Unconscious Priming Effects Research Articles

Two masked prime arrows simultaneously affect a response to a target: Revealing of an additive unconscious priming effect.

Since there are many sources of unconscious information in our minds, there is a possibility that multiple channels of unconscious information can affect a response at the same time. However, this question has been largely ignored by researchers. In the present study, we presented two opposite pointing arrows as the masked primes followed by a target arrow. The results suggested that the two directions in which the two prime arrows are pointing influenced the response to the target simultaneously and additively, that is, the overall priming effect caused by the two opposite pointing prime arrows was equal to the net effect of the individual congruent effect elicited by the same pointing prime arrow and the individual incongruent priming effect induced by the prime arrow poitning in the opposite direction. In addition, in Experiment 1, a biased delayed response to the target was observed when the target arrow and the opposite pointing prime arrow were closely positioned in space due to Gestalt continuity and closure grouping. According to these results, the "independent unconscious influence" and "reverse unconscious selection" hypotheses are proposed.

The Semantic Integration of Multiple Unconscious Stimuli in Creative Problem‐Solving

ABSTRACTThe process of creative problem‐solving (CPS) commonly demands that individuals consciously or unconsciously integrate creative ideas from a vast array of diverse information. Using a masked priming paradigm and the Chinese remote associates test (RAT), this study provides innovative behavioral evidence for the integration of multiple unconscious stimuli during CPS. In Experiment 1, three masked Chinese characters were simultaneously presented in the RAT, the first and third characters could be combined to form an answer. Two Chinese two‐character words were presented in parallel, each containing the answer in Experiment 2, and required the complete word information to be split and subsequently re‐integrated in a more complex manner than in Experiment 1. Interestingly, in both the experiments, multiple unconsciously processed stimuli generated a priming effect on creative performance. Specifically, a positive priming effect was observed in response to the difficult RATs, whereas a negative priming effect was observed in response to the easy RATs. Overall, our study verified that semantic integration between different unconsciously perceived stimuli can occur, which provides insights into the mechanisms underlying unconscious priming effects and contributes to a better understanding of how creative cognitive processing is influenced by multiple types of unconscious information.

Multiple sources of unconscious-information processing affect a single response: independent unconscious priming effects

At present there is little knowledge on whether and how multiple pieces of unconscious information can simultaneously affect a single conscious response. In the present study, we manipulated the congruency relation between a masked prime arrow and the target arrow, as well as that between masked flankers and the target arrow. The results demonstrated that the masked prime and flankers produced independent unconscious priming effects on the response to the target. In the process of studying the above phenomenon, two secondary findings were made. First, although the prime congruency effect was obtained, the flanker congruency effect was smaller when the flankers were displayed simultaneously with the target than when they were displayed sequentially before the target. This suggested that priming stimulation required enough time to be processed to a sufficient extent to produce an unconscious priming effect. Second, when the prime stimulus was removed, leaving only the flankers, the flanker priming effect increased, suggesting that the attention attracted to the prime and its conscious mask could also reduce the flanker congruency effect. These results observed across several experiments were replicated in one within-subjects experiment. We proposed an “independent unconscious influence hypothesis” for the phenomenon. This hypothesis was further integrated into a more comprehensive unconscious information processing model. The possible causes of the observed phenomena were discussed.

The Right Inferior Frontal Gyrus Plays an Important Role in Unconscious Information Processing: Activation Likelihood Estimation Analysis Based on Functional Magnetic Resonance Imaging.

Unconsciousness is a kind of brain activity that occurs below the level of consciousness, and the masked priming paradigm is a classic paradigm to study unconscious perceptual processing. With the deepening of unconscious perception research, different researchers mostly use different experimental materials and different masked priming paradigms in a single experiment but not for the comprehensive analysis of the unconscious information processing mechanism itself. Thus, the purpose of this study is to conduct a comprehensive analysis through a cross-experimental paradigm, cross-experimental materials, and cross-experimental purposes. We used activation likelihood estimation to test functional magnetic resonance imaging studies, involving 361 subjects, 124 foci in eight studies representing direct comparison of unconscious processing with baseline, and 115 foci in 10 studies representing direct comparison of unconscious priming effects. In the comparison of unconscious processing and baseline, clusters formed in the left superior parietal gyrus, the right insular gyrus, and the right inferior frontal gyrus (IFG) triangular part after correcting for familywise error (FWE). In the comparison of priming effects, clusters formed in only the right IFG triangular part after correcting for FWE. Here, we found that ventral and dorsal pathways jointly regulate unconscious perceptual processes, but only the ventral pathway is involved in the regulation of unconscious priming effects. The IFG triangular part is involved in the regulation of unconscious perceptual processing and unconscious priming effects and may be an important brain area in unconscious information processing. These preliminary data provide conditions for further study of the neural correlation of unconscious information processing.

Faster might not be better: Pictures may not elicit a stronger unconscious priming effect than words when modulated by semantic similarity.

It has been suggested that unconscious semantic processing is stimulus-dependent, and that pictures might have privileged access to semantic content. Those findings led to the hypothesis that unconscious semantic priming effect for pictorial stimuli would be stronger as compared to verbal stimuli. This effect was tested on pictures and words by manipulating the semantic similarity between the prime and target stimuli. Participants performed a masked priming categorization task for either words or pictures with three semantic similarity conditions: strongly similar, weakly similar, and non-similar. Significant differences in reaction times were only found between strongly similar and non-similar and between weakly similar and non-similar, for both pictures and words, with faster overall responses for pictures as compared to words. Nevertheless, pictures showed no superior priming effect over words. This could suggest the hypothesis that even though semantic processing is faster for pictures, this does not imply a stronger unconscious priming effect.

Do semantic priming and retrieval of stimulus-response associations depend on conscious perception?

What function does conscious perception serve in human behavior? Many studies relied on unconscious priming to demonstrate that unseen stimuli can be extensively processed. However, showing a small unconscious priming effect falls short of showing that the process underlying such priming is independent of conscious perception. Here, we investigated to what extent the retrieval of learned stimulus-response associations and semantic priming depend on conscious perception by using a liminal-prime paradigm that allows comparing conscious and unconscious processing under the same stimulus conditions. The results revealed two striking dissociations. First, S-R priming was entirely independent of conscious perception, whereas semantic processing was strongly enhanced by it. Second, while priming emerged on fast trials for all conditions, only conscious semantic priming was observed on slow trials. The implications of these findings for the time course of response priming and for the contribution of unconscious processes to fast vs. slow responses are discussed.

Reexamining unconscious response priming: A liminal-prime paradigm.

Research on the limits of unconscious processing typically relies on the subliminal-prime paradigm. However, this paradigm is limited in the issues it can address. Here, we examined the implications of using the liminal-prime paradigm, which allows comparing unconscious and conscious priming with constant stimulation. We adapted an iconic demonstration of unconscious response priming to the liminal-prime paradigm. On the one hand, temporal attention allocated to the prime and its relevance to the task increased the magnitude of response priming. On the other hand, the longer RTs associated with the dual task inherent to the paradigm resulted in response priming being underestimated, because unconscious priming effects were shorter-lived than conscious-priming effects. Nevertheless, when the impact of long RTs was alleviated by considering the fastest trials or by imposing a response deadline, conscious response priming remained considerably larger than unconscious response priming. These findings suggest that conscious perception strongly modulates response priming.

Unconscious priming effect in visual scene with multiscale objects

Unconscious priming effect in visual scene with multiscale objects

Invisible Stimuli, Implicit Thresholds: Why Invisibility Judgments Cannot be Interpreted in Isolation.

Some studies of unconscious cognition rely on judgments of participants stating that they have “not seen” the critical stimulus (e.g., in a masked-priming experiment). Trials in which participants gave invisibility judgments are then treated as those where the critical stimulus was “subliminal” or “unconscious,” as opposed to trials with higher visibility ratings. Sometimes, only these trials are further analyzed, for instance, for unconscious priming effects. Here I argue that this practice requires implicit assumptions about subjective measures of awareness incompatible with basic models of categorization under uncertainty (e.g., modern signal-detection and threshold theories). Most importantly, it ignores the potential effects of response bias. Instead of taking invisibility judgments literally, they would better be employed in parametric experiments where stimulus visibility is manipulated systematically, not accidentally. This would allow studying qualitative and double dissociations between measures of awareness and of stimulus processing per se.

Confabulating reasons for behaving bad: The psychological consequences of unconsciously activated behaviour that violates one's standards

AbstractNumerous studies have been conducted to demonstrate that behaviours are frequently activated unconsciously. The present studies investigate the downstream psychological consequences of such unconscious behaviour activation, building on work on the explanatory vacuum and post‐priming misattribution. It was hypothesized that unconsciously activated behaviours trigger a negative affective response if the behaviour violates a personal standard and that this negative affect subsequently motivates people to confabulate a reason for the behaviour. Results provided evidence for this mediated moderation model. Study 1 showed that participants who were primed to act less prosocially indeed reported increased levels of negative affect and, as a result, were inclined to confabulate a reason for their behaviour. Study 2 replicated these findings in the domain of eating and provided evidence for the moderating role of personal standards as well as the entire mediated moderation model. These findings have relevant theoretical implications as they add to the modest number of studies that demonstrate that the effect of unconscious priming may extend well beyond performing the primed behaviour itself to influence subsequent affect and attribution processes. Copyright © 2014 John Wiley & Sons, Ltd.

The relationship between the objective identification threshold and priming effects does not provide a definitive boundary between conscious and unconscious perceptual processes

The Objective Threshold/Strategic Model (OT/S) proposes that strong, qualitative inferences of unconscious perception can be made if the relationship between perceptual sensitivity (typically priming effects) and stimulus visibility is nonlinear and nonmonotonic. The model proposes a nadir in priming effects at the objective identification threshold (identification d'=0). These predictions were tested with masked semantic priming and repetition priming of a lexical decision task. The visibility of the prime stimuli was systematically varied above and below the objective identification threshold. The obtained relationship between prime visibility and priming facilitation was nonlinear, but the results failed to confirm a nadir in priming effects at the objective identification threshold. We conclude that the objective identification threshold does not necessarily indicate the point where presumably unconscious priming effects might be inhibited by conscious cognitive processes.

Control of oculomotor reflexes: independent effects of strategic and automatic preparation

The reduction in saccade latency when the fixation point is removed (fixation offset effect-FOE) reflects the degree to which fixation neurons are under influence by a stimulus at fixation. Strategic manipulations of oculomotor readiness that bring these neurons under endogenous control reduce the magnitude of the FOE. Using an aging foreperiod paradigm, and the FOE as a marker for cortical control of reflexive fixation, we showed that, for both prosaccades and antisaccades, increasing preparation across the foreperiod reduced both saccade latency and the FOE. Consistent with Los's trace conditioning account, these effects reflected greater preparation for trials when the current short foreperiod was preceded by a trial with a short foreperiod. The FOE was also smaller for antisaccades than for prosaccades demonstrating strategic modulation. However, the effects of trace conditioning were comparable in the two tasks, demonstrating that strategic and unconscious priming effects both independently modulate the control of ocular fixation.

Unconscious Activation of the Cognitive Control System in the Human Prefrontal Cortex

Using functional magnetic resonance imaging, we tested whether unconscious information can influence the cognitive control system in the human prefrontal cortex. Volunteers had to prepare to perform either a phonological judgment or a semantic judgment on an upcoming word, based on the instruction given at the beginning of each trial. However, in some trials they were visually primed to prepare for the alternative (i.e., "wrong") task, and this impaired their performance. This priming effect is taken to depend on unconscious processes because the effect was present even when the volunteers could only discriminate the identity of the primes at chance level. Furthermore, the effect was stronger when the visibility of the prime was near zero than when the visibility of the prime was significantly higher. When volunteers were unconsciously primed to perform the alternative task, there was also decreased neural activity in the brain areas relevant to the instructed task and increased neural activity in the brain areas relevant to the alternative task, which shows that the volunteers were actually engaged in the wrong task, instead of simply being distracted. Activity in the mid-dorsolateral prefrontal cortex was also found to be associated with this unconscious priming effect. These results suggest that the cognitive control system in the prefrontal cortex is not exclusively driven by conscious information, as has been believed previously.

Exogenous spatial cueing modulates subliminal masked priming

An experiment combined exogenous spatial cueing with masked repetition priming. The task consisted of an alphabetic decision task (letter/pseudo-letter classification) with central targets and peripheral primes that were preceded by a valid or invalid spatial cue in the form of an exogenous abrupt onset. In an analysis including only participants who were not aware of prime stimuli, exogenous location cueing was found to reliably modulate the size of unconscious priming effects. These findings suggest that in early vision the exogenous cue boosts the signal at the location of the cue resulting in a higher gain for the subliminal prime. Our findings therefore suggest that exogenous cueing can affect the first feedforward sweep of information through the brain, a processing stream which is considered to be automatic and unconscious.

Unconscious and conscious priming by forms and their parts

Using metacontrast masking techniques, in two experiments we compare unconscious and conscious response priming by targets consisting of either whole forms or else their parts. In Experiment 1 we investigate the contribution of whole forms and their figural primitives, viz., edges and corners, to the unconscious priming effect. As expected, choice RTs were fast when the invisible target and visible mask shape pairings were congruent and slower when they were incongruent. This trend, while strongest for whole-targets, also held for the target primes composed only of corners but did not hold for target primes composed only of sides. Experiment 2 showed, replicating the results of Experiment 1, that while invisible corner targets produced weaker priming effects than invisible whole targets, paradoxically visible corner target produced stronger priming effects than visible whole targets. Taken together the results of the two experiments indicate (a) that unconscious target representations and, thus, unconscious priming effects are strongest when the target is a complete rather than a partial configuration, (b) that conjunctions of line or edge orientations forming corners produce stronger unconscious target representations and priming effects than do unconscious target representations formed from nonconjoined edge or line primitives, (c) that metacontrast masking of form occurs at or beyond levels of visual processing at which feature integration of visual form primitives occurs, and (d) that, when consciously perceived, partial forms can act as stronger primes than whole forms.

On the masking and disclosure of unconscious elaborate processing. A reply to Van Opstal, Reynvoet, and Verguts (2005)

We have recently argued that unconscious numerical stimuli might activate responses by a match with prespecified action trigger codes (action trigger account) rather than by semantic prime processing (elaborate processing account). [Van Opstal, F., Reynvoet, B., and Verguts, T. (2005). How to trigger elaborate processing? A comment on Kunde, Kiesel, and Hoffmann (2003). Cognition] replicate one piece of evidence for our inference—an inefficiency of primes not presented in target format (verbal or Arabic). But this was found only with letter masks and not with hash masks. The authors conclude that letter masks block unconscious prime processing, and that elaborate processing can account for unconscious priming effects if all its (sometimes subtle) side conditions are considered. We agree that the type of mask in general is an important factor in priming studies but we note that (i) the authors' mask-blocking hypothesis is not well supported by the data, (ii) clear evidence for semantic prime processing in their study is lacking and, (iii) differences in mask efficiency (rather than mask type) might account for the conflicting results. To corroborate this inference we replicate van Opstal et al.'s results with letter masks but reduced mask efficiency. Altogether their data do not challenge the action-trigger account nor do they strongly support the elaborate processing view.

The effect of unconscious priming on temporal production

We examined the effects of unconscious priming on temporal-interval production. In Experiment 1, participants were instructed to keep visual displays on a screen for 2500 ms intervals. Half of the displays were repeated across blocks throughout the entire experiment, and the others were newly generated from trial to trial. The displays consisted of patterns so complex that the participants could not intentionally memorize them. The results showed that significantly more time elapsed for old displays than for new displays before participants indicated that a 2500 ms interval had elapsed. Experiment 2 replicated this effect and excluded an alternative account based on perceived pattern complexity. The effect of repetitive presentation was obtained despite the fact the participants did not recognize the repetition, suggesting that unconscious priming increased temporal production. These results suggest that time perception is affected by an unconscious process.

Dissociation of conscious and unconscious repetition priming effect on event-related potentials

Although the neural basis of the unconscious priming effect has previously been investigated, the results of these studies have possibly been contaminated by a conscious priming effect. The aim of the present study was to dissociate the effects of conscious and unconscious priming on event-related potential (ERP) by using the process-dissociation procedure. A prime word was presented briefly, followed by a word-stem, in each trial. Under the inclusion condition, subjects were instructed to complete the word-stem using the prime word, while under the exclusion condition subjects were asked to complete the word-stem with a word not seen as prime. The behavioral priming effect was obtained under both conditions, indicating that the prime words were processed unconsciously and influenced the word-stem completion task. We found that two ERP components were affected by repetition priming. First, the N400 amplitude was decreased by word repetition under the inclusion condition, but not under the exclusion condition. This result suggests that N400 would reflect conscious lexical processing, but not unconscious lexical activation. Second, the negativity at left front lateral region was enhanced by word repetition under the exclusion condition. We discuss this finding herein in relation to the activity of the left inferior prefrontal cortex with regard to word semantic processing.

Unconscious color priming occurs at stimulus- not percept-dependent levels of processing.

Although past studies have shown that visual information can be processed without awareness, the types and levels of this processing have yet to be determined. We used metacontrast masking to explore unconscious priming effects of white, blue, and green stimuli generated on a color video display. We found that a white prime tends to act more like a green than a blue one. Color confusions among unmasked and masked primes and calibrations of the display phosphors show that physical rather than perceptual properties of the stimuli best explain the white prime's effects. We conclude that unconscious color priming in normal observers occurs at early wavelength-dependent levels of processing prior to later color-percept-dependent levels.

Long-term semantic memory versus contextual memory in unconscious number processing.

Subjects classified visible 2-digit numbers as larger or smaller than 55. Target numbers were preceded by masked 2-digit primes that were either congruent (same relation to 55) or incongruent. Experiments 1 and 2 showed prime congruency effects for stimuli never included in the set of classified visible targets, indicating subliminal priming based on long-term semantic memory. Experiments 2 and 3 went further to demonstrate paradoxical unconscious priming effects resulting from task context. For example, after repeated practice classifying 73 as larger than 55, the novel masked prime 37 paradoxically facilitated the "larger" response. In these experiments task context could induce subjects to unconsciously process only the leftmost masked prime digit, only the rightmost digit, or both independently. Across 3 experiments, subliminal priming was governed by both task context and long-term semantic memory.