Interference across time: dissociating short from long temporal interference.

Our ability to identify an object is often impaired by the presence of preceding and/or succeeding task-irrelevant items. Understanding this temporal interference is critical for any theoretical account of interference across time and for minimizing its detrimental effects. Therefore, we used the same sequences of 3 orientation items, orientation estimation task, and computational models, to examine temporal interference over both short (<150 ms; visual masking) and long (175-475 ms; temporal crowding) intervals.

Temporal crowding with central vision reveals the fragility of visual representations.

This study examined whether temporal crowding-the impaired object identification when distracting objects precede and succeed it-occurs at the fovea and if so whether its magnitude is reduced. We presented a central sequence of three oriented items separated by relatively long intervals (200/400 ms) and used an orientation estimation task with mixture-model analyses. We found clear evidence of temporal crowding with central vision, even with 400 ms intervals.

Attention does not spread automatically along objects: Evidence from the pupillary light response.

Objects influence attention allocation; when a location within an object is cued, participants react faster to targets appearing in a different location within this object than on a different object. Despite consistent demonstrations of this object-based effect, there is no agreement regarding its underlying mechanisms. To test the most common hypothesis that attention spreads automatically along the cued object, we utilized a continuous, response-free measurement of attentional allocation that relies on the modulation of the pupillary light response.

Inter-individual variations in internal noise predict the effects of spatial attention.

Individuals differ considerably in the degree to which they benefit from attention allocation. Thus far, such individual differences were attributed to post-perceptual factors such as working-memory capacity. This study examined whether a perceptual factor - the level of internal noise - also contributes to this inter-individual variability in attentional effects.

Temporal crowding is a unique phenomenon reflecting impaired target encoding over large temporal intervals.

Crowding refers to impaired object identification when presented with other objects, and it is well established that spatial crowding-crowding from adjacent objects-affects many aspects of visual perception and cognition. A similar interference also occurs across time-the identification of a target object is impaired when distracting objects precede and succeed it. When such interference is observed with relatively long interitem intervals it is termed temporal crowding.

The effects of spatial attention on temporal integration measured with the ternus display.

While a large body of evidence has demonstrated the effects of attention on spatial processes, we know much less about attentional effects on the complementary temporal aspects of visual perception. To narrow this knowledge gap, we examined the effects of endogenous attention-the voluntary component of spatial attention-on temporal integration using the Ternus display. In a typical Ternus display, horizontally aligned discs shift by one position across alternating frames that are separated by a varying interframe interval.

The time-course of endogenous temporal attention - Super fast voluntary allocation of attention.

It is widely accepted that voluntary spatial attention is slow - it can only affect performance with medium and long cue-target intervals. Here, we examined whether this also holds for voluntary temporal attention. We performed a rigorous examination of the time-course of attention allocation to a point in time using two common paradigms for studying endogenous temporal attention: 'constant foreperiod' and 'temporal orienting'.

Can rhythm-induced attention improve the perceptual representation?

Temporal attention can be entrained exogenously to rhythms. Indeed, faster and more accurate responses were previously found when the target appeared in-phase with a preceding rhythm in comparison to when it was out of phase. However, the nature of this rhythm-induced attentional effect is not well understood.

Neural Variability Is Quenched by Attention.

Attention can be subdivided into several components, including alertness and spatial attention. It is believed that the behavioral benefits of attention, such as increased accuracy and faster reaction times, are generated by an increase in neural activity and a decrease in neural variability, which enhance the signal-to-noise ratio of task-relevant neural populations. However, empirical evidence regarding attention-related changes in neural variability in humans is extremely rare.

Relevance-based processing: Little role for task-relevant expectations.

This study examined the role of advance expectations in generating relevance-based selection, using a version of cognitive "blindness" that is driven solely by task relevance. With this irrelevance-induced blindness, participants often fail to report a feature of an irrelevant stimulus, even though the levels of perceptual and cognitive load are minimal (i.e.

The spatial distribution of attention.

Understanding how spatial attention is distributed over space (i.e. the attentional window) is highly important for theoretical, methodological, as well as applied reasons.

The size of the attentional window when measured by the pupillary response to light.

This study measured the size of the attentional window when attention is narrowly focused, using attentional modulation of the pupillary light response - pupillary constriction when covertly attending a brighter than darker area. This allowed us to avoid confounds and biases involved in relying on observers' response (e.g.

Sustained spatial attention can affect feature fusion.

When two verniers are presented in rapid succession at the same location, feature fusion occurs. Instead of perceiving two separate verniers, participants typically report perceiving one fused vernier, whose offset is a combination of the two previous verniers, with the later one slightly dominating. Here, we examined the effects of sustained attention-the voluntary component of spatial attention-on feature fusion.

The Joint Effects of Spatial Cueing and Transcranial Direct Current Stimulation on Visual Acuity.

The present study examined the mutual influence of cortical neuroenhancement and allocation of spatial attention on perception. Specifically, it explored the effects of transcranial Direct Current Stimulation (tDCS) on visual acuity measured with a Landolt gap task and attentional precues. The exogenous cues were used to draw attention either to the location of the target or away from it, generating significant performance benefits and costs.

Perceptual episodes, temporal attention, and the role of cognitive control: Lessons from the attentional blink.

The ability to identify a target is usually hindered if it appears shortly after another target. This simple and somewhat intuitive observation is qualified by a multitude of unexpected findings and conflicting theories that originate from the attentional blink paradigm. In this review, the major results, implications, and outstanding questions that stem from the paradigm are presented and discussed.

Attentional requirements in perceptual grouping depend on the processes involved in the organization.

Previous studies on the role of attention in perceptual grouping have yielded contradicting findings, some suggesting that grouping requires attention and others indicating that it does not. Kimchi and Razpurker-Apfeld (Psychonomic Bulletin and Review, 11(4), 687-696, 2004) showed that attentional demands in grouping could vary according to the processes involved. The current study expanded on this, examining whether attentional demands vary for (a) different grouping principles and (b) as a function of contingent processing of element segregation and shape formation.

Large inter-individual and intra-individual variability in the effect of perceptual load.

This study examined whether the recurrent difficulty to replicate results obtained with paradigms measuring distractor processing as a function of perceptual load is due to individual differences. We first reanalyzed, at the individual level, the data of eight previously reported experiments. These reanalyses revealed substantial inter-individual differences, with particularly low percentage of participants whose performance matched the load theory's predictions (i.

Spatial attention alleviates temporal crowding, but neither temporal nor spatial uncertainty are necessary for the emergence of temporal crowding.

Recently, we demonstrated temporal crowding with normal observers: Target identification was impaired when it was surrounded by other stimuli in time, even when the interstimuli intervals (ISIs) were relatively long. Here, we examined whether temporal and spatial uncertainties play a critical role in the emergence of temporal crowding. We presented a sequence of three letters to the same peripheral location, right or left of fixation, separated by varying ISI (106-459 ms).

The time course of the competition between grouping organizations.

Previous research on the competition between grouping organizations focused mainly on their relative strength as measured by subjective reports of the final percept. Considerably less is known about the underlying representations of the competing organizations. We hypothesized that when more than 1 organization is possible, multiple representations are constructed for the alternative organizations.

The typical advantage of object-based attention reflects reduced spatial cost.

In Egly, Driver, and Rafal's (1994) seminal study, an attentional precue appeared either at the target location (valid), a different location within the same object (invalid-same), or on another object (invalid-different). Performance was best in the valid condition, reflecting the advance allocation of spatial-attention. In addition, performance was better in the invalid-same than invalid-different condition, reflecting object-based attention allocation.

Perceptual organization, visual attention, and objecthood.

We have previously demonstrated that the mere organization of some elements in the visual field into an object attracts attention automatically. Here, we explored three different aspects of this automatic attentional capture: (a) Does the attentional capture by an object involve a spatial component? (b) Which Gestalt organization factors suffice for an object to capture attention? (c) Does the strength of organization affect the object's ability to capture attention? Participants viewed multi-elements displays and either identified the color of one element or responded to a Vernier target. On some trials, a subset of the elements grouped by Gestalt factors into an object that was irrelevant to the task and not predictive of the target.

Perceptual load in different regions of the visual scene and its relevance for driving.

Objective: The aim of this study was to better understand the role played by perceptual load, at both central and peripheral regions of the visual scene, in driving safety.

Background: Attention is a crucial factor in driving safety, and previous laboratory studies suggest that perceptual load is an important factor determining the efficiency of attentional selectivity. Yet, the effects of perceptual load on driving were never studied systematically.

Temporal crowding and its interplay with spatial crowding.

Spatial crowding refers to impaired target identification when the target is surrounded by other stimuli in space temporal crowding refers to impaired target identification when the target is surrounded by other stimuli in time previously, when spatial and temporal crowding were measured in the fovea they were interrelated with amblyopic observers but almost absent with normal observers bonneh, sagi, & polat, 2007. In the current study we examined whether reliable temporal crowding can be found for normal observers with peripheral presentation 9° of eccentricity, and whether similar relations between temporal and spatial crowding will emerge to that end, we presented a sequence of three displays separated by a varying interstimulus interval (ISI). Each display included either one letter : experiments 1a ,: 1b ,: 1c or three letters separated by a varying interletter spacing: Experiments 2a ,: 2b).

Seeing without knowing: task relevance dissociates between visual awareness and recognition.

We demonstrate that task relevance dissociates between visual awareness and knowledge activation to create a state of seeing without knowing-visual awareness of familiar stimuli without recognizing them. We rely on the fact that in order to experience a Kanizsa illusion, participants must be aware of its inducers. While people can indicate the orientation of the illusory rectangle with great ease (signifying that they have consciously experienced the illusion's inducers), almost 30% of them could not report the inducers' color.

Contrast dissimilarity effects on crowding are not simply another case of target saliency.

Previous studies have shown crowding alleviation when target and flankers similarity is reduced. However, in the case of contrast dissimilarity, the findings were inconsistent. This study examined the effect of stimulus contrast, particularly contrast dissimilarity, on both overall performance under crowded conditions and the critical distance-the spatial extent of crowding.