Spatial negative priming modulation: The influence of probe-trial target cueing,distractor presence,and an intervening response

Reaction times are slower when a target (T) appears at a location that has just contained a distractor (D) (ignored-repetition trial), relative to when it arises at a previously unoccupied spatial position (control trial), i.e., the spatial negative priming (NP) effect. In a typical spatial NP paradigm trials are presented in pairs, first the prime and then the probe. Validly cueing ignored-repetition trials, and/or reducing probe distractor probability, modulated the NP process under certain conditions following target-plus-distractor (prime response) but not after distractor-only (no prime response) primes. This supported the idea that the production of a prime (intervening) response meets the needs for producing NP modulation. Additionally, NP elimination, evident when the probe was randomly distractor-free, was not seen when the probe also contained a distractor event. This suggests that the removal of the NP effect is likely achieved by blocking the retrieval of prime distractor information, rather than by removing the NP cause. Seemingly, the presence of a probe distractor is able to bypass the retrieval block.     

Where has all the inhibition gone? Insights from electrophysiological measures into negative priming without probe distractors

Responses to probe targets that have been distractors in a prime display are slower than responses to unrepeated stimuli, a finding labeled negative priming (NP). However, without probe distractors the NP effect usually diminishes. The present study is the first to investigate ERP correlates of NP without probe distractors to shed light on the processes underlying NP. Based on existing findings in the field, we analyzed two ERP correlates that have been associated with the visual NP effect so far, namely the N200 and the P300. As expected, no behavioral NP effect as well as no N200 modulation emerged. However, the P300 component was enhanced when a prime distractor was repeated as the probe target. This effect is interpreted as reflecting automatic retrieval of the prime episode occurring independently of the presence of probe distractors.     

Can the location negative priming process operate in a proactive manner?

The location negative priming (NP) effect refers to the fact that the processing of a current target stimulus (probe trial) is delayed when it appears at a location that has recently contained a distractor event (prime trial), relative to when it occurs at a previously unoccupied position. One view is that the process causing the NP effect involves the inhibition of the internal representation of the prime-distractor event, and that the future processing of target stimuli that involve this event are prolonged because this distractor inhibition is persistent. In this study, we examined the possibility that the NP process (inhibition) could act proactively; specifically asking whether inhibition could be allocated to a location merely predicted to hold a future distractor event. To do this, we cued the probe distractor's location using an otherwise traditional location NP paradigm. No evidence of a proactive NP process was obtained. Probe-trial target latency was the same whether it appeared at the cued distractor location or at a new location, but was delayed when it occupied the prime-distractor location (NP effect). The location NP process is seemingly a reactive one, applying inhibition only when an actual distractor is present, much as past theories have implied.     

Target localization among concurrent sound sources: No evidence for the inhibition of previous distractor responses

The visuospatial negative priming effect—that is, the slowed-down responding to a previously ignored location—is partly due to response inhibition associated with the previously ignored location (Buckolz, Goldfarb, & Khan, Perception & Psychophysics 66:837-845 2004). We tested whether response inhibition underlies spatial negative priming in the auditory modality as well. Eighty participants localized a target sound while ignoring a simultaneous distractor sound at another location. Eight possible sound locations were arranged in a semicircle around the participant. Pairs of adjacent locations were associated with the same response. On ignored repetition trials, the probe target sound was played from the same location as the previously ignored prime sound. On response control trials, prime distractor and probe target were played from different locations but were associated with the same response. On control trials, prime distractor and probe target shared neither location nor response. A response inhibition account predicts slowed-down responding when the response associated with the prime distractor has to be executed in the probe. There was no evidence of response inhibition in audition. Instead, the negative priming effect depended on whether the sound at the repeatedly occupied location changed identity between prime and probe. The latter result replicates earlier findings and supports the feature mismatching hypothesis, while the former is compatible with the assumption that response inhibition is irrelevant in auditory spatial attention.     

Disengagement of the location negative priming effect: The influence of an intervening response

Reaction time is significantly longer when a target stimulus arises at a location that has just contained a distractor event, relative to when it appears at a new location [i.e., called, the location negative priming (NP) effect]. The NP effect is eliminated when the second of two paired trials (i.e., prime-to-probe trials) predictably lacks a distractor when the preceding trial contains both a target and a distractor event (T+D), but not when a prime distractor appears alone (D-only). We tested the possibility that the failed NP process disengagement seen with D-only prime trials resulted because they do not require the production of an overt intervening response. This possibility was supported. Results also showed that the intervening response had to meet prerequisites; namely, the response had to be prime-generated, i.e., come from the subset of experimental responses and have engaged in a conflict with the prime distractor-activated response.     

The influence of distractor-only prime trials on the location negative priming mechanism

Two experiments were conducted that examined the influence of distractor-only prime trials on the "location" negative priming (NP) effect. In all experiments, the probe trial always lacked a distractor. We showed that the predictable absence of a probe distractor caused the elimination of the location NP effect when the prime trial contained both a target and a distractor event (T + D-->T), but not when the prime contained only a to-be-ignored distractor event (D-->T) (Milliken, Tipper, Houghton, & Lupianez, 2000). The preservation of the NP effect seen with the distractor-only prime trials (D-->T) was not the result of its lacking a prime-trial selection, nor was it the consequence of its representing a higher level of episodic similarity than the T + D-->T condition. Finally, the location NP effect observed for the D-->T condition is seemingly consistent with the view that location NP and the inhibition-of-return effects share a common underlying process (Milliken et al., 2000).     

The adaptive character of the attentional system: statistical sensitivity in a target localization task

A localization task required participants to indicate which of 4 locations contained a briefly displayed target. Most displays also contained a distractor that was not equally probable in these locations, affecting performance dramatically. Responses were faster when a display had no distractor and almost as fast when the distractor was in its frequent location. Conversely, responses were slower when targets appeared in frequent-distractor locations, even thou targets were equally likely in each location. Negative-priming effects were reliably smaller when targets followed distractors in the frequent-distractor location compared to the rare-distractor location, challenging the episodic-retrieval account Experiment 2 added a 5th location that rarely displayed distractors and never targets, yet responses slowed most when distractors appeared there. The results confirmed that the attentional system is sensitive to first- and higher-order statistical patterns and can make short- and long-term adjustments in preferences based on prior history of inspecting unsuccessful locations.     

The Effects of Cueing Target Location and Response Mode on Interference and Negative Priming Using a Visual Selection Paradigm

Two experiments are reported that examine the effects of cueing the location of a target in the prime display on interference and subsequent negative priming. The prime and probe displays comprised two words, a target and a distractor. In the prime display, the two words were either the same (response compatible) or different (response incompatible). The target in the probe display was unrelated to the prime distractor (control), the same word as the distractor (ignored repetition), or semantically related to the distractor (ignored semantic repetition). In Experiment 1, cueing the location of the prime target significantly reduced the interference effect but not the subsequent identity negative priming (NP) effect. In contrast, not cueing the prime target resulted in the elimination of the identity NP. There was no evidence of semantic NP in this experiment. In Experiment 2, where a categorization response was required, significant interference was obtained in the prime display that was not influenced by cueing the location of the target. Although there was significant semantic NP, identity NP failed to reach significance. The two experiments were analysed together, and findings are discussed in relation to current models of negative priming.     

The error protection impact of inhibitory after-effects in a location-based task and its preservation with practice

In location-based tasks, responses related to (prime trial) distractor-occupied locations automatically undergo activation, followed by inhibition, which causes these responses to become execution-resistant (ER). Distractor-response ER takes time to override, delaying target reactions that later require this response (e.g., probe, ignored-repetition trials), causing the spatial negative priming (SNP) phenomenon. We learned in this study that distractor-response ER affords this output a degree of error protection. Specifically, when the probe target appeared at a new location, former (prime) distractor responses were used erroneously significantly less often than their control response counterparts, likely due to their ER feature, which discourages their inappropriate selection (i.e., “ER” provides error protection). This error protection also was evident when a previous distractor response was activated by a distractor on the probe (i.e., distractor-repeat trial). Notably, error protection remained effective over extensive practice, as did SNP size (i.e., ER override time) after an initial decline.     

Top-down and bottom-up attentional control: On the nature of interference from a salient distractor

In two experiments using spatial probes, we measured the temporal and spatial interactions between top-down control of attention and bottom-up interference from a salient distractor in visual search. The subjects searched for a square among circles, ignoring color. Probe response times showed that a color singleton distractor could draw attention to its location in the early stage of visual processing (before a 100-msec stimulus onset asynchrony [SOA]), but only when the color singleton distractor was located far from the target. Apparently the bottom-up activation of the singleton distractor’s location is affected early on by local interactions with nearby stimulus locations. Moreover, probe results showed that a singleton distractor did not receive attention after extended practice. These results suggest that top-down control of attention is possible at an early stage of visual processing. In the long-SOA condition (150-msec SOA), spatial attention selected the target location over distractor locations, and this tendency occurred with or without extended practice.     

More capture,more suppression: Distractor suppression due to statistical regularities is determined by the magnitude of attentional capture

Salient yet irrelevant objects often interfere with daily tasks by capturing attention against our best interests and intentions. Recent research has shown that through implicit learning, distraction by a salient object can be reduced by suppressing the location where this distractor is likely to appear. Here, we investigated whether suppression of such high-probability distractor locations is an all-or-none phenomenon or specifically tuned to the degree of interference caused by the distractor. In two experiments, we varied the salience of two task-irrelevant singleton distractors each of which was more likely to appear in one specific location in the visual field. We show that the magnitude of interference by a distractor determines the magnitude of suppression for its high-probability location: The more salient a distractor, the more it becomes suppressed when appearing in its high-probability location. We conclude that distractor suppression emerges as a consequence of the spatial regularities regarding the location of a distractor as well as its potency to interfere with attentional selection.

     

Effects of prime—target spatial separation and attentional deployment on masked repetition priming

In two masked repetition priming experiments with letter stimuli, the positions of prime and target stimuli were varied horizontally from fixation. Priming effects did not interact with position when prime and target location covaried (Experiment 1A) but diminished with increasing prime eccentricity when targets were always centrally located (Experiment 1B). Two accounts of this pattern of priming effects were proposed that postulate two different mechanisms over and above effects of visual acuity. The integration account postulates degree of separation of prime and target stimuli as the critical factor, and the attentional account postulates spatial attention as the critical factor. The results of Experiment 2, in which prime and target positions were manipulated orthogonally, were in favor of the attentional account. Repetition priming did not vary as a function of whether or not primes and targets appeared at the same location, but target processing was facilitated independently of priming when targets appeared at the same location as primes, especially in the right visual field.     

Top-down and bottom-up attentional control: on the nature of interference from a salient distractor.

In two experiments using spatial probes, we measured the temporal and spatial interactions between top-down control of attention and bottom-up interference from a salient distractor in visual search. The subjects searched for a square among circles, ignoring color. Probe response times showed that a color singleton distractor could draw attention to its location in the early stage of visual processing (before a 100-msec stimulus onset asynchrony [SOA]), but only when the color singleton distractor was located far from the target. Apparently the bottom-up activation of the singleton distractor's location is affected early on by local interactions with nearby stimulus locations. Moreover, probe results showed that a singleton distractor did not receive attention after extended practice. These results suggest that top-down control of attention is possible at an early stage of visual processing. In the long-SOA condition (150-msec SOA), spatial attention selected the target location over distractor locations, and this tendency occurred with or without extended practice.     

Effects of prime-target spatial separation and attentional deployment on masked repetition priming

In two masked repetition priming experiments with letter stimuli, the positions of prime and target stimuli were varied horizontally from fixation. Priming effects did not interact with position when prime and target location covaried (Experiment 1A) but diminished with increasing prime eccentricity when targets were always centrally located (Experiment 1B). Two accounts of this pattern of priming effects were proposed that postulate two different mechanisms over and above effects of visual acuity. The integration account postulates degree of separation of prime and target stimuli as the critical factor, and the attentional account postulates spatial attention as the critical factor. The results of Experiment 2, in which prime and target positions were manipulated orthogonally, were in favor of the attentional account. Repetition priming did not vary as a function of whether or not primes and targets appeared at the same location, but target processing was facilitated independently of priming when targets appeared at the same location as primes, especially in the right visual field.     

Inhibited prime-trial distractor responses solely produce the visual spatial negative priming effect

Responding to a target??s current (probe trial) location is slower when it appears at a former distractor-occupied position (i.e., ignored-repetition [IR] trial), relative to when it arises at a new location (i.e., control trial). This RT(IR) > RT(Control) inequality defines the spatial negative priming (SNP) effect in latency terms. It is uncertain whether the elevated RT(IR) is due to the inhibition of the distractor-occupied location or to the inhibition of this location??s assigned manual response (SNP locus issue). The main aim here was to examine the SNP locus issue. Notably, our SNP design used centrally presented visual events and included having two locations share a common response (many:1 location-to-response mapping) and the use of informative (70?% validity) or uninformative probe-trial response cues. The many:1 mapping trials allowed for the detection of location and response inhibition presence. Results showed that the latter, but not the former, causes inhibitory aftereffects (e.g., SNP) following uninformative response cues. Consistent with this finding, when the informative response cue was valid and was assigned to the many:1 probe response that had just served as the prime distractor response, inhibitory aftereffects were eliminated, when the probe target appeared at the prime distractor position (IR trial) or at a new location (distractor?Cresponse repeat trial). Blocked retrieval of stored distractor-processing representations was proposed as the mechanism for inhibitory aftereffect prevention.     

Identity and semantic negative priming in rapid serial visual presentation streams

In selective attention tasks, the efficiency of processing concurrently presented target and distractor stimuli in a given display is often influenced by the relationship these stimuli have with those in the previous display. When a to-be-attended target on a current trial (the probe trial) matches the ignored, non-target distractor on a previous trial (the prime trial), a response to the target is typically delayed compared with when the two stimuli are not associated. This negative priming (NP) phenomenon has been observed in numerous studies with traditional NP tasks presenting the target and distractor simultaneously in both the prime and probe trial couplets. Here, however, in four experiments using a mixture of stimulus types (letters, digits, English number words, and logographic Chinese number words), target and distractor stimuli were temporally separated in two rapid serial visual presentation (RSVP) streams instead of concurrently presented. The findings provide a conceptual replication and substantial extension of a recent study by Wong (Plos One, 7, e37023, 2012), and suggest that active suppression of irrelevant distracting information is a more ubiquitous form of cognitive control than previously thought.     

Spatial selection via feature-driven inhibition of distractor locations

The allocation of spatial attention was measured with detection probes at different locations. Response times were faster for probes at the location of the target digit, which subjects reported, than at the locations of distractor digits, which they ignored. Probes at blank locations between stimuli produced fast responses, indicating that selection was accomplished by inhibiting distractor locations but not other areas. Unlike earlier studies using location cuing with simpler stimuli, these experiments showed no attentional differences across horizontal or vertical midlines. Attention varied little with distance from the target, although blank locations far from the target were somewhat less attended than were those near the target, and attention was only slightly affected by expectations for stimulus location. This task demonstrates a form of feature-driven spatial attention, in which locations with objects lacking target features are inhibited.     

The control of saccade trajectories: direction of curvature depends on prior knowledge of target location and saccade latency

Recent reports have shown that saccades can deviate either toward or away from distractors. However, the specific conditions responsible for the change in initial saccade direction are not known. One possibility, examined here, is that the direction of curvature (toward or away from distractors) reflects preparatory tuning of the oculomotor system when the location of the target and distractor are known in advance. This was investigated by examining saccade trajectories under predictable and unpredictable target conditions. In Experiment 1, the targets and the distractors appeared unpredictably, whereas in Experiment 2 an arrow cue presented at fixation indicated the location of the forthcoming target prior to stimulus onset. Saccades were made to targets on the horizontal, vertical, and principal oblique axis, and distractors appeared simultaneously at an adjacent location (a separation of +/- 45 degrees of visual angle). On average, saccade trajectories curved toward distractors when target locations were unpredictable and curved away from distractors when target locations were known in advance. There was no overall difference in mean saccade latencies between the two experiments. The magnitude of the distractor modulation of saccade trajectory (either toward or away from) was comparable across the different saccade directions (horizontal, vertical, and oblique). These results are interpreted in terms of the time course of competitive interactions operating in the neural structures involved in the suppression of distractors and the selection of a saccade target. A relatively slow mechanism that inhibits movements to distractors produces curvature away from the distractor. This mechanism has more time to operate when target location is predictable, increasing the likelihood that the saccade trajectory will deviate away from the distractor.     

Revisiting the role of probe distractors in negative priming: Location negative priming is observed when probe distractors are consistently absent

Negative priming (NP) refers to the delayed response to a probe target that was previously a prime distractor. One peculiar problem in NP literature is the observation that the manifestation of identity NP is contingent on the presence and type of probe distractors. When the probe distractors were completely removed, positive priming, rather than NP, was usually observed. This study investigated whether location NP was affected by the same manipulations. The proportion of ignored repetition trials, attended repetition trials, and control trials was manipulated across Experiments 1–3. These three experiments showed reliable location NP effect when the probe distractor was consistently absent. Experiment 4 showed that the presence of probe distractors did not increase the magnitude of the location NP effect. Experiment 5 showed that the location NP effect observed was not contingent on perceptual mismatching. These findings suggest that the presence of probe distractors is not a necessary component for the manifestation of location NP. Theoretical implications were discussed.     

Prime-trial processing demands and their impact on distractor processing in a spatial negative priming task

A spatial negative priming (NP) paradigm was used where trials were presented in pairs, first the 'prime' and then the 'probe', and where participants responded manually to a target's location. In Experiment 1, three prime-trial types were used: distractor-plus-target, predictable distractor-only, and unpredictable distractor-only, with prime-probe trial onset delays of 2, 5 or 10 s (NP longevity). In Experiment 2, the latter two prime-trials were employed with onset delays of 75 and 750 ms (distractor response activation-inhibition sequence). With the exception of the 10 s onset delay, the spatial NP effect data (NP size, longevity, distractor response activation-inhibition sequence) was the same for all three prime-trial types. Thus, the varying processing demands associated with each of the prime-trial types (e.g., selection, intervening response) did not alter prime distractor processing so that they differentially contributed to the spatial NP process. The three prime-trial types can be used interchangeably, within limits, to study the NP process.