Preview Display Research Articles

The go no-go reviewing paradigm: A reliable method for measuring perceptual object-file updating.

The object-file framework explains how object continuity is maintained as objects move: it stipulates that when we focus our attention on an object, we automatically retrieve this object's recent history. Supporting evidence comes from the object-specific preview benefit (OSPB): participants are faster to name a target letter when the same letter appeared in the same versus a different object in a preceding (preview) display. Although this framework has been very influential, replicating the OSPB has proved difficult, presumably because observers could ignore the preview display. To address this problem, a modified object-reviewing paradigm was suggested, which became the standard paradigm: participants are required to report whether the target letter matches one of the preview display's letters. However, as this paradigm makes retrieval of the object's history task-relevant, it is a useful method for studying the structure of object representations for memory but does not capture the automaticity of the object-reviewing process, which is the heart of the object-file account of perception. Here, we suggest an alternative go/no-go object-reviewing paradigm that is specifically tailored to study object-files for perception: it requires participants to attend to the preview display, yet does not require explicit retrieval of the object history. Using our new paradigm, we reliably replicate the OSPB. As a proof of concept, we revisit the persistence of the OSPB, previously investigated with the modified paradigm.

Pilot behavior in preview tracking task

The influence of the input signal bandwidth and controlled element dynamics on the potential of the preview display for improving accuracy is considered. The pilot in the loop experiments in which the human operator tracked a program trajectory characterized by bandwidths of 0.2, 0.5, 1 rad/s were carried out with a number of simplified controlled element dynamics and with the predictive display/aircraft system dynamics. For the latter dynamics the experiments were performed for different preview times (from 0 up to 6 s) which allowed to define its optimal value.

Preview Display - The Mean of Decreasing Pilot Workload and Suppressing Nonlinear Effects in The Flight Control System

Abstract The results of two groups of experiments performed with preview and compensatory displays are discussed. In one of them the influence of the input signal bandwidth and controlled element dynamics on the potential of a preview display for decreasing the pilot workload and improving task performance were studied. The other group of experiments was dedicated to potential of preview display for suppression of pilot-induced oscillations in the case where the nonlinear effects (actuator’s rate limit) are considered in the controlled element dynamics. The last group of experiments was performed with input bandwidth ωi = 0.5 rad/s.

Effects of Preview on Human Control Behavior in Tracking Tasks With Various Controlled Elements.

This paper investigates how humans use a previewed target trajectory for control in tracking tasks with various controlled element dynamics. The human's hypothesized "near" and "far" control mechanisms are first analyzed offline in simulations with a quasi-linear model. Second, human control behavior is quantified by fitting the same model to measurements from a human-in-the-loop experiment, where subjects tracked identical target trajectories with a pursuit and a preview display, each with gain, single-, and double-integrator controlled element dynamics. Results show that target-tracking performance improves with preview, primarily due to the far-viewpoint response, which allows humans to cancel their own and the controlled element's lags, without additional control activity. The near-viewpoint response yields better target tracking at higher frequencies, but requires substantially more control activity. The control-theoretic approach adopted in this paper provides unique quantitative insights into human use of preview, which can help to explain human behavior observed in other preview control tasks, like driving.

Proactive and Reactive Processes in the Medial Frontal Cortex: An Electrophysiological Study

The posterior medial frontal cortex (pMFC) is known to be involved in adaptive goal-directed behavior, but its specific function is not yet clear. Most theories have proposed that the pMFC monitors performance in a reactive manner only, but it is possible that the pMFC also contributes to performance monitoring in a proactive manner. To date, the evidence for proactive pMFC activity is equivocal. Here, we investigated pMFC activity before, during and after the performance of a challenging motor task. Participants navigated a cursor through narrow and wide mazes in randomly intermixed trials. On each trial, participants saw previews of the actual maze display prior to gaining control of the cursor. Event-related potentials (ERPs) to the preview displays were compared to ERPs elicited by no-go signals and errors. Compared to the wider maze, the preview display for the more challenging narrow maze elicited a medial-frontal negativity (MFN) similar to the ERP components elicited by no-go signals and errors. Like these known ERP components, the preview-elicited MFN appeared to be generated from a source in pMFC. This is consistent with the hypothesis that the pMFC participates in adaptive behavior whenever there is a need for increased effort to maintain successful task performance.

A functional role for trans-saccadic luminance differences

In typical natural environments, the visual system receives different inputs in quick succession as gaze moves around. We examined whether local trans-saccadic differences in luminance, contrast, and orientation influenced perception and target selection in the eye movement system. Observers initially fixated a peripheral position in a preview display that consisted of four patterns. They subsequently made a saccade to the center of the configuration. During the movement, two of the preview patterns were eliminated, and a small change in the luminance contrast of the remaining patterns was introduced. Observers had to make a second saccade to the test patch with the greater luminance contrast relative to the background. During the second fixation, test patterns could be in the same retinotopic location as one of the preview patterns during the initial fixation (a retinotopic match) or at a retinotopic location that was empty during the preview epoch (a retinotopic onset). We consistently found a preference to fixate retinotopic onsets over retinotopically matched patterns, but only when the patterns were defined by a luminance difference. Direct measurement of perceived luminance showed that the visual response to retinotopically matched inputs was attenuated, possibly because of retinotopic adaptation. As a consequence, the visual system responds more strongly to trans-saccadic differences in local luminance. We argue that a trans-saccadic comparison of the local luminance at the same retinotopic location is a simple way of finding high spatial frequency edge information in the visual scene. This information is important for image segmentation and interpretation.

Comparing Segmentation by Time and by Motion in Visual Search: An fMRI Investigation

Brain activity was recorded while participants engaged in a difficult visual search task for a target defined by the spatial configuration of its component elements. The search displays were segmented by time (a preview then a search display), by motion, or were unsegmented. A preparatory network showed activity to the preview display, in the time but not in the motion segmentation condition. A region of the precuneus showed (i) higher activation when displays were segmented by time or by motion, and (ii) correlated activity with larger segmentation benefits behaviorally, regardless of the cue. Additionally, the results revealed that success in temporal segmentation was correlated with reduced activation in early visual areas, including V1. The results depict partially overlapping brain networks for segmentation in search by time and motion, with both cue-independent and cue-specific mechanisms.

Perceptual Grouping of Object Contours Survives Saccades

Human observers explore scenes by shifting their gaze from object to object. Before each eye movement, a peripheral glimpse of the next object to be fixated has however already been caught. Here we investigate whether the perceptual organization extracted from such a preview could guide the perceptual analysis of the same object during the next fixation. We observed that participants were indeed significantly faster at grouping together spatially separate elements into an object contour, when the same contour elements had also been grouped together in the peripheral preview display. Importantly, this facilitation occurred despite a change in the grouping cue defining the object contour (similarity versus collinearity). We conclude that an intermediate-level description of object shape persists in the visual system across gaze shifts, providing it with a robust basis for balancing efficiency and continuity during scene exploration.

Episodic representation of diagnostic and nondiagnostic object colour

In three experiments, we investigated transsaccadic object file representations. In each experiment, participants moved their eyes from a central fixation cross to a saccade target located between two peripheral objects. During the saccade, this preview display was replaced with a target display containing a single object to be named. On trials in which the target identity matched one of the preview objects, its colour either matched or did not match the previewed object colour. The results indicated that colour changes disrupt perceptual continuity, but only for the class of objects for which colour is diagnostic of object identity. When the colour is not integral to identifying an object (for example, when the object is a letter or an object without a characteristic colour), object continuity is preserved regardless of changes to the object's colour. These results suggest that object features that are important for defining the object are incorporated into its episodic representation. Furthermore, the results are consistent with previous work showing that the quality of a feature's representation determines its importance in preserving continuity.

Episodic representations of object color

We investigated the episodic representation of object color, within a transsaccadic preview paradigm. While fixated on a central cross, participants viewed a preview display consisting of two objects located above and below a peripheral cross. Participants initiated a saccade to the peripheral cross immediately upon the appearance of the preview display. During the saccade, the preview display was replaced by a target display, consisting of a single familiar object in one of the previewed locations; the participant's task was to name the object as quickly as possible after the eyes landed. Half of the trials required the additional task of identifying whether the target object's color matched its color in the preview display. The results revealed an object-specific priming effect: that is, participants named the object more quickly when it appeared in its previewed location than when it appeared in the opposite location. On trials in which participants did not perform the secondary task, changing the object color reduced the size of the effect. However, when the secondary task was included object specific priming was unaffected by a change in target color. The results suggest that task requirements play a role in determining which features are critical to preserving object continuity.

Attentional capture by unique temporal change

The time course of attentional capture was measured in the preview search paradigm (Yantis & Joinides, 1984). Participants were first presented a circular preview display of figure eights. After one second two to four line segments of each figure eight were deleted to reveal a search display of letters, with two letters arbitrarily designated as targets. The participant's task was to press one of two keys as rapidly as possible to report target identity. Attentional capture was indexed by the relative ratio of RT slopes, taken over the display size, for targets that appear in unchanged versus unique display item locations. This is based on the assumption that when a unique item draws attention to itself, it will slow search if it happens to be one of the distractor letters. The current study points to a temporal factor, over and above the importance of new objects and relative signal speed, which is critical for attentional capture. Attention is captured by temporally unique events. The results of three experiments show that feature changes capture attention as effectively as new objects provided they occur during a period in which the display is static. Conversely, these same feature changes do not capture attention when they occur simultaneously with other display changes, such as the sudden onset of all items or the deletion of some line segments in all items. Importantly, the results show that this unique event hypothesis applies to changes in color (Experiment 1), in motion (Experiment 2) and even to the sudden appearance of new objects (Experiment 3). These findings highlight the importance of considering both space and time in studies of attentional capture.

Visual search at isoluminance: Evidence for enhanced color weighting in standard sub-set and preview-based visual search

Isoluminant displays depend on responses from the parvocellular visual stream, known to code color information. We examined the influence of isoluminance on attentional guidance by color using two procedures: (i) color sub-set search ( Egeth, Virzi, & Garbart, 1984) and (ii) preview search ( Watson & Humphreys, 1997). We used displays that do not generate a sub-set search advantage with luminant stimuli. Despite this, a sub-set search advantage was present for small color groups with isoluminant displays. Under preview-search conditions, presenting items at isoluminance amplified the effects of a negative color carry-over from a preview display to a new target, but only when there was an extended preview duration. Both findings demonstrate that presenting items at isoluminance increases the influence of color on visual search. Collectively, the data are consistent with the notion of a flexible inhibitory mechanism that can change the weighting applied to visual features in search.

How object-specific are object files? Evidence for integration by location.

Given the distributed representation of visual features in the human brain, binding mechanisms are necessary to integrate visual information about the same perceptual event. It has been assumed that feature codes are bound into object files--pointers to the neural codes of the features of a given event. The present study investigated the perceptual criteria underlying integration into an object file. Previous studies confounded the sharing of spatial location with belongingness to the same perceptual object, 2 factors we tried to disentangle. Our findings suggest that orientation and color features appearing in a task-irrelevant preview display were integrated irrespective of whether they appeared as part of the same object or of different objects (e.g., 1 stationary and the other moving continuously, or a banana in a particular orientation overlaying an apple of a particular color). In contrast, integration was markedly reduced when the 2 objects were separated in space. Taken together, these findings suggest that spatial overlap of visual features is a sufficient criterion for integrating them into the same object file.

Measuring the spread of spreading suppression: A time-course analysis of spreading suppression and its impact on attentional selection

We report three experiments investigating the time course of spreading suppression in visual search using preview conditions. A novel color-change procedure was employed in which a target letter changed into a new (singleton) color at various intervals after the onset of the search display. Performance when the singleton was unique across both preview and search displays was compared with that when the singleton carried the color of the preview display. Relative to the unique singleton baseline there were no costs to targets carrying the preview color when the singleton onset occurred shortly (80 ms) after the onset of the new, search display; however, costs emerged as the SOA increased before subsequently decreasing again. In addition, relative to when all the items appeared together (the full-set search baseline), there were benefits when the singleton replaced a target carrying the same color as the distractors in a search display, with the facilitation effect showing a marginal effect at an earlier time than the cost found when the change was to the preview color. The data suggest that there are contrasting time courses to attentional guidance to targets and the suppressive rejection of distractors in visual search.

Object continuity and the transsaccadic representation of form

Transsaccadic object file representations were investigated in three experiments. Subjects moved their eyes from a central fixation cross to a location between two peripheral objects. During the saccade, this preview display was replaced with a target display containing a single object to be named. On trials on which the target identity matched one of the preview objects, its orientation either matched or did not match the previewed orientation. The results of Experiments 1 and 2 revealed that orientation changes disrupt perceptual continuity for objects located near fixation, but not for objects located further from fixation. The results of Experiment 3 confirmed that orientation changes do not disrupt continuity for distant objects, while showing that subjects nevertheless maintain an object-specific representation of the orientation of such objects. Together, the results suggest that object files represent orientation but that whether or not orientation plays a role in the processes that determine continuity depends on the quality of the perceptual representation.

Fast color grouping and slow color inhibition: Evidence for distinct temporal windows for separate processes in preview search.

The authors report 4 experiments that examined color grouping and negative carryover effects in preview search via a probe detection task (J. J. Braithwaite, G. W. Humphreys, & J. Hodsoll, 2003). In Experiment 1, there was evidence of a negative color carryover from the preview to new items, using both search and probe detection measures. There was also a negative bias against probes on old items that carried the majority color in the preview. With a short preview duration (150 ms) carryover effects to new items were greatly reduced, but probe detection remained biased against the majority color in the old items. Experiments 2 and 4 showed that the color bias effects on old items could be reduced when these items had to be prioritized relative to being ignored. Experiment 3 tested and rejected the idea that variations in the probability of whether minority or majority colors were probed were crucial. These results show that the time course of color carryover effects can be separated from effects of early color grouping in the preview display: Color grouping is fast, and inhibitory color carryover effects are slow.

Location-based selection for storage in visuo-spatial working memory

Visual working memory is characterised by a limited storage capacity. Given this storage limitation, selection of behaviourally relevant objects based on locations, features or object category, is crucial. We conducted behavioural and ERP experiments to investigate location-based selection of multiple targets for storage in visual working memory, with a change detection paradigm. In the first experiment, the spatial locations of target-objects were marked in a preview display, before the appearance of target and distracter objects in the memory display. In the second experiment, spatial locations of distracter (response-irrelevant) objects were marked in the preview display. In the third experiment, a delay was introduced between preview and memory displays. In the forth experiment, the role of configuration-invariance in the transition between two subsequent preview displays, was investigated. The results show the effectiveness of the filtering is limited to two or three target objects, respectively. In addition, the filtering effect can be partly explained by selection of a global spatial configuration of location pre-cues, which is superimposed to the selection of individual object locations. In the fifth experiment, the neural processes of spatial marking of target locations were investigated by means of an ERP study. The results of this experiment show that filtering of target objects takes place both during encoding and maintenance of the memory display. The effect during maintenance was larger over the first half second of the maintenance interval. This time specificity suggests an attentional consolidation effect during the delayed activity of the neurons. Finally, we developed a neurocomputational model to account for the behavioural and ERP results.

Does Previewing One Stimulus Feature Help Conjunction Search?

We examined the effects of previewing one aspect of a search display, in order to determine what subset of display information is most useful as a prelude to a search task. Observers were asked to indicate the presence or absence of a known target, in a conjunction search where the target was defined by the combination of colour and orientation (a yellow horizontal line presented among yellow vertical and pink horizontal distractors). In the colour preview condition of experiment 1, observers were first shown a 1 s preview of the locations and colours of the search items before the actual search set was presented. That is, search items first appeared as yellow and pink squares for 1 s, which each then turned into yellow and pink oriented lines (in the same locations) which comprised the display to be searched. In the orientation preview condition, observers were first shown a 1 s preview of the locations and orientations of the search items before the actual search display was presented. These two conditions were compared to a control condition consisting of standard conjunction search without any preview display. There was no effect of colour preview; there was a marginal effect of orientation preview, but in the opposite direction from what was expected reaction time increased for orientation preview searches. In experiment 2 these previews were compared to two spatial cueing conditions; in this experiment the colour preview did provide a small amount of help. Finally, in experiment 3 both previews were presented in succession, and increased facilitation was found, in particular when the colour preview preceded the orientation preview. These findings are discussed in relation to the literature, in particular the Guided Search model (Wolfe et al 1989 Journal of Experimental Psychology: Human Perception and Performance 15 419-433; Wolfe 1994 Psychonomic Bulletin & Review 1 202-238).

Types and tokens in transsaccadic object identification: effects of spatial position and left-right orientation.

What types of representations support our ability to integrate information acquired during one eye fixation with information acquired during the next fixation? In Experiment 1, transsaccadic integration was explored by manipulating whether or not the relative position of a picture of an object was maintained across a saccade. In Experiment 2, the degree to which visual details of a picture are coded in a position-specific representational system was explored by manipulating whether or not both the relative position and the left-right orientation of the picture were maintained across a saccade. Position-specific and nonspecific preview benefits were observed in both experiments. Only the position-specific benefits were influenced by the number of task-relevant pictures presented in the preview display (Experiment 1) and the left-right orientation of the picture presented in the preview display (Experiment 2). The results support a model of transsaccadic integration based on two independent representational systems. One system codes abstract, prestored object types, and the other codes episodic tokens consisting of stimulus properties linked to scene- or configuration-based position markers.

Dynamic Auditory Preview for Visually Guided Target Aiming

The effects of a dynamic auditory preview display were examined in a visual target aiming task. A moving sound stimulus aligned with a visual target was presented over various distances beyond the bounds of a visual display. Results indicated reduced error magnitudes in aimed responses to visual targets with increasing auditory preview distance. In subsequent testing, the effects of position and velocity misalignments between the sound source and the visual target were assessed. In position misalignment conditions where the sound source lagged behind the visual target, higher error magnitudes were observed. However, when the auditory display preceded the visual target, performance improved. In velocity mismatch conditions, responses toward fast moving targets improved when a relatively faster sound source was previewed but were disrupted when a slower sound source was previewed. On the contrary, responses toward slow moving targets improved when a relatively slower sound source was previewed and were disrupted when a faster sound source was previewed.