Subliminal Gestalt grouping: Evidence of perceptual grouping by proximity and similarity in absence of conscious perception

Previous studies making use of indirect processing measures have shown that perceptual grouping can occur outside the focus of attention. However, no previous study has examined the possibility of subliminal processing of perceptual grouping. The present work steps forward in the study of perceptual organization, reporting direct evidence of subliminal processing of Gestalt patterns. In two masked priming experiments, Gestalt patterns grouped by proximity or similarity that induced either a horizontal or vertical global orientation of the stimuli were presented as masked primes and followed by visible targets that could be congruent or incongruent with the orientation of the primes. The results showed a reliable priming effect in the complete absence of prime awareness for both proximity and similarity grouping principles. These findings suggest that a phenomenal report of the Gestalt pattern is not mandatory to observe an effect on the response based on the global properties of Gestalt stimuli.     

The attentional processes underlying impaired inhibition of threat in anxiety: The remote distractor effect

The current study explored the proposition that anxiety is associated with impaired inhibition of threat. Using a modified version of the remote distractor paradigm, we considered whether this impairment is related to attentional capture by threat, difficulties disengaging from threat presented within foveal vision, or difficulties orienting to task-relevant stimuli when threat is present in central, parafoveal and peripheral locations in the visual field. Participants were asked to direct their eyes towards and identify a target in the presence and absence of a distractor (an angry, happy or neutral face). Trait anxiety was associated with a delay in initiating eye movements to the target in the presence of central, parafoveal and peripheral threatening distractors. These findings suggest that elevated anxiety is linked to difficulties inhibiting task-irrelevant threat presented across a broad region of the visual field.     

The attentional processes underlying impaired inhibition of threat in anxiety: the remote distractor effect

The current study explored the proposition that anxiety is associated with impaired inhibition of threat. Using a modified version of the remote distractor paradigm, we considered whether this impairment is related to attentional capture by threat, difficulties disengaging from threat presented within foveal vision, or difficulties orienting to task-relevant stimuli when threat is present in central, parafoveal and peripheral locations in the visual field. Participants were asked to direct their eyes towards and identify a target in the presence and absence of a distractor (an angry, happy or neutral face). Trait anxiety was associated with a delay in initiating eye movements to the target in the presence of central, parafoveal and peripheral threatening distractors. These findings suggest that elevated anxiety is linked to difficulties inhibiting task-irrelevant threat presented across a broad region of the visual field.     

Selective attention and avoidance on a pictorial cueing task during stress in clinically anxious and depressed participants

Although it is well established that attentional biases exist in anxious populations, the specific components of visual orienting towards and away from emotional stimuli are not well delineated. The present study was designed to examine these processes. We used a modified spatial cueing task to assess the speed of engagement and disengagement from supraliminal and masked pictorial cues depicting threat, dysphoria, or neutral content in 36 clinically anxious, 41 depressed and 41 control participants. Participants were randomly assigned to a stress or neutral condition. During stress, anxious participants were slow to disengage from masked left hemifield pictures depicting threat or dysphoria, but were quick to disengage from supraliminal threat pictures. Information processing in anxious participants during stress was characterized by early selective attention of emotional stimuli, occurring prior to full conscious awareness, followed by effortful avoidance of threat. Depressed participants were distinct from the anxious group, displaying selective attention for stimuli depicting dysphoria, but not threat, during the neutral condition. In sum, attentional biases in clinical populations are associated with difficulties in the disengagement component of visual orienting. Further, a vigilant-avoidant pattern of attentional bias may represent a strategic attempt to compensate for the early activation of a fear response.     

Exogenous attention to angry faces in social anxiety: a perceptual accuracy approach

We investigated the interaction between endogenous and exogenous attention for the processing of emotional stimuli in individuals with high social anxiety using accuracy rates. Following the presentation of an endogenous cue at the centre, exogenous cues (i.e., angry and neutral faces) were presented at peripheral locations. Subsequently, non-emotional masked targets were presented, and the participants were instructed to discriminate between the targets. With respect to exogenous attention, high socially anxious people exhibited higher accuracy when the angry face and target appeared on the same side than when they appeared on different sides, whereas low socially anxious people did not exhibit such effects. On the other hand, different abilities of endogenous attention were not observed between high and low socially anxious people. These results suggest that exogenous attention is biased towards threat in high socially anxious people.     

Exogenous attention to angry faces in social anxiety: A perceptual accuracy approach

We investigated the interaction between endogenous and exogenous attention for the processing of emotional stimuli in individuals with high social anxiety using accuracy rates. Following the presentation of an endogenous cue at the centre, exogenous cues (i.e., angry and neutral faces) were presented at peripheral locations. Subsequently, non-emotional masked targets were presented, and the participants were instructed to discriminate between the targets. With respect to exogenous attention, high socially anxious people exhibited higher accuracy when the angry face and target appeared on the same side than when they appeared on different sides, whereas low socially anxious people did not exhibit such effects. On the other hand, different abilities of endogenous attention were not observed between high and low socially anxious people. These results suggest that exogenous attention is biased towards threat in high socially anxious people.     

Conscious intrusion of threat information via unconscious priming in anxiety

Preferential processing of threat has been implicated in the development and perpetuation of anxiety. We investigated threat processing and anxiety using a subliminal priming paradigm. People with high or low trait anxiety viewed masked, briefly presented words, and then took an exclusion-completion test in which three-letter stems were to be completed without using recently perceived words. Completion rates were greater for words viewed subliminally compared to a baseline estimate. In addition, unconscious priming was greater for threat than for neutral words in the high-trait-anxiety group, and for neutral than for threat words in the low-trait-anxiety group. Enhanced unconscious priming of threat completions among anxious individuals may model intrusions in anxiety, when unconscious processing breaks into consciousness in the form of threat-related intrusive thoughts.     

Faces, flowers and football boots: capacity limits in distractor processing

While visual attention can be attracted by task-irrelevant stimuli, questions remain regarding how many irrelevant items can be processed simultaneously and whether capacity limits are equivalent for all types of stimuli. To explore these issues, participants were required to classify verbal stimuli that were flanked by either one or two response-matching or response-mismatching faces (Expts. 1 and 2) or objects (Expt. 2). The results revealed that when stimulus categorization was sufficient to trigger flanker interference, distractor processing was insensitive to the number of irrelevant stimuli. When, however, stimulus identification was needed to drive flanker interference, distractor processing was attenuated when two task-irrelevant items were presented. The theoretical implications of these findings are considered.     

Anxiety sensitivity: the role of conscious awareness and selective attentional bias to physical threat

Selective attentional biases were examined amongst individuals varying in levels of physical anxiety sensitivity. The dot-probe paradigm was used to examine attention towards anxiety symptomatology, social threat and positive words. Stimuli were presented above (unmasked) and below (masked) the level of conscious awareness. High physical anxiety sensitivity was associated with attentional vigilance for anxiety symptomatology words in both unmasked and masked conditions. For positive words, however, those high in anxiety sensitivity were found to avoid such stimuli when they were masked, whereas they exhibited a relative vigilance when unmasked. If the differences between awareness conditions are reliable, then the impact of the automatic vigilance for threat might be modified by conscious attempts to direct attention towards other types of stimuli.     

Semantic priming: subliminal perception or context?

Briefly presented, masked priming stimuli that cannot be identified by themselves can affect the processing of subsequent targets. The effect, which is sometimes viewed as a demonstration of unconscious processing, has been linked to the subliminal perception literature. Experiments 1 and 2 indicated that the identification of primes in the context of semantically related targets is superior to the identification of primes presented alone, and that the identification of primes in the context of semantically unrelated targets is inferior to the identification of primes presented alone. Experiment 3 indicated parallel findings in a recognition task. Consequently, an explanation of semantic priming in terms of the interactive nature of stimuli that are near to one another in time seems preferable to one based upon concepts of unconscious processing and subliminal perception.     

Inhibition of return in subliminal letter priming

The present study combined exogenous spatial cueing with masked repetition priming to study attentional influences on the processing of subliminal stimuli. Participants performed an alphabetic decision task (letter versus pseudo-letter classification) with central targets and briefly presented peripherally located primes that were either cued or not cued by an abrupt onset. A relatively long delay between cue and prime was used to investigate the effect of inhibition of return (IOR) on the processing of subliminal masked primes. Primes presented to the left visual field showed standard effects of Cue Validity and no IOR (significant priming with valid cues only). Primes presented to the right visual field showed no priming from valid cues (an IOR effect), and priming with invalid cues that depended on hand of response to letter targets (right-hand in Experiment 1, left-hand in Experiment 2). The results are interpreted in terms of a differential speed of engagement and disengagement of attention to the right and left visual fields for alphabetic stimuli, coupled with a complex interaction that arises between Prime Relatedness and response-hand.     

Anxiety, conscious awareness and change detection

Attentional scanning was studied in anxious and non-anxious participants, using a modified change detection paradigm. Participants detected changes in pairs of emotional scenes separated by two task irrelevant slides, which contained an emotionally valenced scene (the 'distractor scene') and a visual mask. In agreement with attentional control theory, change detection latencies were slower overall for anxious participants. Change detection in anxious, but not non-anxious, participants was influenced by the emotional valence and exposure duration of distractor scenes. When negative distractor scenes were presented at subliminal exposure durations, anxious participants detected changes more rapidly than when supraliminal negative scenes or subliminal positive scenes were presented. We propose that for anxious participants, subliminal presentation of emotionally negative distractor scenes stimulated attention into a dynamic state in the absence of attentional engagement. Presentation of the same scenes at longer exposure times was accompanied by conscious awareness, attentional engagement, and slower change detection.     

Trait anxiety modulates supraliminal and subliminal threat: Brain potential evidence for early and late processing influences

Analysis of threat is thought to involve a “quick and dirty” stage in conjunction with slower processing that is more complete. We investigated both types of threat analysis by recording brain potentials in response to threat and neutral words. Personality testing was used to identify participants who were either high or low in trait anxiety (TA). An observed enhancement of occipital P1 potentials to threat words during an emotional Stroop task was interpreted as a signal of unconscious processing, since it was early, independent of whether word exposure was subliminal or supraliminal, and more prominent the higher the level of TA. Later positive potentials were also enhanced for threat versus neutral words, but the amplitude enhancement increased with higher TA only in the subliminal condition. These results suggest that unconscious analysis of threat is intensified in those prone to anxiety, as is a later stage of threat processing subject to dynamic interactions between automatic and strategic influences.     

Nonconcurrently presented auditory tones reduce distraction

Recent research has demonstrated that task-irrelevant stimuli presented simultaneously with a target-distractor stimulus reduce distraction and improve selective attention. In studies examining this reduced interference effect, visual selective attention tasks and concurrently presented task-irrelevant stimuli are used. We report first evidence for a similar effect in the auditory domain and with nonconcurrent stimuli (i.e., the task-irrelevant stimuli are presented before the target). The effect of nonconcurrently presented auditory tones on an auditory Stroop task developed by Leboe and Mondor (Psychological Research, 71, 568--575, 2007) was investigated. Stroop interference was reduced when task-irrelevant tones were presented before the Stroop stimulus. We conclude that task-irrelevant stimuli can improve selective attention not only when presented concurrently, but also when presented before the selective attention task. Our results are consistent with the hypothesis that interference reduction is due to perceptual dilution caused by task-irrelevant stimuli.     

Exploring linguistic correlates of social anxiety in romantic stories

The current study used computerized linguistic analysis of stories about either going on a date or taking a walk down a street to examine linguistic correlates of social anxiety in a sample of undergraduate students. In general, linguistic analysis revealed associations of social anxiety with several linguistic variables, including negative emotion, affect, and anxiety words. Participants higher in social anxiety wrote fewer affect words. The relationship between social anxiety and anxiety words depended on gender, whereas the relationship between social anxiety and negative emotion words depended on both gender and the nature of primes (supraliminal vs. subliminal) received. Overall, our findings highlight the potential utility and benefits of using linguistic analysis as another source of information about how individuals higher in social anxiety process romantic stimuli.     

Selective attention for masked and unmasked threatening words in anxiety: Effects of trait anxiety, state anxiety and awareness

We investigated the effects of awareness on selective attention for masked and unmasked verbal threat material using a computerised version of the emotional Stroop. Participants were assigned to the high trait anxious (HTA) and low trait anxious (LTA) groups on the basis of questionnaire scores, and state anxiety was manipulated within participants through the threat of electric shock. To investigate the effects of awareness on responses to threat, the mode of exposure was blocked such that half the participants received masked trials before the unmasked trials, whereas the other half received the reverse order. The results revealed that there was no difference between the HTA and LTA groups in responses to threat for those who received the masked trials before the unmasked trials. However, when unmasked trials were presented before the masked trials HTA individuals were significantly slower to respond to both masked and unmasked threat words compared to the LTA group, and these effects were not further modified by participants' state anxiety status. The results are discussed in terms of the automatic nature of threat processing in anxiety.     

Subliminal speech perception and auditory streaming

Current theories of consciousness assume a qualitative dissociation between conscious and unconscious processing: while subliminal stimuli only elicit a transient activity, supraliminal stimuli have long-lasting influences. Nevertheless, the existence of this qualitative distinction remains controversial, as past studies confounded awareness and stimulus strength (energy, duration). Here, we used a masked speech priming method in conjunction with a submillisecond interaural delay manipulation to contrast subliminal and supraliminal processing at constant prime, mask and target strength. This delay induced a perceptual streaming effect, with the prime popping out in the supraliminal condition. By manipulating the prime-target interval (ISI), we show a qualitatively distinct profile of priming longevity as a function of prime awareness. While subliminal priming disappeared after half a second, supraliminal priming was independent of ISI. This shows that the distinction between conscious and unconscious processing depends on high-level perceptual streaming factors rather than low-level features (energy, duration).     

Affective significance enhances covert attention: Roles of anxiety and word familiarity

To investigate the processing of emotional words by covert attention, threat-related, positive, and neutral word primes were presented parafoveally (2.2° away from fixation) for 150 ms, under gaze-contingent foveal masking, to prevent eye fixations. The primes were followed by a probe word in a lexical-decision task. In Experiment 1, results showed a parafoveal threat–anxiety superiority: Parafoveal prime threat words facilitated responses to probe threat words for high-anxiety individuals, in comparison with neutral and positive words, and relative to low-anxiety individuals. This reveals an advantage in threat processing by covert attention, without differences in overt attention. However, anxiety was also associated with greater familiarity with threat words, and the parafoveal priming effects were significantly reduced when familiarity was covaried out. To further examine the role of word knowledge, in Experiment 2, vocabulary and word familiarity were equated for low- and high-anxiety groups. In these conditions, the parafoveal threat–anxiety advantage disappeared. This suggests that the enhanced covert-attention effect depends on familiarity with words.     

非自主闯入焦虑发生的机制：阈下启动效应的实验研究

本研究采用阈下情感启动范式, 研究威胁信息启动效应及其特质焦虑的调节作用,旨在揭示焦虑非自主闯入性特点形成的机制。实验在随机的三种条件下（阈上/阈下/基线）给38名被试呈现两种目标词（威胁词和中性词）,其中基线条件不呈现目标词;之后要求被试在回避目标词的条件下完成组词任务,结果：（1）无论是中性词还是威胁词,被试阈下条件下目标词的击中率显著高于基线条件;（2）特质焦虑对阈下启动效应起着调节作用：高焦虑组被试威胁词的启动效应显著高于中性词,低焦虑组被试中性词的启动效应显著高于威胁词。结论：阈下启动效应显著,高特质焦虑组个体对威胁信息的无意识加工会增强对威胁信息的意识加工,产生闯入性想法,导致焦虑非自主闯入性的特点。     

Processing of task-irrelevant natural scenes in social anxiety

In this study, by manipulating perceptual load, we investigated whether socially anxious people process task-irrelevant, non-emotional, natural scenes. When attention was directed to letters and perceptual load was low, task-irrelevant natural scenes were processed, as evidenced by repetition priming effects, in both high and low socially anxious people. In the high perceptual load condition, repetition-priming effects decreased in participants with low social anxiety, but not in those with high social anxiety. The results were the same when attention was directed to pictures of animals: even in the high perceptual load condition, high socially anxious participants processed task-irrelevant natural scenes, as evidenced by flanker effects. However, when attention was directed to pictures of people, task-irrelevant natural scenes were not processed by participants in either anxiety group, regardless of perceptual load. These results suggest that high socially anxious individuals could not inhibit task-irrelevant natural scenes under conditions of high perceptual load, except when attention was focused on people.