover, multisensory performance was unaffected by spatial and modality-specific uncertainty, whereas unisensory TE effects on d^' but not RT were modulated by spatial and modality-specific uncertainty. Additionally, the size of the temporal expectation effect, i.e. the increase in perceptual sensitivity and decrease of RT, scaled linearly with the likelihood of expected targets. Finally, temporal expectation effects were unaffected by varying target position within the stream. Together, our results strongly suggest that participants quickly adapt to novel temporal contexts, that they benefit from multisensory (relative to unisensory) stimulation and that multisensory benefits are maximal if the stimulus-driven uncertainty is highest. We propose that enhanced informational content (i.e. multisensory stimulation) enables the robust extraction of temporal regularities which in turn boost (uni-)sensory representations.