We addressed the questions whether stimuli presented below the threshold of verbal awareness are nevertheless perceived and whether there are perceptual differences between the two cerebral hemispheres. Pictures of line drawn objects and animals were subliminally presented to each visual half-field for subsequent identification in a form as fragmented as possible. The performance of 40 healthy subjects was compared to that of 63 controls. Whereas identification performance after blank presentation in the experimental group did not differ from that of (...) controls, identification in a significantly more fragmented form was achieved after the presentation of the complete picture. This effect, however, occurred only after subliminal stimulation in the left visual field, i.e., of the right hemisphere. Our results show that pictures presented below the threshold of verbal awareness can be perceived, and that only the right hemisphere can perceive them and make use of the perception. It remains an open question whether this kind of hemispheric specialization represents a right hemisphere dominance for subliminal perception or reflects an inability of the left hemisphere to access and behaviorally use unaware percepts via fragmented picture identification, for which a right hemisphere advantage is known. (shrink)

This study investigated the effect of unconscious processing on creative problem solving (CPS) by combining a revised priming paradigm that manipulated the content of unconscious processing together with remote association tests (RAT). In the real world, most CPS is facilitated by unconscious information processing after a problem is represented. However, most previous studies have focused on priming subthreshold stimuli before the problem presentation, with few exploring unconscious priming after the problem is presented, even though different prime timings might involve (...) distinct processing mechanisms. Therefore, Experiment 1 compared the unconscious priming effects of presenting the prime prior to the target (Before-T) versus during target solving (During-T). The RAT difficulty and type of priming material were also manipulated. The results of Experiment 1 revealed a significant difference in the priming effects of prime timing with the During-T group benefiting more from subliminal stimuli than the Before-T group. Experiment 2 further strengthened the justifications for the hypotheses regarding the influence of word versus picture priming in the during-T condition. Overall, this study found a clear dissociable contribution of unconscious processing to CPS, and the facilitation effect was optimised by prime timing, the prime material, and RAT difficulty. (shrink)

Evaluative learning refers to the change in the affective evaluation of a previously neutral stimulus that occurs after the stimulus has been associated with a second, positive or negative, affective stimulus . Four experiments are reported in which the AS was presented very briefly. Significant evaluative learning was observed in participants who did not notice the presentation of the affective stimuli or could not discriminate between the briefly presented positive and negative ASi when asked to do so . In (...) two other experiments , no significant learning effect was obtained. A meta-analysis performed on the present and previously reported results gave evidence for a small, though statistically reliable evaluative learning effect when ASi are presented “subliminally.” This finding supports the hypothesis that evaluative associations can be learned implicitly. (shrink)

Understanding the processing of sexual stimuli has become a significant part of research on human sexuality. In addition to individual characteristics, empirical studies have shown that cultural factors play an important role in sexual stimuli processing. The attitudes toward sex have been reported to be more conservative in East Asian societies as compared to western countries, and significantly more sexual difficulties are observed among East Asian people. However, stimulus materials, which potentially facilitate human sexuality research on native East (...) Asian people, are relatively not satisfactory. Erotic stimuli depicting East Asian figures are limited in the existing picture datasets. To address this issue, we present a collection of 237 erotic and 108 control pictures, accompanied by self-reported ratings of sexual arousal, pleasantness, and sexual attractiveness for opposite-sex erotic stimuli by heterosexual males and females. This collection is divided into six categories, depending on their contents: dressed males, semi-nude males, nude males, dressed females, semi-nude females, and nude females. We showed gender differences in sexual arousal, pleasantness, and sexual attractiveness ratings in response to opposite-sex erotic pictures. Males reported the highest levels of sexual arousal, pleasantness, and sexual attractiveness for nude female pictures, whereas females reported the highest levels of sexual arousal, pleasantness, and sexual attractiveness for semi-nude male pictures. The erotic picture dataset may provide a useful resource of erotic stimuli that can be used as stimulus materials in experimental research on sexual function in East Asians. (shrink)

Prefrontal cortex is dysregulated in women with restricting anorexia nervosa . It is not known whether appetitive non-conscious stimuli bias cognitive responses in those with RAN. Thirteen women with RAN and 20 healthy controls completed a dorsolateral PFC working memory task and an anterior cingulate cortex conflict task, while masked subliminal food, aversive and neutral images were presented. During the DLPFC task, accuracy was higher in the RAN compared to the HC group, but superior performance was compromised when (...) subliminal food stimuli were presented: errors positively correlated with self-reported trait anxiety in the RAN group. These effects were not observed in the ACC task. Appetitive activation is intact and anxiogenic in women with RAN, and non-consciously interacts with working memory processes associated with the DLPFC. This interaction mechanism may underlie cognitive inhibition of appetitive processes that are anxiety inducing, in people with AN. (shrink)

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. (shrink)

Research on perception without awareness has provoked strong emotional responses from individuals within and outside the scientific community, due in part to the perceived potential for abuse of subliminal techniques. In this paper, four basic issues regarding the use of subliminal techniques for propaganda purposes are discussed: whether exposure to subliminal stimuli can produce significant, predictable changes in affect, cognition and behavior; whether these effects are robust and powerful enough to make the use of subliminal (...) techniques for propaganda purposes feasible; whether the effects of subliminal stimulation are stable over time; and whether subliminal influences can be resisted by unwilling subjects. Research suggests that exposure to simple drive-or affect-related subliminal stimuli can produce ecologically significant, temporally stable changes in attitudes and behavior, and therefore may have potential for use as propaganda tools. Implications of these findings for our understanding of the mechanisms underlying subliminal perception are discussed. Technical problems which would need to be addressed before subliminal propaganda techniques could be employed are also discussed. Ethical issues raised by the use of covert attitude and behavior manipulation techniques are addressed. (shrink)

Unconscious processing of stimuli with emotional content can bias affective judgments. Is this subliminal affective priming merely a transient phenomenon manifested in fleeting perceptual changes, or are long-lasting effects also induced? To address this question, we investigated memory for surprise faces 24 h after they had been shown with 30-ms fearful, happy, or neutral faces. Surprise faces subliminally primed by happy faces were initially rated as more positive, and were later remembered better, than those primed by fearful or (...) neutral faces. Participants likely to have processed primes supraliminally did not respond differentially as a function of expression. These results converge with findings showing memory advantages with happy expressions, though here the expressions were displayed on the face of a different person, perceived subliminally, and not present at test. We conclude that behavioral biases induced by masked emotional expressions are not ephemeral, but rather can last at least 24 h. (shrink)

In a task requiring speeded bidirectional responses to arrow symbols , “free choice” responses to interspersed bidirectional stimuli are influenced by masked directional primes . By varying stimulus–response compatibility, we tested whether this priming effect is mediated by the conscious instructional set, or instead by pre-existing directional associations to the symbols. In two experiments, one group of participants was instructed to respond with the hand consistent with the implied direction of the arrow symbols, while another group was instructed to (...) make the spatially opposite responses. Both groups showed priming of “free choice” responses. However, such priming was always biased according to the instructional set rather than pre-existing associations. Subliminal priming of “free choice” responses therefore depends on conscious task goals. (shrink)

Four experiments were conducted to evaluate explanations of picture superiority effects previously found for several tasks. In a process dissociation procedure with word stem completion, picture fragment completion, and category production tasks, conscious and automatic memory processes were compared for studied pictures and words with an independent retrieval model and a generate-source model. The predictions of a transfer appropriate processing account of picture superiority were tested and validated in “process pure” latent measures of conscious and unconscious, or (...) automatic and source, memory processes. Results from both model fits verified that pictures had a conceptual processing advantage over words for all tasks. The effects of perceptual compatibility depended on task type, with pictorial tasks favoring pictures and linguistic tasks favoring words. Results show support for an explanation of the picture superiority effect that involves an interaction of encoding and retrieval processes. (shrink)

The present ERP study investigated effects of subliminal emotional words on preference judgments about subsequent visual target stimuli . Each target was preceded by a masked 17-ms emotional adjective. Four classes of prime words were distinguished according to the combinations of positive/negative valence and high/low arousal. Targets were liked significantly more after positive-arousing primes , relative to negative-arousing , positive-nonarousing , and negative-nonarousing primes . In the target ERP, amplitude of right-hemisphere positive slow wave was increased after positive-arousing (...) compared to negative-arousing primes. Evaluative priming effects on judgments and ERPs were more pronounced in high state-anxious participants. The results suggest that there is indeed affective/semantic processing of unconscious words, evaluative priming operates relatively late during target processing, to be effective, prime words need to score high on the arousal dimension, and individual differences in state anxiety modulate the susceptibility to subliminal evaluative priming. (shrink)

One problem of interpreting research on subconscious processing is the possibility that participants are weakly conscious of the stimuli. Here, we compared the fMRI BOLD response in healthy adults to clearly visible single letters with the response to letters presented in the absence of any behavioural evidence of visibility . No letter catch trials served as a control condition. Forced-choice responses did not differ from chance when letter-to-background contrast was low, whereas they were almost 100% correct when contrast was (...) high. A comparison of fMRI BOLD signals for supraliminal and subliminal letters with the control trials revealed a signal increase in left BA 37 . Comparison of supraliminal with subliminal letters showed a significant increase in the right inferior frontal gyrus . Finally, a comparison of subliminal with supraliminal letters showed increases in the left middle temporal gyrus and the right extrastriate cortex. (shrink)

Primary and secondary processes are the foundational axes of the Freudian mental apparatus: one horizontally as a tendency to associate, the primary process, and one vertically as the ability for perspective taking, the secondary process. Primary process mentation is not only supposed to be dominant in the unconscious but also, for example, in dreams. The present study tests the hypothesis that the mental activity during REM-sleep has more characteristics of the primary process, while during non-REM-sleep more secondary process operations take (...) place. Because the solving of a rebus requires the ability to non-contexually condensate the literal reading of single stimuli into a new one, rebus solving is a primary process operation by excellence. In a replication of the dream-rebus study of Shevrin and Fisher (1967), a rebus, which consisted of an image of a comb (German: “Kamm”) and an image of a raft (German: “Floß”), resulting in the German rebus word “kampflos” (Engl.: without a struggle), was flashed subliminally (at 1 ms) to 20 participants before going to sleep. Upon consecutive awakenings participants were asked for a dream report, free associations and an image description. Based on objective association norms, there were significantly more conceptual associations referring to Kamm and Floß indexing secondary process mentation when subjects were awakened from non-REM sleep as compared to REM-awakenings. There were not significantly more rebus associations referring to kampflos indexing primary process mentation when awakened from REM-sleep as compared to non-REM awakenings. However, when the associations were scored on the basis of each subject’s individual norms, there was a rebus effect with more idiosyncratic rebus associations in awakenings after REM than after non-REM-sleep. Our results support the general idea that REM-sleep is characterized by primary process thinking, while non-REM-sleep mentation follows the rules of the secondary process. (shrink)

We conducted two experiments using naturalistic scene stimuli to test the resource theory and mindlessness theory of sustained attention. In experiment 1, 28 participants completed a traditional formatted vigilance task consisting of non-repeating forest or urban picture stimuli as target stimuli. Participants filled out pre- and post-task assessments of arousal and conscious thoughts. There was still a vigilance decrement, despite non-repetitive, natural target stimuli. Participants found the task demanding and were actively engaged in the task. (...) In experiment 2, 25 participants completed a Sustained Attention to Response Task using the stimuli from experiment 1. Participants performed significantly worse on this SART than either brain injury patients or controls performing equivalent numeric stimuli SARTs have in previous studies. Participants thought the task was demanding and they were actively engaged with the task. Overall, the results of both studies support a resource theory of sustained attention lapses, not a mindlessness theory. (shrink)

An important approach to understand how the brain gives rise to consciousness is to probe the depth of unconscious processing, thus to define the key features that cause conscious awareness. Here, we investigate the possibility for subliminal stimuli to shape the context for unconscious processing. Context effects have generally been assumed to require consciousness. In the present experiment, unconscious context processing was investigated by looking at the impact of the context on the response activation elicited by a (...) class='Hi'>subliminal prime. We compared the effects of the same subliminal prime on target processing when the prime was embedded in different unconscious contexts. Results showed that the same prime can evoke opposite responses depending on the unconscious context in which it is presented. Taken together, the results of this study show that context effects can be unconscious. (shrink)

Choice reaction times to visual stimuli may be influenced by preceding subliminal stimuli . Some authors reported a straight priming effect i.e., responses were faster when primes and targets called for the same response than when they called for different responses. Others found the reversed pattern of results. Eimer and Schlaghecken [Eimer, M. & Schlaghecken, F. . Links between conscious awareness and response inhibition: evidence from masked priming. Psychonomic Bulletin & Review, 9, 514–520.] showed recently that straight (...) priming occurs whenever a prime is not efficiently masked thereby the information provided by the prime is accessible for consciousness. In the present study, a hypothesis is tested that straight priming is due to mediation of consciousness. To test this hypothesis, prime validity was manipulated. We showed that even when no mask was used so that participants could fully and consciously perceive the prime and participants were informed that primes were mostly invalid, for the short prime–target ISI interval straight priming occurred. The priming was inverse when the ISI was 800 ms. This indicates that participants were able to use the information provided by the prime to prepare the response opposite to that cued by the prime but only if the time between the prime and the target was long enough. (shrink)

Four experiments demonstrate category congruency priming by subliminal prime words that were never seen as targets in a valence-classification task and a gender-classification task . In Experiment 1, overlap in terms of word fragments of one or more letters between primes and targets of different valences was larger than between primes and targets of the same valence. In Experiments 2 and 3, the sets of prime words and target words were completely disjoint in terms of used letters. In Experiment (...) 4, pictures served as targets. The observed subliminal priming effects for novel primes cannot be driven by partial analysis of primes at the word-fragment level; they suggest instead that primes were processed semantically as whole words contingent upon prime duration. (shrink)

Recently, priming effects of unconscious stimuli that were never presented as targets have been taken as evidence for the processing of the stimuli’s semantic categories. The present study explored the necessary conditions for a transfer of priming to novel primes. Stimuli were digits and letters which were presented in various viewer-related orientations . The transfer of priming to novel stimulus orientations and identities was remarkably limited: in Experiment 1, in which all conscious targets stood upright, no transfer (...) to unconscious primes in a non-target orientation was found. Experiment 2, in which primes were presented without masks, ruled out the possibility that primes were presented too short to allow congruency effects. In Experiments 3 and 4, in which all targets were presented upside down, priming transferred to upright stimuli with target identities but neither to horizontal stimuli nor to stimuli with novel identities. We suggest that whether a transfer of priming to unpracticed stimuli occurs or not depends on observers’ expectations of specific stimulus exemplars. (shrink)

The present study was designed to explore the performance costs of negative emotional stimuli in a vigilance task. Forty participants performed a vigilance task in two conditions: one with task-irrelevant negative-arousing pictures and one with task-irrelevant neutral pictures. In addition to performance, we measured subjective state and frontal cerebral activity with near infrared spectroscopy. Overall performance in the negative picture condition was lower than in the neutral picture condition and the negative picture condition had elevated levels (...) of energetic arousal, tense arousal and task-related thoughts. Moreover, there was a significant relationship between the impact of the negative pictures on tense arousal and task-related thoughts and the impact of the negative pictures on performance . These results provide support for indirect cost models of negative emotional stimuli on target detection performance. (shrink)

Many studies require standardized and replicable protocols composed of emotional stimuli. To this aim, several databases of emotional pictures are available. However, there are only few images directly depicting interpersonal violence, which is a specific emotion evocative stimulus for research on aggressive behavior or post-traumatic stress disorder. The objective of the current study is to provide a new set of standardized stimuli containing images depicting interpersonal situations. This will allow a sensitive assessment of a wide range of cognitions (...) linked to social interaction. To this aim, 240 participants rated the valence and arousal of 79 pictures collected from online sources in 2018. Results showed a distinctive pattern of valence and arousal regarding the picture content and specific associations between those two dimensions. Taken together, these results suggest a good reliability of the selected images. In conclusion, our study provides an open access set of recent pictures depicting interpersonal situations along with normative valence and arousal ratings, that are available for download from: https://osf.io/ak4m7/?view_only=None. (shrink)

Reading fiction for pleasurable is robustly correlated with improved cognitive attainment and other benefits. It is also in decline among young people in developed nations, in part because of competition from moving image fiction. We review existing research on the differences between reading/hearing verbal fiction and watching moving image fiction, as well as looking more broadly at research on image/text interactions and visual versus verbal processing. We conclude that verbal narrative generates more diverse responses than moving image narrative., We note (...) that reading and viewing narrative are different tasks, with different cognitive loads. Viewing moving image narrative mostly involves visual processing with some working memory engagement, whereas reading narrative involves verbal processing, visual imagery and personal memory (Xu et al 2005). but Attempts to compare the two by creating suggest that existing research is flawed by attempts to create equivalent stimuli and task demands face a number of challenges, and we discuss these difficulties in comparative approaches. We then investigate the possibility of identifying lower level processing mechanisms that might distinguish cognition of the two media, and propose a focus on internal scene construction and on working memory as foci for future research. Although many of the sources we draw on are focussed on English speaking participants in European or North American settings, we also cover material relating to speakers of Dutch, German, Hebrew and Japanese in their respective countries, and studies of a remote Turkish mountain community. (shrink)

Contrary to Perruchet & Vinter's self-organizing consciousness (SOC) model, subliminal mere exposure (SME) research indicates that stimuli perceived without awareness produce robust effects. Moreover, SME effects are significantly stronger than mere exposure effects produced by clearly recognized stimuli. The SOC model must be revised to accommodate findings from studies that use affect-based outcome measures.

Awareness is a personal experience, which is only accessible to the rest of world through interpretation. We set out to identify a neural correlate of visual awareness, using brief subliminal and supraliminal verbal stimuli while measuring cerebral blood flow distribution with H215O PET. Awareness of visual verbal stimuli differentially activated medial parietal association cortex (precuneus), which is a polymodal sensory cortex, and dorsolateral prefrontal cortex, which is thought to be primarily executive. Our results suggest participation of these (...) higher order perceptual and executive cortical structures in visual verbal awareness. (shrink)

Traditional research on emotion-face processing has primarily focused on the expression of basic emotions using adult emotional face stimuli. Stimulus sets featuring child faces or emotions other than basic emotions are rare. The current study describes the acquisition and evaluation of the Qingdao Preschooler Facial Expression set, a facial stimulus set with images featuring 54 Chinese preschoolers’ emotion expressions. The set includes 712 standardized color photographs of six basic emotions, five discrete positive emotions, and a neutral expression. The validity (...) of the pictures was examined based on 43 adult raters’ online evaluation, including agreement between designated emotions and raters’ labels, as well as intensity and representativeness scores. Overall, these data should contribute to the developmental and cross-cultural research on children’s emotion expressions and provide insights for future research on positive emotions. (shrink)

Ned Block’s Overflow Argument purports to establish that the neural basis of phenomenal consciousness is independent of the neural basis of access consciousness. In a recent paper, Block’s argument has been challenged by Peter Carruthers. Carruthers concedes the truth of one of the argument’s key steps, namely, that phenomenal consciousness overflows what is in working memory. At the same time, he rejects the conclusion of the argument by developing an account of this overflow that is alternative to Block’s. In this (...) paper, I argue that Carruthers’s account does not pose a real threat to the Overflow Argument. The overall plausibility of Carruthers’s account rests on the empirical plausibility of a claim concerning global broadcasting which, albeit intuitively plausible in light of a lightly-sketched picture of the impact of attention upon neural matters, he offers no sufficient empirical evidence for. Drawing on some important imaging studies that reveal striking facts about neural responses to visual stimuli, I argue for two intimately related claims: first, that the intuitive plausibility of claims like Carruthers’s is not a guarantee of empirical plausibility; second, that as concerns the same claims, strong empirical evidence is needed before confident judgments of empirical plausibility can reasonably be formulated. (shrink)

Eighty-four undergraduate male subjects were tachistoscopically exposed either to an experimental message designed to arouse anxiety , or to a neutral control message , at 4 ms or 200 ms durations. Electrodermal responses were recorded before, during and after exposure to the critical messages. Three measures of awareness of 4 ms stimuli were used; recall, recognition and discrimination. No evidence of stimulus awareness was found on any of these measures. Only subjects exposed to the experimental message at 4 ms (...) durations showed a significant increase in EDR from pre-exposure to message exposure period. These results support Silverman's hypothesis that drive-related stimuli must be presented subliminally in order to produce significant effects on behavior, and are consistent with Bornstein's hypothesis that stimulus awareness inhibits responding to drive- and affect-related stimuli. (shrink)

Masked stimuli can affect the preparation of a motor response to subsequently presented target stimuli. Under some conditions, reactions to the main stimulus can be facilitated or inhibited when preceded by a compatible prime . In the majority of studies in which inverse priming was demonstrated arrows pointing left or right were used as prime and targets. There is, however, evidence that arrows are special overlearned stimuli which are processed in a favorable way. Here we report three (...) experiments designated to test whether the “arrowness” of primes/targets is a sufficient condition for inverse priming. The results clearly show that although inverse priming appeared when non-arrow shapes were used, the magnitude of the priming effect was larger with arrows. The possible reasons for this effect are discussed. (shrink)

We examined effects of exposure to unreportable images of spiders on approach towards a tarantula. Pretests revealed awareness of the stimuli was at chance. Participants high or low on fear of spiders were randomly assigned to receive computer-generated exposure to unreportable pictures of spiders or outdoor scenes. They then engaged in a Behavioral Approach Task with a live tarantula. Non-fearful participants completed more BAT items than spider-fearful individuals. Additionally, as predicted, a significant interaction = 5.12, p < .03) between (...) fear of spiders and stimulus demonstrated that spider-fearful participants exposed to spiders completed more BAT items than spider-fearful participants exposed to control stimuli . The findings support the hypothesis that exposure to unreportable feared stimuli promotes approach towards the feared object. Future research and clinical implications were discussed. (shrink)

Pain perception arises from a complex interaction between a nociceptive stimulus and different emotional and cognitive factors, which appear to be mediated by both automatic and controlled systems. Previous evidence has shown that whereas conscious processing of unpleasant stimuli enhances pain perception, emotional influences on pain under unaware conditions are much less known. The aim of the present study was to investigate the modulation of pain perception by unconscious emotional pictures through an emotional masking paradigm. Two kinds of both (...) somatosensory (painful and non-painful) and emotional stimulation (negative and neutral pictures) were employed. Fifty pain-free participants were asked to rate the perception of pain they were feeling in response to laser-induced somatosensory stimuli as faster as they can. Data from pain intensity and reaction times were measured. Statistical analyses revealed a significant effect for the interaction between pain and emotional stimulation, but surprisingly this relationship was opposite to expected. In particular, lower pain intensity scores and longer reaction times were found in response to negative images being strengthened this effect for painful stimulation. Present findings suggest a clear pain perception modulation by unconscious emotional contexts. Attentional capture mechanisms triggered by unaware negative stimulation could explain this phenomenon leading to a withdrawal of processing resources from pain. (shrink)

We asked whether the influence of an invisible prime on movement is dependent on conscious movement expectations. Participants reached to a central target, which triggered a directional prime–mask arrow sequence. Participants were instructed that the visible arrows would most often signal a movement modification in a specific direction. Kinematic analyses revealed that responses to the visible mask were influenced by participants’ intentional bias, as movements were fastest when the more probable mask was displayed. In addition, responses were influenced by the (...) invisible prime without regard to its relationship to the more probable mask. Analysis of the time of initial trajectory modifications revealed that both primes influenced responses in a similar manner after accounting for participants’ bias. These results imply that invisible stimuli automatically activate their associated responses and that unconscious priming of the motor system is insensitive to the conscious expectations of the participant making the pointing movements. (shrink)