The nature of unconscious information processing is a heavily debated issue in cognitive science, and neuroscience. Traditionally, it has been thought that unconscious cognitive processing is restricted to knowledge that is strongly prepared by conscious processes. In three experiments, we show that the task that is performed consciously can also be applied unconsciously to items outside the current task set. We found that a same–different judgment of two target stimuli was also performed on two subliminally presented prime stimuli. This was (...) true for target and prime stimuli from entirely different categories, as well as for prime and target stimuli at different levels of abstraction. These results reveal that unconscious processing can generalize more widely than previously accepted. (shrink)

We propose a new masking technique for masking word stimuli. Drawing on the phenomena of metacontrast and paracontrast, we alternately presented two prime displays of the same word with the background color in one display matching the font color in the other display and vice versa. The sequence of twenty alterations was sandwich-masked by structure masks. Using this masking technique, we conducted evaluative priming experiments with positive and negative target and prime words. Significant priming effects were found – for primes (...) and targets drawn from the same as well as from different word sets. Priming effects were independent of prime discrimination performance in direct tests and they were still significant after the sample was restricted to those participants who showed random responding in the direct test. (shrink)

We used a qualitative dissociation procedure to assess semantic priming from spatially attended and unattended masked words. Participants categorized target words that were preceded by parafoveal prime words belonging to either the same or the opposite category as the target. Using this paradigm, only non-strategic use of the prime would result in facilitation of the target responses in related trials. Primes were immediately masked or masked with a delay, while spatial attention was allocated to the primes’ location or away from (...) the primes’ location. Immediate masked, strongly related primes facilitated target responses irrespective of the spatial attention. Delayed masked, related primes led to reversed or facilitatory priming depending on whether they were cued or uncued. These findings demonstrate that perceiving a stimulus with or without awareness depends on both stimulus quality and attention orienting and that non-strategic priming can be observed from clear visible but spatially unattended words. (shrink)

The commentators have raised many pertinent points that allow us to refine and clarify our view. We classify our response comments into seven sections: automaticity; developmental and educational questions; priming; multiple representations or multiple access(?); terminology; methodological advances; and simulated cognition and numerical cognition. We conclude that the default numerical representations are not abstract.

Cohen Kadosh & Walsh (CK&W) present convincing evidence indicating the existence of notation-specific numerical representations in parietal cortex. We suggest that the same conclusions can be drawn for a particular type of numerical representation: the representation of time. Notation-dependent representations need not be limited to number but may also be extended to other magnitude-related contents processed in parietal cortex (Walsh 2003).

Visual stimuli that are made invisible by a following mask can nonetheless affect motor responses. To localize the origin of these target priming effects we used the psychological refractory period paradigm. Participants classified tones as high or low, and responded to the position of a visual target that was preceded by a prime. The stimulus onset asynchrony between both tasks varied. In Experiment 1 the tone task was followed by the position task and SOA dependent target priming effects were observed. (...) When the visual position task preceded the tone task in Experiment 2, with short SOA the priming effect propagated entirely to the tone task yielding faster responses to tones on visually congruent trials and delayed responses to tones on visually incongruent trials. Together, results suggest that target priming effects arise from processing before and at the level of the central bottleneck such as sensory analysis and response selection. (shrink)

Using an explicit task cuing paradigm, we tested whether masked cues can trigger task-set activation, which would suggest that unconsciously presented stimuli can impact cognitive control processes. Based on a critical assessment of previous findings on the priming of task-set activation, we present two experiments with a new method to approach this subject. Instead of using a prime, we varied the visibility of the cue. These cues either directly signaled particular tasks in Experiment 1, or certain task transitions in Experiment (...) 2. While both masked task and transition cues affected task choice, only task cues affected the speed of task performance. This observation suggests that task-specific stimulus–response rules can be activated only by masked cues that are uniquely associated with a particular task. Taken together, these results demonstrate that unconsciously presented stimuli have the power to activate corresponding task sets. (shrink)

Visual masking of primes lowers prime visibility but spares processing of primes as reflected in prime–target congruence and prime–response compatibility effects. However, the question is how to appropriately measure prime visibility. Here, we tested the influence of three procedural variables on prime visibility measures: prime–target similarity, prime–response similarity, and the variability of prime–response mappings. Our results show that a low prime–target similarity is a favorable condition for a prime visibility measure because it increases the sensitivity of this measure in comparison (...) to a high prime–target similarity. (shrink)

The nature of unconscious information processing is a heavily debated issue in cognitive science , and neuroscience . Traditionally, it has been thought that unconscious cognitive processing is restricted to knowledge that is strongly prepared by conscious processes . In three experiments, we show that the task that is performed consciously can also be applied unconsciously to items outside the current task set. We found that a same–different judgment of two target stimuli was also performed on two subliminally presented prime (...) stimuli. This was true for target and prime stimuli from entirely different categories, as well as for prime and target stimuli at different levels of abstraction. These results reveal that unconscious processing can generalize more widely than previously accepted. (shrink)

Masked priming experiments occasionally revealed surprising effects: Participants responded slower for congruent compared to incongruent primes. This negative congruency effect was ascribed to inhibition of prime-induced activation [Eimer, M., & Schlaghecken, F. . Response faciliation and inhibition in subliminal priming. Biological Psychology, 64, 7–26.] that sets in if the prime activation is sufficiently strong. The current study tests this assumption by implementing manipulations designed to vary the amount of prime-induced activation in three experiments. In Experiments 1 and 3, NCEs were (...) observed despite reduced prime-induced activation. Experiment 2 revealed no NCE with at least similar prime strength. Thus, the amount of prime activation did not predict whether or not NCEs occurred. The findings are discussed with regard to the inhibition account and the recently proposed account of mask-induced activation [cf. Lleras, A., & Enns, J. T. . Negative compatibility or object updating? A cautionary tale of mask-dependent priming. Journal of Experimental Psychology: General, 133, 475–493; Verleger, R., Jaskowski, P., Aydemir, A., van der Lubbe, R. H. J., & Groen, M. . Qualitative differences between conscious and nonconscious processing? On inverse priming induced by masked arrows. Journal of Experimental Psychology: General, 133, 494–515]. (shrink)

We show how an epistemology informed by cognitive science promises to shed light on an ancient problem in the philosophy of mathematics: the problem of exactness. The problem of exactness arises because geometrical knowledge is thought to concern perfect geometrical forms, whereas the embodiment of such forms in the natural world may be imperfect. There thus arises an apparent mismatch between mathematical concepts and physical reality. We propose that the problem can be solved by emphasizing the ways in which the (...) brain can transform and organize its perceptual intake. It is not necessary for a geometrical form to be perfectly instantiated in order for perception of such a form to be the basis of a geometrical concept. (shrink)

How does the brain generate our experience of being in control over our actions and their effects? Here, we argue that the perception of events as self-caused emerges from a comparison between anticipated and actual action-effects: if the representation of an event that follows an action is activated before the action, the event is experienced as caused by one’s own action, whereas in the case of a mismatch it will be attributed to an external cause rather than to the self. (...) In a subliminal priming paradigm we show that participants overestimated how much control they had over objectively uncontrollable stimuli, which appeared after free- or forced-choice actions, when a masked prime activated a representation of the stimuli immediately before each action. This prime-induced control-illusion was independent from whether primes were consciously perceived. Results indicate that the conscious experience of control is modulated by unconscious anticipations of action-effects. (shrink)

Previous research has shown that subliminally presented stimuli accelerate or delay responses afforded by supraliminally presented stimuli. Our experiments extend these findings by showing that unconscious stimuli even affect free choices between responses. Thus, actions that are phenomenally experienced as freely chosen are influenced without the actor becoming aware of the manipulation. However, the unconscious influence is limited to a response bias, as participants chose the primed response only in up to 60% of the trials. LRP data in free choice (...) trials indicate that the prime was not ineffective in trials in which participants chose the non-primed response as then it delayed performance of the incongruently primed response. (shrink)

The aim of this study was to investigate unconscious priming by the use of a spatial mirror-masking paradigm. Words and nonwords with no under-length letters are mirrored at their horizontal axis. The results are figures of geometric-like forms that contain letters in their upper part. In the three experiments reported in this study, a priming procedure used such mirrored words and nonwords as primes. Participants were ignorant of the nature of the construction of the stimuli. Perceptual reports of the participants (...) revealed that they did not realize that words were hidden in the primes. Nevertheless, they showed priming in all three experiments. Priming effects were replicated with prime–target SOAs of between 1 and 3 s. Functional dissociations were found between ignorant and informed participants. Informed groups showed perceptual and semantic priming, while ignorant groups showed only perceptual priming. (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)

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)

In masked priming tasks responses are usually faster when prime and target require identical rather than different responses. Previous research has extensively manipulated the nature and number of response-affording stimuli. However, little is known about the constraints of masked priming regarding the nature and number of response alternatives. The present study explored the limits of masked priming in a six-choice reaction time task, where responses from different fingers of both hands were required. We studied participants that were either experts for (...) the type of response or novices. Masked primes facilitated responding to targets that required the same response, responses with a different finger of the same hand, and with a homologous finger of the other hand. These effects were modulated by expertise. The results show that masked primes facilitate responding especially for experts in the S–R mapping and with increasing similarity of primed and required response. (shrink)

Amidst the many brain events evoked by a visual stimulus, which are specifically associated with conscious perception, and which merely reflect non-conscious processing? Several recent neuroimaging studies have contrasted conscious and non-conscious visual processing, but their results appear inconsistent. Some support a correlation of conscious perception with early occipital events, others with late parieto-frontal activity. Here we attempt to make sense of those dissenting results. On the basis of a minimal neuro-computational model, the global neuronal workspace hypothesis, we propose a (...) taxonomy which distinguishes between vigilance and access to conscious report, as well as between subliminal, preconscious and conscious processing. We suggest that these distinctions map onto different neural mechanisms, and that conscious perception is systematically associated with a sudden surge of parieto-frontal activity causing top-down amplification. (shrink)

Comparisons of indirect measures with direct measures can help elucidate the relationship between nonconscious and conscious perception. We report three experiments on masked word priming in which we observed a negative correlation between prime discriminability and priming , i.e. where priming decreased with increasing prime visibility. While such observations are rare , they may indicate a conflict between conscious and nonconscious processing when primes are shown close to the subjective visibility threshold for the priming-relevant information. For instance, such a conflict (...) could occur between nonconscious processing of a prime’s meaning and conscious perception of prime letters. Theoretical accounts that discuss similar conflicts assume that the conflict is resolved either by automatically prioritising conscious processes or by discounting the estimated confusion caused by a prime-target pair . In both cases, priming is predicted to decrease when prime visibility increases from below threshold to perithreshold levels. Therefore, we suggest that negative priming-d’ relationships are most likely observed when the d’ measure assesses prime visibility at a level of representation that is below the level of representation at which priming arises, in terms of a putative hierarchy of word processing. (shrink)

How internal categories influence how we perceive the world is a fundamental question in cognitive sciences. Yet, the relation between perceptual awareness and perceptual categorization has remained largely uncovered so far. Here, we addressed this question by focusing on face perception during subliminal and conscious perception. We used morphed continua between two face identities and we assessed, through a masked priming paradigm, the perceptual processing of these morphed faces under subliminal and supraliminal conditions. We found that priming from subliminal faces (...) followed linearly the information present in the primes, while priming from visible faces revealed a non-linear profile, indicating a categorical processing of face identities. Our results thus point to a special relation between perceptual awareness and categorical processing of faces, and support the dissociation between two modes of information processing: a subliminal mode involving analog treatment of stimuli information, and a supraliminal mode relying on discrete representation. (shrink)

A series of five experiments investigated the extent of subliminal processing of negation. Participants were presented with a subliminal instruction to either pick or not pick an accompanying noun, followed by a choice of two nouns. By employing subjective measures to determine individual thresholds of subliminal priming, the results of these studies indicated that participants were able to identify the correct noun of the pair – even when the correct noun was specified by negation. Furthermore, using a grey-scale contrast method (...) of masking, Experiment 5 confirmed that these priming effects were evidenced in the absence of partial awareness, and without the effect being attributed to the retrieval of stimulus–response links established during conscious rehearsal. (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)

A theory is proposed that views emotional feelings as pivotal for action control. Feelings of emotions are valued interoceptive signals from the body that become multimodally integrated with perceptual contents from registered and mentally simulated events. During the simulation of a perceptual change from one event to the next, a conative feeling signal is created that codes for the wanting of a specific perceptual change. A wanted perceptual change is weighted more strongly than alternatives, increasing its activation level on the (...) cognitive level and that of associated motor structures that produced this perceptual change in the past. As a consequence, a tendency for action is generated that is directed at the production of the wanted perception. (shrink)

Executive control of attention refers to processes that detect and resolve conflict among competing thoughts and actions. Despite the high-level nature of this faculty, the role of awareness in executive control of attention is not well understood. In this study, we used interocular suppression to mask the flankers in an arrow flanker task, in which the flankers and the target arrow were presented simultaneously in order to elicit executive control of attention. Participants were unable to detect the flanker arrows or (...) to reliably identify their direction when masked. There was a typical conflict effect (prolonged reaction time and increased error rate under flanker-target incongruent condition compared to congruent condition) when the flanker arrows were unmasked, while the conflict effect was absent when the flanker arrows were masked with interocular suppression. These results suggest that blocking awareness of competing stimuli with interocular suppression prevents the involvement of executive control of attention. (shrink)

Recent research suggests that processing of irrelevant information can be modulated in a rapid online fashion by contextual information in the task environment depending on the usefulness of that information in different contexts. Congruency effects evoked by irrelevant stimulus attributes are smaller in contexts with high proportions of incongruent trials and larger in contexts with high proportions of congruent trials . The present study investigates these context-adaptation effects in a masked-priming paradigm. Context-specific adaptation effects transfer to stimulus identities that are (...) equiprobale in all contexts – an observation that renders explanations in terms of event-learning processes unlikely. Yet, context-specific effects vanished when the irrelevant information remained unconscious. The results suggest that context-specific adaptation of congruency effects reflect cognitive control operations that alter the processing of irrelevant information depending on the experienced utility of that information for action control. (shrink)