Subliminal perception of others' physical pain induces personal distress rather than empathic concern

BACKGROUND

What is our immediate reaction when we witness someone experiencing pain? The empathy-altruism hypothesis predicts that observers would display empathy and a tendency to approach the person in pain. Alternatively, the threat value of pain hypothesis (TVPH) argues that others' pain serves as a signal of threat and should induce observers' avoidance response.

METHODS

To examine these two hypotheses, three experiments were conducted. The experiments aimed to investigate the impact of subliminal exposure to others' physical pain on participants' emotional and behavioural responses.

RESULTS

The results revealed that subliminal pain priming resulted in faster response and attentional bias to fearful faces compared to sad faces (Experiment 1), faster reaction times in recognizing fear-related words compared to anger-related words during a lexical decision task (Experiment 2), and faster avoidance responses towards anger-related words, as opposed to approaching responses towards positive words (Experiment 3).

CONCLUSIONS

The consistent findings across all experiments revealed that subliminal perception of pain scenes elicited fear emotion and immediate avoidance responses. Therefore, the outcomes of our study provide supportive evidence for the TVPH.

The contribution of subliminal perceptions, dietary habits, and psychological traits to the perception of oral tingling and burning sensations

The tingling evoked by Sichuan pepper and the burning elicited by chili pepper constitutes the typical flavor of Sichuan cuisine and is a component of leisure food. Although factors affecting the burning sensation have extensively been studied, few studies have examined the factors of individual sensitivity, personality traits, and dietary habits that contribute to the perception of oral tingling sensation, which hinders the formulation of tingling products and the development of new products. In contrast, many studies have examined the factors influencing the burning sensation. In this web-based survey, 68 participants disclosed their dietary habits, liking for tingling and hot foods, and psychological traits. Individual sensitivity to the tingling and burning sensation produced by a range of Sichuan pepper oleoresin and capsaicin solutions was determined using rated differences from control, generalized labeled magnitude scale method and ranking test. The consistency score indicated the accuracy of individual ranking results while also providing an indirect response to the sensitivity of the participant to supra-threshold for burning or tingling. Individual ratings for medium Sichuan pepper oleoresin concentrations significantly correlated with the just noticeable difference (p < 0.01), and ratings for medium and high capsaicin concentrations correlated significantly with 6-n-propylthiouracil ratings (p < 0.01). Notably, the power exponent of burning was significantly correlated with the burning recognition threshold (p < 0.01), and the power exponent of tingling and burning were significantly correlated (r = 0.340, p < 0.05). There was a negative correlation between supra-threshold tingling and burning sensation perceptions and life satisfaction ratings. Further, intensity ratings for oral tingling and burning sensation did not always correspond with individual sensitivity indicators (e.g., recognition threshold, 6-n-propylthiouracil, just noticeable difference, and consistency score). Thus, this study provides new insight into establishing a sensory selection method for chemesthetic sensation panelists and theoretical guidelines for formulation design and in-depth analysis of popular tingling dishes and foods.

Diffusion model-based understanding of subliminal affective priming in continuous flash suppression

Affective states influence our decisions even when processed unconsciously. Continuous flash suppression (CFS) is a new variant of binocular rivalry that can be used to render the prime subliminal. Nonetheless, how prior information from emotional faces suppressed by CFS influences subsequent decision-making remains unclear. Here, we employed a CFS priming task to examine the effect of the two main types of information conveyed by faces, i.e., facial identity and emotion, on the evaluation of target words as positive or negative. The hierarchical diffusion model was used to investigate the underlying mechanisms. A significant interaction effect on response time was observed following the angry face prime but not the happy or neutral face primes. The results of the diffusion model analyses revealed that the priming effects of facial identity were mapped onto the drift rate and erased the 'positive bias' (the processing advantage of positive over negative stimuli). Meanwhile, the positive emotional faces increased the nondecision time in response to negative target words. The model-based analysis implies that both facial identity and emotion are processed under CFS.

Predictions from masked motion with and without obstacles

Predicting the future is essential for organisms like Homo sapiens, who live in a dynamic and ever-changing world. Previous research has established that conscious stimuli can lead to non-conscious predictions. Here we examine whether masked stimuli can also induce such predictions. We use masked movement-with and without obstacles-to examine predictions from masked stimuli. In six experiments a moving object was masked using continuous flash suppression (CFS). A few hundred milliseconds after the object had disappeared, a conscious probe appeared in a location that was either consistent with the masked stimulus or not. In Experiments 1-3 the movement was linear, and reaction times (RTs) indicated predictions that were based on direction and speed of movement. In Experiment 4, the masked moving object collided with an obstacle and then disappeared. Predictions in this case should reflect deflection, and indeed reaction times revealed predictions on the deflection route. In Experiments 5 and 6 we introduce an innovative way of using eye-tracking during continuous flash suppression (CFS) and report physiological evidence-in the forms of eye-movements-for masked stimuli induced predictions. We thus conclude that humans can use dynamic masked stimuli to generate active predictions about the future, and use these predictions to guide behavior. We also discuss the possible interpretations of these findings in light of the current scientific discussion regarding the relation between masked presentation, subliminal perception and awareness measurement methods.

Disentangling the Roles of Cue Visibility and Knowledge in Adjusting Cognitive Control: A Preregistered Direct Replication of the Farooqui and Manly (2015) Study

Recent research suggests that people can learn to link the control process of task switching to predictive cues so that switch costs are attenuated following informative precues of switch likelihood. However, the precise conditions that shape such contextual cuing of control are not well understood. Farooqui and Manly (2015) raised the possibility that cued task switching is more effective when cues of control demand are presented subliminally. In the current study, we aimed to replicate and extend these findings by more systematically manipulating whether cues of control demand are consciously perceived or are presented subliminally and whether participants have explicit prior knowledge of the cue meaning or acquire cue knowledge through experience. The direct replication was unsuccessful: We found no evidence for effective subliminal cuing but observed some evidence for participants reducing switch costs with explicit, supraliminal cues. Thus, cognitive control may be guided most effectively by explicitly understood and consciously perceived precues.

Contextual knowledge provided by a movie biases implicit perception of the protagonist

We are constantly categorizing other people as belonging to our in-group (‘one of us’) or out-group (‘one of them’). Such grouping occurs fast and automatically and can be based on others’ visible characteristics such as skin color or clothing style. Here we studied neural underpinnings of implicit social grouping not often visible on the face, male sexual orientation. A total of 14 homosexuals and 15 heterosexual males were scanned in functional magnetic resonance imaging while watching a movie about a homosexual man, whose face was also presented subliminally before (subjects did not know about the character’s sexual orientation) and after the movie. We discovered significantly stronger activation to the man’s face after seeing the movie in homosexual but not heterosexual subjects in medial prefrontal cortex, frontal pole, anterior cingulate cortex, right temporal parietal junction and bilateral superior frontal gyrus. In previous research, these brain areas have been connected to social perception, self-referential thinking, empathy, theory of mind and in-group perception. In line with previous studies showing biased perception of in-/out-group faces to be context dependent, our novel approach further demonstrates how complex contextual knowledge gained under naturalistic viewing can bias implicit social perception.

The effect of emotional information from eyes on empathy for pain: A subliminal ERP study

Facial expressions are deeply tied to empathy, which plays an important role during social communication. The eye region is effective at conveying facial expressions, especially fear and sadness emotions. Further, it was proved that subliminal stimuli could impact human behavior. This research aimed to explore the effect of subliminal sad, fearful and neutral emotions conveyed by the eye region on a viewer's empathy for pain using event-related potentials (ERP). The experiment used an emotional priming paradigm of 3 (prime: subliminal neutral, sad, fear eye region information) × 2 (target: painful, nonpainful pictures) within-subject design. Participants were told to judge whether the targets were in pain or not. Results showed that the subliminal sad eye stimulus elicited a larger P2 amplitude than the subliminal fearful eye stimulus when assessing pain. For P3 and late positive component (LPC), the amplitude elicited by the painful pictures was larger than the amplitude elicited by the nonpainful pictures. The behavioral results demonstrated that people reacted to targets depicting pain more slowly after the sad emotion priming. Moreover, the subjective ratings of Personal Distress (PD) (one of the dimensions in Chinese version of Interpersonal Reactivity Index scale) predicted the pain effect in empathic neural responses in the N1 and N2 time window. The current study showed that subliminal eye emotion affected the viewer's empathy for pain. Compared with the subliminal fearful eye stimulus, the subliminal sad eye stimulus had a greater impact on empathy for pain. The perceptual level of pain was deeper in the late controlled processing stage.

Romantic Love and Attentional Biases Toward Attractive Alternatives and Rivals: Long-Term Relationship Maintenance Among Female Chinese College Students

Studies about heterosexual individuals' long-term relationship maintenance have indicated that committed individuals possess evolved psychological mechanisms that help protect their ongoing romantic relationships against threats from attractive others during early stage attentional processing when mating-related motivation is activated. In this study, two experiments tested the relationship maintenance mechanism among committed female college students in the Chinese cultural context under different love priming conditions. Committed Chinese women displayed inattention to attractive alternatives in positive love-scenario priming (Study 1: 114 female undergraduates, age range = 18-26 years), subliminal semantic love priming (Study 2: 110 female undergraduates, age range = 18-25 years), and baseline conditions (Studies 1 and 2). Those with high levels of chronic jealousy showed significantly increased attention to and difficulty disengaging attention from attractive rivals when subliminally primed with love. This provides further evidence, from an Eastern cultural context, for the existence of attentional biases toward attractive alternatives and rivals in early stage attentional processes for relationship maintenance. This research also illustrates the important role of romantic love in maintaining long-term romantic relationships.

How the Brain Transitions from Conscious to Subliminal Perception

We study the transition in the functional networks that characterize the human brains' conscious-state to an unconscious subliminal state of perception by using k-core percolation. We find that the most inner core (i.e., the most connected kernel) of the conscious-state functional network corresponds to areas which remain functionally active when the brain transitions from the conscious-state to the subliminal-state. That is, the inner core of the conscious network coincides with the subliminal-state. Mathematical modeling allows to interpret the conscious to subliminal transition as driven by k-core percolation, through which the conscious state is lost by the inactivation of the peripheral k-shells of the conscious functional network. Thus, the inner core and most robust component of the conscious brain corresponds to the unconscious subliminal state. This finding imposes constraints to theoretical models of consciousness, in that the location of the core of the functional brain network is in the unconscious part of the brain rather than in the conscious state as previously thought.

Does the implicit outcomes expectancies shape learning and memory processes?

Does the explicit or implicit knowledge about the consequences of our choices shape learning and memory processes? This seems to be the case according to previous studies demonstrating improvements in learning and retention of symbolic relations and in visuospatial recognition memory when each correct choice is reinforced with its own unique and explicit outcome (the differential outcomes procedure, DOP). In the present study, we aim to extend these findings by exploring the impact of the DOP under conditions of non-conscious processing. To test for this, both the outcomes (Experiment 1A) and the sample stimuli (Experiment 1B) were presented under subliminal (non-conscious) and supraliminal conditions in a delayed visual recognition memory task. Results from both experiments showed a better visual recognition memory when participants were trained with the DOP regardless the awareness of the outcomes or even of the stimuli used for training. To our knowledge, this is the first demonstration that the DOP can be effective under unconscious conditions. This finding is discussed in the light of the two-memory systems model developed by Savage and colleagues to explain the beneficial effects observed on learning and memory when differential outcomes are applied.

Conceptual priming and context reinstatement: A test of direct and indirect interview techniques

Recent findings suggest that priming may be useful for facilitating disclosure in investigative interviews; however, the effects of priming on behavioral outcomes have been mixed. The current studies attempted to replicate the increase in information disclosure when the concept of "openness" is primed. We assessed the separate and combined influence of context reinstatement instructions and activation of the concept of openness (via lexical primes in Experiment 1, via contextual and embodiment primes in Experiment 2) on information disclosure. In doing so, we introduced a novel paradigm to investigate factors contributing to the elicitation of sensitive personal information that participants provided in written (Experiment 1) or verbal (Experiment 2) form. Participants (Experiment 1: N = 173; Experiment 2: N = 194) completed a checklist of illegal behaviors and misdeeds, then engaged in an unrelated task that was used to administer the priming manipulation (either the concept of "open" or "closed," or a neutral prime). Participants then described a life event related to the most serious illegal behavior to which they had admitted, following either a direct request for information or a context reinstatement instruction. Across both experiments, context reinstatement led to robust increases in information disclosure. Although we failed to replicate prior effects of priming on disclosure, our observed effect sizes fell within the confidence intervals of previous studies. A meta-analytic assessment of priming across the two studies suggested a small but significant increase in information elicitation, suggesting that investigators are best served using evidence-based interviewing tactics during investigative interviews. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Psychophysiological Responses to Subliminal Auditory Suggestions for Activation,

The aim of this study was to characterize further the experimental procedure proposed by Borgeat and Goulet in 1983. Subliminal activation auditory suggestions were expected to increase heart rate and skin conductance in presence of a stressing task. 20 subjects were alternately exposed to activating or neutral (random numbers) 25-dB suggestions masked by a 40-dB white noise. Analyses of variance and covariance indicated an effect of the activating suggestions on heart rate but not on skin conductance. Partly confirming previous results, the data support the reliability of heart rate and the importance of a stressing factor to reveal the effects of preconscious or subliminal stimulations.

Nonconscious Perception, Where are You?

In three studies, no evidence of nonconscious perception was found, although general procedures used in previous studies reporting the effect were followed. Presence/absence thresholds (Exps. 1 and 2) or recognition threshold (Exp. 3) were established for each subject. There was no difference in the effects of related and unrelated primes on voice reaction time during a word naming task. These findings raise questions about the robustness of nonconscious priming effects.

Subliminal and supraliminal processing of reward-related stimuli in anorexia nervosa

BACKGROUND

Previous studies have highlighted the role of the brain reward and cognitive control systems in the etiology of anorexia nervosa (AN). In an attempt to disentangle the relative contribution of these systems to the disorder, we used functional magnetic resonance imaging (fMRI) to investigate hemodynamic responses to reward-related stimuli presented both subliminally and supraliminally in acutely underweight AN patients and age-matched healthy controls (HC).

METHODS

fMRI data were collected from a total of 35 AN patients and 35 HC, while they passively viewed subliminally and supraliminally presented streams of food, positive social, and neutral stimuli. Activation patterns of the group × stimulation condition × stimulus type interaction were interrogated to investigate potential group differences in processing different stimulus types under the two stimulation conditions. Moreover, changes in functional connectivity were investigated using generalized psychophysiological interaction analysis.

RESULTS

AN patients showed a generally increased response to supraliminally presented stimuli in the inferior frontal junction (IFJ), but no alterations within the reward system. Increased activation during supraliminal stimulation with food stimuli was observed in the AN group in visual regions including superior occipital gyrus and the fusiform gyrus/parahippocampal gyrus. No group difference was found with respect to the subliminal stimulation condition and functional connectivity.

CONCLUSION

Increased IFJ activation in AN during supraliminal stimulation may indicate hyperactive cognitive control, which resonates with clinical presentation of excessive self-control in AN patients. Increased activation to food stimuli in visual regions may be interpreted in light of an attentional food bias in AN.

Converging evidence that subliminal evaluative conditioning does not affect self-esteem or cardiovascular activity

Self-esteem moderates the relationship between stress and (cardiovascular) health, with low self-esteem potentially exacerbating the impact of stressors. Boosting self-esteem may therefore help to buffer against stress. Subliminal evaluative conditioning (SEC), which subliminally couples self-words with positive words, has previously been successfully used to boost self-esteem, but the existing studies are in need of replication. In this article, we aimed to replicate and extend previous SEC studies. The first 2 experiments simultaneously examined whether SEC increased self-esteem (Experiment 1, n = 84) and reduced cardiovascular reactivity to a stressor in high worriers (Experiment 2, n = 77). On the basis of these results, the 3rd experiment was set up to examine whether an adjusted personalized SEC task increased self-esteem and reduced cardiac activity in high worriers (n = 81). Across the 3 experiments, no effects were found of SEC on implicit or explicit self-esteem or affect or on cardiovascular (re)activity compared to a control condition in which the self was coupled with neutral words. The results do not support the use of the subliminal intervention in its current format. As stress is highly prevalent, future studies should focus on developing other cost-effective and evidence-based interventions.

ADHD patients fail to maintain task goals in face of subliminally and consciously induced cognitive conflicts

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) patients have been reported to display deficits in action control processes. While it is known that subliminally and consciously induced conflicts interact and conjointly modulate action control in healthy subjects, this has never been investigated for ADHD.

METHOD

We investigated the (potential) interaction of subliminally and consciously triggered response conflicts in children with ADHD and matched healthy controls using neuropsychological methods (event-related potentials; ERPs) to identify the involved cognitive sub-processes.

RESULTS

Unlike healthy controls, ADHD patients showed no interaction of subliminally and consciously triggered response conflicts. Instead, they only showed additive effects as their behavioural performance (accuracy) was equally impaired by each conflict and they showed no signs of task-goal shielding even in cases of low conflict load. Of note, this difference between ADHD and controls was not rooted in early bottom-up attentional stimulus processing as reflected by the P1 and N1 ERPs. Instead, ADHD showed either no or reversed modulations of conflict-related processes and response selection as reflected by the N2 and P3 ERPs.

CONCLUSION

There are fundamental differences in the architecture of cognitive control which might be of use for future diagnostic procedures. Unlike healthy controls, ADHD patients do not seem to be endowed with a threshold which allows them to maintain high behavioural performance in the face of low conflict load. ADHD patients seem to lack sufficient top-down attentional resources to maintain correct response selection in the face of conflicts by shielding the response selection process from response tendencies evoked by any kind of distractor.

Immediate effect of subliminal priming with positive reward stimuli on standing balance in healthy individuals: A randomized controlled trial

BACKGROUND

Information received subconsciously can influence exercise performance; however, it remains unclear whether subliminal or supraliminal reward is more effective in improving standing balance ability when priming stimuli are subconsciously delivered. The present study aimed to compare the effects of subliminal priming-plus-subliminal reward stimuli (experimental) with subliminal priming-plus-supraliminal reward stimuli (control) on standing balance ability.

METHODS

This was a single-blind (outcome assessor), parallel-group, randomized controlled trial involving healthy young adults recruited from a university in Japan. Assessments were conducted at baseline and immediately after intervention. The primary outcome was the functional reach test (FRT) measurement. The secondary outcome was one-leg standing time (OLST) with eyes closed. Of the 52 participants screened, 25 were randomly assigned to experimental and control groups each.

RESULTS

Both interventions were effective for improving the FRT between the baseline and intervention; however, smaller improvements were observed in the experimental group. We found a large between-groups effect size immediately after the intervention for the FRT (d = -0.92). In contrast, there were no differences in improvements in OLST between the 2 groups (d = -0.06); furthermore, neither intervention was found to be effective for this parameter.

CONCLUSION

We concluded that subliminal priming with conscious reward stimuli results in improvements in immediate-term forward reach ability, which is superior to that achieved by subliminal priming with subconscious reward stimuli.

The role of attention in subliminal semantic processing: A mouse tracking study

Recent evidence suggests that top-down attention facilitates unconscious semantic processing. To clarify the role of attention in unconscious semantic processing, we traced trajectories of the computer mouse in a semantic priming task and scrutinized the extent to which top-down attention enhances unconscious semantic processing in four different stimulus-onset asynchrony (SOA: 50, 200, 500, or 1000ms) conditions. Participants judged whether a target digit (e.g., “6”) was larger or smaller than five, preceded by a masked priming digit (e.g., “9”). The pre-prime duration changed randomly from trial to trial to disrupt participants’ top-down attention in an uncued condition (in a cued condition, a green square cue was presented to facilitate participants’ top-down attention). The results show that top-down attention modifies the time course of subliminal semantic processing, and the temporal attention window lasts more than 1000ms; attention facilitated by the cue may amplify semantic priming to some extent, yet the amplification effect of attention is relatively minor.

Orienting of attention with and without cue awareness

Many cognitive processes operate without consciousness, and exogenous attentional capture seems to be one of them. While endogenously attending to the opposite location of a cue cannot occur without cue awareness, attending the cued location in an exogenous or stimulus driven form can occur even when participants are not aware of the presence of the cue (McCormick, 1997). Orienting attention to a specific location shortens reaction times to supra-threshold stimuli, and increases the likelihood of consciously perceiving near-threshold stimuli in that location. Effects of unconscious cues have mostly been demonstrated in reaction times to supra-threshold targets. In some studies, unconscious cues were perceptually less salient than conscious cues, which introduced a confound between cue awareness and cue saliency. In the present study, we used near-threshold cues and targets, which were titrated to be consciously perceived in ~50% of the trials, therefore eliminating the cue saliency confound. Moreover, we explored for the first time the effects of cue awareness on the conscious perception of subsequently presented near-threshold targets. Our results demonstrate that when cues and targets did not spatially overlap, conscious cues enhanced target localization when they appeared near the target location. In contrast, non-consciously perceived cues impaired target localization when they appeared near the target location, producing a cost in detecting subsequently presented near-threshold targets. This indicates that attentional orienting by unconscious cues cannot be accounted for by the idea that attention modulates perceptual representations, boosting them nearer to the conscious threshold. Rather, the effect of unconscious cues on target localization is qualitatively different to that elicited by conscious cues.

Subliminal perception of complex visual stimuli

Rationale: Unconscious perception of various sensory modalities is an active subject of research though its function and effect on behavior is uncertain. Objective: The present study tried to assess if unconscious visual perception could occur with more complex visual stimuli than previously utilized. Methods and Results: Videos containing slideshows of indifferent complex images with interspersed frames of interest of various durations were presented to 24 healthy volunteers. The perception of the stimulus was evaluated with a forced-choice questionnaire while awareness was quantified by self-assessment with a modified awareness scale annexed to each question with 4 categories of awareness. At values of 16.66 ms of stimulus duration, conscious awareness was not possible and answers regarding the stimulus were random. At 50 ms, nonrandom answers were coupled with no self-reported awareness suggesting unconscious perception of the stimulus. At larger durations of stimulus presentation, significantly correct answers were coupled with a certain conscious awareness. Discussion: At values of 50 ms, unconscious perception is possible even with complex visual stimuli. Further studies are recommended with a focus on a range of interest of stimulus duration between 50 to 16.66 ms.

Subliminal stimulation and somatosensory signal detection

Only a small fraction of sensory signals is consciously perceived. The brain's perceptual systems may include mechanisms of feedforward inhibition that protect the cortex from subliminal noise, thus reserving cortical capacity and conscious awareness for significant stimuli. Here we provide a new view of these mechanisms based on signal detection theory, and gain control. We demonstrated that subliminal somatosensory stimulation decreased sensitivity for the detection of a subsequent somatosensory input, largely due to increased false alarm rates. By delivering the subliminal somatosensory stimulus and the to-be-detected somatosensory stimulus to different digits of the same hand, we show that this effect spreads across the sensory surface. In addition, subliminal somatosensory stimulation tended to produce an increased probability of responding "yes", whether the somatosensory stimulus was present or not. Our results suggest that subliminal stimuli temporarily reduce input gain, avoiding excessive responses to further small inputs. This gain control may be automatic, and may precede discriminative classification of inputs into signals or noise. Crucially, we found that subliminal inputs influenced false alarm rates only on blocks where the to-be-detected stimuli were present, and not on pre-test control blocks where they were absent. Participants appeared to adjust their perceptual criterion according to a statistical distribution of stimuli in the current context, with the presence of supraliminal stimuli having an important role in the criterion-setting process. These findings clarify the cognitive mechanisms that reserve conscious perception for salient and important signals.

Effects of Subliminal Stimulation on Imagery and Discrimination

In two separate investigations ( Ns = 13, 24), Ss drew spontaneously arising images after exposure of a subliminal visual stimulus. They then tried to discriminate the stimulus when it was again exposed subliminally. While the stimuli exerted a marked effect on Ss' images, they failed to influence Ss' discriminatory ability. It was concluded that a stimulus too faint to be consciously perceived can nevertheless have a pronounced effect on another mode of conscious experience—in this case, imagery.

Unconscious Affective Responses to Food

Affective or hedonic responses to food are crucial for humans, both advantageously (e.g., enhancing survival) and disadvantageously (e.g., promoting overeating and lifestyle-related disease). Although previous psychological studies have reported evidence of unconscious cognitive and behavioral processing related to food, it remains unknown whether affective reactions to food can be triggered unconsciously and its relationship with daily eating behaviors. We investigated these issues by using the subliminal affective priming paradigm. Photographs of food or corresponding mosaic images were presented in the peripheral visual field for 33 ms. Target photos of faces with emotionally neutral expressions were then presented, and participants rated their preferences for the faces. Eating behaviors were also assessed using questionnaires. The food images, relative to the mosaics, increased participants’ preference for subsequent target faces. Furthermore, the difference in the preference induced by food versus mosaic images was positively correlated with the tendency to engage in external eating. These results suggest that unconscious affective reactions are elicited by the sight of food and that these responses contribute to daily eating behaviors related to overeating.

Deliver us from Evil: The Effects of Mortality Salience and Reminders of 9/11 on Support for President George W. Bush

According to terror management theory, heightened concerns about mortality should intensify the appeal of charismatic leaders. To assess this idea, we investigated how thoughts about death and the 9/11 terrorist attacks influence Americans’ attitudes toward current U.S. President George W. Bush. Study 1 found that reminding people of their own mortality (mortality salience) increased support for Bush and his counterterrorism policies. Study 2 demonstrated that subliminal exposure to 9/11-related stimuli brought death-related thoughts closer to consciousness. Study 3 showed that reminders of both mortality and 9/11 increased support for Bush. In Study 4, mortality salience led participants to become more favorable toward Bush and voting for him in the upcoming election but less favorable toward Presidential candidate John Kerry and voting for him. Discussion focused on the role of terror management processes in allegiance to charismatic leaders and political decision making.

The Nonconscious Influence of Religious Symbols in Motivated Performance Situations

Anthropological, sociological, and psychological theories suggest that religious symbols should influence motivational processes during performance of goal-relevant tasks. In two experiments, positive and negative religious (Christian) symbols were presented outside of participants’ conscious awareness. These symbols influenced cardiovascular responses consistent with challenge and threat states during a subsequent speech task, particularly when the speech topic concerned participants’ mortality, and only for Christian participants; similar images lacking Christian meaning were not influential. Results suggested that these effects were due to the learned meaning of the symbols and point to the importance of religion as a coping resource.

When Less Is More: The Consequences of Affective Primacy for Subliminal Priming Effects

This research investigates the consequences of the notion that one can distinguish early-evaluative (when exposure is short) and late-descriptive reactions (when exposure is long) to subliminally primed trait concepts. In three studies, it was found that the evaluative effects instigated by short exposure to primed concepts were bigger than the evaluative + descriptive effects instigated by long exposure: Less is more. Only when exposure was short, target interpretations were accompanied by evaluative inferences (Studies 1 and 3). Similarly, only when exposure was short, descriptively inapplicable trait primes affected the interpretation of an ambiguous target (Studies 2 and 3).

The Correspondence between Attachment to Parents and God: Three Experiments Using Subliminal Separation Cues

Attachment theoretical studies have increased our understanding of the socioemotional foundations for religious development. However, because these studies have been correlational and based on self-reports, they are vulnerable to concerns of self-presentation bias and lack of basis for causal inference. Three subliminal stimulation experiments were therefore performed, where activation of the attachment system was attempted by way of unconsciously administered separation stimuli. In Experiments 1 and 3 (N = 29 and 89), the separation stimulus alluded to God, and in Experiment 2 (N = 47), it alluded to mother. Responses were moderated by perceived attachment history with parents in all experiments. Participants with secure histories increased in religious attachment behaviors, whereas those with insecure histories decreased following attachment system activation compared with control stimulation. There also were suggestions of experimental group increase in proximity seeking in relation to God. The main conclusion supports correspondence between internal working models of parents and God.

Prior Source Exposure and Persuasion: Further Evidence for Misattributional Processes

To assess the persuasive impact of prior source exposure, two studies paired persuasive messages with a source to whom participants had previously been exposed subliminally, explicitly, or not at all. In Experiment 2, participants' attention also was drawn to information that potentially undermined the implications of any reaction to re-exposure. Compared to no exposure, prior subliminal exposure increased the source's persuasiveness, an effect not mediated by source liking. Explicit exposure increased source persuasiveness to the extent that the source was liked more and only absent a recall cue. Results favored misattributional accounts of prior exposure effects.

Partial Awareness Creates the “Illusion” of Subliminal Semantic Priming

We argue that the lack of consensus regarding the existence of subliminal semantic processing arises from not taking into account the fact that linguistic stimuli are represented across several processing levels (features, letters, word form) that can independently reach or not reach awareness. Using masked words, we constructed conditions in which participants were aware of some letters or fragments of a word, while remaining unaware of the whole word. Three experiments using the Stroop priming paradigm show that when the stimulus set is reduced and participants are encouraged to guess the identity of the prime, such partially perceived stimuli can nonetheless give rise to “semantic” processing. We provide evidence that this effect is due to illusory reconstruction of the incompletely perceived stimulus, followed by usual semantic processing of the result. We conclude that previously reported unconscious Stroop priming is in fact a conscious effect, but applied to a perceptual illusion.

Of Two Minds

Because different processes underlie implicit and explicit attitudes, we hypothesized that they are differentially sensitive to different kinds of information. We measured implicit and explicit attitudes over time, as different types of attitude-relevant information about a single attitude object were presented. As expected, explicit attitudes formed and changed in response to the valence of consciously accessible, verbally presented behavioral information about the target. In contrast, implicit attitudes formed and changed in response to the valence of subliminally presented primes, reflecting the progressive accretion of attitude object-evaluation pairings. As a consequence, when subliminal primes and behavioral information were of opposite valence, people formed implicit and explicit attitudes of conflicting valence.

A general magnitude system in human adults: Evidence from a subliminal priming paradigm

Despite general agreement that number and other magnitudes share analog format, there is disagreement about the extent to which representations of numerical and non-numerical magnitude recruit common cognitive and neural resources. Cross-dimensional interactions between number and other magnitudes on Stroop-like tasks have been taken as evidence for integration across magnitudes, but such effects are subject to alternative interpretations that allow for differentiated representations. Here we use a subliminal priming paradigm to test for interactions between different magnitudes (number and area) when one magnitude is not consciously detectable. Across two experiments, we first provide evidence for the feasibility of this paradigm by demonstrating that transfer occurs within the dimension of number; that is, symbolic numerals (Arabic digits) that were subliminally primed affected judgments of non-symbolic numerosities in target displays. Crucially, we also found transfer across magnitudes-from subliminally primed numerals to target displays of cumulative surface area whether participants made an ordinal judgment (i.e., "which array is larger in area?") or judged whether two arrays were the same or different in area. These findings suggest that representations of number and area are not fully differentiated. Moreover, they provide unique support for a general magnitude system that includes direct connections, or overlap, between the neural codes for numerical and non-numerical magnitudes.

The innate alarm circuit in post-traumatic stress disorder: Conscious and subconscious processing of fear- and trauma-related cues

Fast defensive responses to salient threatening stimuli are an important clinical feature of post-traumatic stress disorder (PTSD). We investigated the neural correlates of subliminal and supraliminal processing of fearful faces and individualized trauma-related words in individuals with PTSD (n=26) compared with healthy controls (n=20) using functional magnetic resonance imaging. Increased activity in the right cerebellum and the posterior cingulum was observed in individuals with PTSD during subliminal processing of trauma-related words, whereas increased activity of the basal forebrain was found within the PTSD group when processing supraliminal trauma-related words. Moreover, significant positive correlations were found between re-experiencing symptoms and response within the amygdala, and between hyper-arousal symptoms and response within the periaqueductal gray matter, during subliminal processing of trauma-related words and during supraliminal processing of fearful faces, respectively. These findings further our understanding of rapid threat processing and defensive responses, highlighting the role of the cerebellum and periaqueductal gray matter as part of an 'innate alarm system' in PTSD.

Effect of Subliminal Lexical Priming on the Subjective Perception of Images: A Machine Learning Approach

The purpose of the study is to examine the effect of subliminal priming in terms of the perception of images influenced by words with positive, negative, and neutral emotional content, through electroencephalograms (EEGs). Participants were instructed to rate how much they like the stimuli images, on a 7-point Likert scale, after being subliminally exposed to masked lexical prime words that exhibit positive, negative, and neutral connotations with respect to the images. Simultaneously, the EEGs were recorded. Statistical tests such as repeated measures ANOVAs and two-tailed paired-samples t-tests were performed to measure significant differences in the likability ratings among the three prime affect types; the results showed a strong shift in the likeness judgment for the images in the positively primed condition compared to the other two. The acquired EEGs were examined to assess the difference in brain activity associated with the three different conditions. The consistent results obtained confirmed the overall priming effect on participants' explicit ratings. In addition, machine learning algorithms such as support vector machines (SVMs), and AdaBoost classifiers were applied to infer the prime affect type from the ERPs. The highest classification rates of 95.0% and 70.0% obtained respectively for average-trial binary classifier and average-trial multi-class further emphasize that the ERPs encode information about the different kinds of primes.

[Does Emotional Context Affect Subliminal and Supraliminal Priming?]

OBJECTIVE

Emotions are complex psychophysiological changes experienced during the interactions of internal and external processes. The stimuli that have emotional value have processing efficiency both in encoding and retrieval processes with respect to the neutral stimuli. Processing advantage is present also for implicit memory. Priming effect does not require conscious recollection and leads to changes in responding due to previous exposure to the stimulus. In this study, it was aimed to investigate the effect of presentation type and different emotional contexts on the priming.

METHOD

Sixty-volunteered-university-students were (Female: n=40, X age=19.03±1.23; Male: n=20, X age=19.70±1.92) randomly assigned to the experimental conditions. Presentation type (Subliminal and Supraliminal) was between subject and Emotional Context (pleasant, neutral, and unpleasant pictures) was within subject independent variables. Dependent variables were Word Stem Completion score and completion latencies.

RESULTS

Unpleasant emotional context had more capacity to create priming effect than the other emotional contexts. Both Subliminal and Supraliminal conditions favored the priming. Controversially to the transfer appropriate processing approach, the priming effect that was produced by supraliminal condition significantly higher than the priming created by the subliminal condition.

CONCLUSION

Unpleasant picture context produced more priming due to reason that evolutionarily important, i.e. thread-related, stimuli have processing priority and they capture the attention, utilize other cognitive resources easily. Even in priming, that is a phenomenon based heavily on data driven processes, concept driven processes are also effectual as indicated by levels-of-processing approach.

Unconscious Desire: The Affective and Motivational Aspects of Subliminal Sexual Priming

Sexual arousal is thought to be the result of the processing of sexual cues at two levels: conscious and unconscious. Whereas numerous studies have examined the affective and motivational responses to supraliminal (consciously processed) sexual cues, much less is known regarding the responses to subliminal (processed outside of one's awareness) sexual cues. Five studies examined responses to subliminal sexual cues. Studies 1–3 demonstrated increases in adults' positive affect following exposure to subliminal sexual cues compared to control cues. Study 4 demonstrated that the positive affect resulting from exposure to subliminal sexual cues increased motivation to further engage in a neutral task. Study 5 provided evidence suggesting that the affect and motivation found in Studies 1–4 were associated with motivation to engage in sex specifically, rather than a general approach motivation. The implications of these findings for the processing of subliminal sexual cues and for human sexuality are discussed.

Cognitive neuroscience: integration of sight and sound outside of awareness?

A recent study found that auditory and visual information can be integrated even when you are completely unaware of hearing or seeing the paired stimuli--but only if you have received prior, conscious exposure to the paired stimuli.

Early sensory processing in right hemispheric stroke patients with and without extinction

While extinction is most commonly viewed as an attentional disorder and not as a consequence of a failure to process contralesional sensory information, it has been speculated that early sensory processing of contralesional targets in extinction patients might not be fully normal. We used a masked visuo-motor response priming paradigm to study the influence of both contralesional and ipsilesional peripheral subliminal prime stimuli on central target performance, allowing us to compare the strength of the early sensory processing associated with these prime stimuli between right brain damaged patients with and without extinction as well as healthy elderly subjects. We found that the effect of an informative subliminal prime in the left contralesional visual field on central target performance was significantly reduced in both right brain damaged patients with and without extinction. The results suggest that a low-level early sensory deterioration of the neural representation for contralesional prime stimuli is a general consequence of right hemispheric brain damage unrelated to the presence or absence of extinction. This suggests that the presence of a spatial bias against contralesional information is not sufficient to elicit extinction. For extinction to occur, this spatial bias might need to be accompanied by a pathological (non-directional) reduction of attentional capacity.

[Unconscious Acoustical Stimuli Effects on Event-related Potentials in Humans]

Unconscious perception essentially affects human behavior. The main results in this area obtained in experiments with visual stimuli. However, the acoustical stimuli play not less important role in behavior. The main idea of this paper is the electroencephalographic investigation of unconscious acoustical stimulation effects on electro-physiological activity of the brain. For this purpose, the event-related potentials were acquired under unconscious stimulus priming paradigm. The one syllable, three letter length, Russian words and pseudo-words with single letter substitution were used as primes and targets. As a result, we find out that repetition and alternative priming similarly affects the event-related potential's component with 200 ms latency after target application in frontal parietal and temporal areas. Under alternative priming the direction of potential amplitude modification nearby 400 ms was altered for word and semi-word targets. Alternative priming reliably increase ERP's amplitude in 400 ms locality with pseudo-word targets and decrease it under word targets. Taking into account, that all participants were unable to distinguish the applied prime stimuli, we can assume that the event-related potential changes evoked by unconscious perception of acoustical stimuli. The ERP amplitude dynamics revealed in current investigation demonstrate the opportunity of subliminal acoustical stimuli to modulate the electrical activity evoked by verbal acoustical stimulation.

Influence of positive subliminal and supraliminal affective cues on goal pursuit in schizophrenia

Goal pursuit is known to be impaired in schizophrenia, but nothing much is known in these patients about unconscious affective processes underlying goal pursuit. Evidence suggests that in healthy individuals positive subliminal cues are taken as a signal that goal pursuit is easy and therefore reduce the effort that is mobilized for goal attainment. Patients with schizophrenia and healthy controls were instructed that a long run of successive correct responses in a visual attention task would entitle them to a reward (the goal to attain). Affective pictures were displayed supraliminally or subliminally during each run and electrophysiological activity was recorded. Patients self-assessed the emotional content of the pictures correctly. However, differences between patients and controls emerged during the goal pursuit task. Healthy controls mobilized less effort for the positive than the neutral subliminal pictures, as suggested by increased error rates and the weaker contingent negative variation (CNV). For the patients, no influence of positive subliminal pictures was found on performance and on the CNV. Similarly the influence of positive pictures was absent or abnormal on components which are usually impaired in patients (fronto-central P2 and N2). In contrast, positive pictures influenced normally the parieto-occipital N2, related to a component of visual attention which has been proposed to be preserved in schizophrenia. The present study indicates the difficulties of patients to modulate effort mobilization during goal pursuit in the presence of positive subliminal cues. The results question the role of cognitive deficits on affective influences.

Effects of cognitive-behavioral therapy on brain responses to subliminal and supraliminal threat and their functional significance in specific phobia

BACKGROUND

Neurocircuitry models of anxiety disorders suggest dysregulated mechanisms encompassing both automatic and elaborate threat processing. However, the extent to which these processes might be differentially modified by psychotherapy and the neural basis of such changes are unknown. We examined the effects of cognitive-behavioral therapy (CBT) in patients with anxiety disorder on brain responses to subliminal and supraliminal threat.

METHODS

3-Tesla functional magnetic resonance imaging was used to assess neural responses to disorder-related stimuli, presented during two backward-masking conditions employed to manipulate stimulus awareness. In 28 spider-phobic patients randomly assigned to a therapy group or a waiting-list control group scanning was performed before and after completing CBT or a waiting period. Scanning was performed one time in 16 healthy control subjects. Self-report and behavioral measures were used to relate CBT-mediated brain activation changes with symptom improvement.

RESULTS

Untreated patients demonstrated abnormal hyperactivation in the amygdala, fusiform gyrus, insula, anterior cingulate cortex, and dorsomedial prefrontal cortex. Successful CBT was reflected in an overall downregulation in these fear circuitry structures, especially in the right amygdala and anterior cingulate cortex, with reductions in amygdala responsiveness associated with self-reported symptom improvement. However, subliminal threat induced a pattern of right-lateralized hyperactivation in the amygdala and fusiform gyrus that was subject to intersession habituation across groups without showing significant sensitivity to CBT.

CONCLUSIONS

These results challenge prevailing models that emphasize a role for amygdala automaticity in the maintenance of anxiety. Our results suggest CBT-related changes in neural activation associated with fear responses to consciously perceived threat.

Automatic evaluations and exercise setting preference in frequent exercisers

The goals of this study were to test whether exercise-related stimuli can elicit automatic evaluative responses and whether automatic evaluations reflect exercise setting preference in highly active exercisers. An adapted version of the Affect Misattribution Procedure was employed. Seventy-two highly active exercisers (26 years ± 9.03; 43% female) were subliminally primed (7 ms) with pictures depicting typical fitness center scenarios or gray rectangles (control primes). After each prime, participants consciously evaluated the "pleasantness" of a Chinese symbol. Controlled evaluations were measured with a questionnaire and were more positive in participants who regularly visited fitness centers than in those who reported avoiding this exercise setting. Only center exercisers gave automatic positive evaluations of the fitness center setting (partial eta squared = .08). It is proposed that a subliminal Affect Misattribution Procedure paradigm can elicit automatic evaluations to exercising and that, in highly active exercisers, these evaluations play a role in decisions about the exercise setting rather than the amounts of physical exercise. Findings are interpreted in terms of a dual systems theory of social information processing and behavior.

Priming effects on the perceived grouping of ambiguous dot patterns

For ambiguous stimuli, complex dynamics guide processes of perceptual grouping. Previous studies have suggested two opposing effects on grouping that are produced by the preliminary stimulus state: one that enhances grouping towards the existing structure, and another that opposes this structure. To examine effects of the preliminary state on grouping directly, measurements were made of perceived grouping of dot patterns that followed a visual prime. Three stimuli were presented in sequence: prime, target, and mask. Targets were composed of an evenly spaced dot grid in which grouping was established by similarity in luminance. Subjects indicated the dominant perceived grouping. The prime either corresponded to or opposed the prevailing organization of the target. Contrary to the hypothesis, solid-line primes biased grouping away from the structure of the prime, even when the prevailing organization of dot patterns strongly favored the primes' structure. This effect occurred, although to a lesser extent, when primes did not occupy the same location of targets, but were presented in a marginal area surrounding the grid. Priming effects did not occur for primes constructed of dot patterns. Effects found here may be attributed to a forward masking effect by primes, which more effectively disrupts grouping of patterns matched to the prime. Effects may also be attributed to a type of pattern contrast, in which a grouped pattern dissimilar to primes gains salience. For the pattern contrast model, the partial activation of multiple grouped configurations is compared to the pattern of the solid-line primes.

Fear conditioning to subliminal fear relevant and non fear relevant stimuli

A growing body of evidence suggests that conscious visual awareness is not a prerequisite for human fear learning. For instance, humans can learn to be fearful of subliminal fear relevant images--images depicting stimuli thought to have been fear relevant in our evolutionary context, such as snakes, spiders, and angry human faces. Such stimuli could have a privileged status in relation to manipulations used to suppress usually salient images from awareness, possibly due to the existence of a designated sub-cortical 'fear module'. Here we assess this proposition, and find it wanting. We use binocular masking to suppress awareness of images of snakes and wallabies (particularly cute, non-threatening marsupials). We find that subliminal presentations of both classes of image can induce differential fear conditioning. These data show that learning, as indexed by fear conditioning, is neither contingent on conscious visual awareness nor on subliminal conditional stimuli being fear relevant.

Priming mortality salience: supraliminal, subliminal and "double-death" priming techniques

The study examined whether successively presented subliminal and supraliminal morality salience primes ("double death" prime) would have a stronger influence on death thought accessibility than subliminal or supraliminal primes alone. A between-subjects 2 (subliminal prime/control) × 2 (supraliminal prime/control) design was used. The supraliminal prime prompted participants to answer questions about death. For the subliminal prime, the word death was presented outside of awareness. Both priming techniques differed significantly from a control in ability to elicit mortality salience. There was an interactive influence of both primes. Implications for unconscious neutral networks relating to death are discussed.

A model of subjective report and objective discrimination as categorical decisions in a vast representational space

Subliminal perception studies have shown that one can objectively discriminate a stimulus without subjectively perceiving it. We show how a minimalist framework based on Signal Detection Theory and Bayesian inference can account for this dissociation, by describing subjective and objective tasks with similar decision-theoretic mechanisms. Each of these tasks relies on distinct response classes, and therefore distinct priors and decision boundaries. As a result, they may reach different conclusions. By formalizing, within the same framework, forced-choice discrimination responses, subjective visibility reports and confidence ratings, we show that this decision model suffices to account for several classical characteristics of conscious and unconscious perception. Furthermore, the model provides a set of original predictions on the nonlinear profiles of discrimination performance obtained at various levels of visibility. We successfully test one such prediction in a novel experiment: when varying continuously the degree of perceptual ambiguity between two visual symbols presented at perceptual threshold, identification performance varies quasi-linearly when the stimulus is unseen and in an 'all-or-none' manner when it is seen. The present model highlights how conscious and non-conscious decisions may correspond to distinct categorizations of the same stimulus encoded by a high-dimensional neuronal population vector.

Pupil response and the subliminal mere exposure effect

The subliminal mere exposure effect (SMEE) is the phenomenon wherein people tend to prefer patterns they have repeatedly observed without consciously identifying them. One popular explanation for the SMEE is that perceptual fluency within exposed patterns is misattributed to a feeling of preference for those patterns. Assuming that perceptual fluency is negatively correlated with the amount of mental effort needed to analyze perceptual aspects of incoming stimuli, pupil diameter should associate with SMEE strength since the former is known to reflect mental effort. To examine this hypothesis, we measured participants' pupil diameter during exposure to subthreshold stimuli. Following exposure, a preference test was administered. Average pupil diameter throughout exposure was smaller when the SMEE was induced than when the SMEE was not induced. This supports the hypothesis that increasing perceptual fluency during mere exposure modulates autonomic nervous responses, such as pupil diameter, and eventually leads to preference.

Robust single trial identification of conscious percepts triggered by sensory events of variable saliency

The neural correlates of visual awareness are elusive because of its fleeting nature. Here we have addressed this issue by using single trial statistical "brain reading" of neurophysiological event related (ERP) signatures of conscious perception of visual attributes with different levels of saliency. Behavioral reports were taken at every trial in 4 experiments addressing conscious access to color, luminance, and local phase offset cues. We found that single trial neurophysiological signatures of target presence can be observed around 300 ms at central parietal sites. Such signatures are significantly related with conscious perception, and their probability is related to sensory saliency levels. These findings identify a general neural correlate of conscious perception at the single trial level, since conscious perception can be decoded as such independently of stimulus salience and fluctuations of threshold levels. This approach can be generalized to successfully detect target presence in other individuals.

The implications of conceptual critiques and empirical research on unconscious processes for psychoanalytic theory

The paper examines the implications of conceptual critiques and empirical research on psychoanalytic formulations of unconscious processes. Different conceptions of unconscious processes and states are discussed: as markers for brain states, as unformulated and not-spelled-out fleeting experiences, and as implicit knowledge. The author notes and discusses the interpersonal and interactional aspects of unconscious processes in classical theory as well as in contemporary formulations. Representative examples of empirical research on unconscious processes are presented and their implications for psychoanalytic conceptions are examined. The author then discusses the conception of unconscious processes that emerges in view of conceptual critiques, empirical research findings, and clinical phenomena. Finally, the emphasis of both early and late Freudian theory on integration of various aspects of the personality rather than (or at least in addition to) on conscious versus unconscious is noted, and various ways of understanding what it means to make the unconscious conscious are discussed.