Links between conscious awareness and response inhibition: evidence from masked priming

Recent results from “subliminal priming” experiments have shown that masked prime stimuli which can not be consciously perceived can trigger response activation processes, but that these response activations can later be subject to inhibition. Links between conscious awareness and response inhibition were investigated by manipulating the visibility of masked prime stimuli, from clearly visible primes to prime stimuli that were inaccessible to conscious perception. Response inhibition was observed with unperceived prime stimuli, but not for suprathreshold primes. Correlations between individual prime identification thresholds and the onset of response inhibition indicate that the absence or presence of conscious awareness can predict whether or not response inhibition is elicited. These results demonstrate qualitative differences in the effects of conscious and unconscious information. It is argued that response facilitation produced by consciously available perceptual information can counteract automatic effects of self-inhibitory motor control circuits.     

Are there unconscious perceptual processes?

Blindsight and vision for action seem to be exemplars of unconscious visual processes. However, researchers have recently argued that blindsight is not really a kind of unconscious vision but is rather severely degraded conscious vision. Morten Overgaard and colleagues have recently developed new methods for measuring the visibility of visual stimuli. Studies using these methods show that reported clarity of visual stimuli correlates with accuracy in both normal individuals and blindsight patients. Vision for action has also come under scrutiny. Recent findings seem to show that information processed by the dorsal stream for online action contributes to visual awareness. Some interpret these results as showing that some dorsal stream processes are conscious visual processes (e.g., Gallese, 2007; Jacob & Jeannerod, 2003). The aim of this paper is to provide new support for the more traditional view that blindsight and vision for action are genuinely unconscious perceptual processes. I argue that individuals with blindsight do not have access to the kind of purely qualitative color and size information which normal individuals do. So, even though people with blindsight have a kind of cognitive consciousness, visual information processing in blindsight patients is not associated with a distinctly visual phenomenology. I argue further that while dorsal stream processing seems to contribute to visual awareness, only information processed by the early dorsal stream (V1, V2, and V3) is broadcast to working memory. Information processed by later parts of the dorsal stream (the parietal lobe) never reaches working memory and hence does not correlate with phenomenal awareness. I conclude that both blindsight and vision for action are genuinely unconscious visual processes.     

Unconscious task application

The nature of unconscious information processing is a heavily debated issue in cognitive science (e.g., Kouider & Dehaene, 2007), and neuroscience (e.g., Crick & Koch, 1998). Traditionally, it has been thought that unconscious cognitive processing is restricted to knowledge that is strongly prepared by conscious processes (e.g., Dehaene et al., 1998). 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.     

A hemispheric asymmetry for the unconscious perception of emotion

Previous research has demonstrated that hemispheric asymmetries for conscious visual perception do not lead to asymmetries for unconscious visual perception. These studies utilized emotionally neutral items as stimuli. The current research utilized both emotionally negative and neutral stimuli to assess hemispheric differences for conscious and unconscious visual perception. Conscious perception was measured using a subjective measure of awareness reported by participants on each trial. Unconscious perception was measured by an "exclusion task," a form of word-stem-completion task. Consistent with predictions, negative stimuli were consciously perceived most often when presented to the right hemisphere. Negative stimuli presented to the right hemisphere showed no evidence of unconscious perception, suggesting that the hemispheric asymmetry for the conscious perception of negative information occurs at the expense of unconscious perception.     

Attentional sensitization of unconscious visual processing: Top-down influences on masked priming

Classical theories of automaticity assume that automatic processes elicited by unconscious stimuli are autonomous and independent of higher-level cognitive influences. In contrast to these classical conceptions, we argue that automatic processing depends on attentional amplification of task-congruent processing pathways and propose an attentional sensitization model of unconscious visual processing: According to this model, unconscious visual processing is automatic in the sense that it is initiated without deliberate intention. However, unconscious visual processing is susceptible to attentional top-down control and is only elicited if the cognitive system is configured accordingly. In this article, we describe our attentional sensitization model and review recent evidence demonstrating attentional influences on subliminal priming, a prototypical example of an automatic process. We show that subliminal priming (a) depends on attentional resources, (b) is susceptible to stimulus expectations, (c) is influenced by action intentions, and (d) is modulated by task sets. These data suggest that attention enhances or attenuates unconscious visual processes in congruency with attentional task representations similar to conscious perception. We argue that seemingly paradoxical, hitherto unexplained findings regarding the automaticity of the underlying processes in many cognitive domains can be easily accommodated by our attentional sensitization model. We conclude this review with a discussion of future research questions regar-ding the nature of attentional control of unconscious visual processing.     

The Neural Basis of Motor-Skill Learning

Recent work indicates that motor-skill learning is supported by four processes: a strategic process that selects new goals of what to change in the environment, a perceptual-motor integration process that adjusts to new relationships between environmental stimuli and the appropriate motor response, a sequencing process that learns sequences of motor acts, and a dynamic process that learns new patterns of muscle activations. These four processes can operate in one of two modes: an unconscious mode, in which one is aware only of the goal of the movement, or a conscious mode, in which one consciously controls detailed aspects of the movement. This article provides an overview of these four processes and two modes, and describes their neural bases.     

Odogenic change of blood coagulation in humans.

The blood coagulation time as an integral sign of human homeostasis is revealed to be influenced by conscious or unconscious olfactory stimuli through autonomic mechanisms. The hemostasis of subjects with predominance of sympathetic activity is more sensitive to the olfactory stimuli than that of subjects with vagal prevalence. The effects of the olfactory stimuli upon hemostasis in humans support the viewpoint that simultaneous information and physico-chemical processes act together in parallel to play and important role in life activities of human organism (Simonov, 1981; Sudakov, 1995). Emotions, therefore, are essential in the transfer of information from the environment (Anokhin, 1966; Miltner et al., 1994). It is not excluded that even very weak stimuli which are subthreshold for conscious perception might be informational for the organism as those engaging emotional response.     

Odogenic change of blood coagulation in humans

The blood coagulation time as an integral sign of human homeostasis is revealed to be influenced by conscious or unconscious olfactory stimuli through autonomic mechanisms. The hemostasis of subjects with predominance of sympathetic activity is more sensitive to the olfactory stimuli than that of subjects with vagal prevalence. The effects of the olfactory stimuli upon hemostasis in humans support the viewpoint that simultaneous information and physico-chemical processes act together in parallel to play and important role in life activities of human organism (Simonov, 1981; Sudakov, 1995). Emotions, therefore, are essential in the transfer of information from the environment (Anokhin, 1966; Miltner et al., 1994). It is not excluded that even very weak stimuli which are subthreshold for conscious perception might be informational for the organism as those engaging emotional response.     

Unconscious Emotion

Abstract— Conscious feelings have traditionally been viewed as a central and necessary ingredient of emotion. Here we argue that emotion also can be genuinely unconscious. We describe evidence that positive and negative reactions can be elicited subliminally and remain inaccessible to introspection. Despite the absence of subjective feelings in such cases, subliminally induced affective reactions still influence people's preference judgments and even the amount of beverage they consume. This evidence is consistent with evolutionary considerations suggesting that systems underlying basic affective reactions originated prior to systems for conscious awareness. The idea of unconscious emotion is also supported by evidence from affective neuroscience indicating that subcortical brain systems underlie basic "liking" reactions. More research is needed to clarify the relations and differences between conscious and unconscious emotion, and their underlying mechanisms. However, even under the current state of knowledge, it appears that processes underlying conscious feelings can become decoupled from processes underlying emotional reactions, resulting in genuinely unconscious emotion.     

The best of both worlds: Integrating conscious and unconscious thought best solves complex decisions

Two studies address the debate over whether conscious or unconscious mental processes best handle complex decisions. According to Unconscious Thought Theory (Dijksterhuis & Nordgren, 2006) both modes of thinking have particular advantages: conscious thought can follow strict rules, whereas unconscious thought is better suited for integrating numerous decision attributes. Because most complex decisions require both adherence to precise rules and the aggregation of information, we hypothesized that complex decisions can best be made by engaging in periods of both conscious and unconscious thought. In both studies we found that the sequential integration of conscious and unconscious thought solved complex choices better than conscious or unconscious thought alone. In Study 2 we examined whether the sequential order of the integration condition matters. In line with our prediction, we found that integration worked best when unconscious thought followed conscious thought.     

Unconscious Representations 1: Belying the Traditional Model of Human Cognition

The traditional model of human cognition (TMHC) postulates an ontological and/or structural gap between conscious and unconscious mental representations. By and large, it sees higher-level mental processes as commonly conceptual or symbolic in nature and therefore conscious, whereas unconscious, lower-level representations are conceived as non-conceptual or sub-symbolic. However, experimental evidence belies this model, suggesting that higher-level mental processes can be, and often are, carried out in a wholly unconscious way and/or without conceptual representations, and that these can be processed unconsciously. This entails that the TMHC, as well as the theories on mental representation it motivates and that in turn support it, is wrong.     

Disambiguating conscious and unconscious influences: do exclusion paradigms demonstrate unconscious perception?

Does exclusion failure--responding with previously presented words despite instructions to avoid doing so--demonstrate unconscious influences? This article examines exclusion-based evidence for unconscious perception. I propose an alternative signal detection theory (SDT) framework that can account for exclusion failure and ostensibly convergent qualitative differences without positing additional unconscious perceptual mechanisms. In the proposed SDT model, exclusion failure is a criterion artifact, similar to classic SDT-based critiques of subjective threshold approaches. However, it is suggested that exclusion approaches do demonstrate that response strategies are applied only to above-criterion stimuli and thereby illustrate important qualitative differences between two conscious processes: phenomenal awareness itself and higher-order (i.e., metacognitive) decision processes.     

Four empirical tests of Unconscious Thought Theory

According to Unconscious Thought Theory, people make better decisions after unconscious than after conscious thought (Dijksterhuis, Bos, Nordgren, & van Baaren, 2006a). Unconscious Thought Theory yields four specific predictions. First, an exact replication of Dijksterhuis et al. (2006a) study should indicate that unconscious decisions are superior to conscious decisions. Second, decisions should improve with duration of conscious thought. Third, unconscious decisions should be superior to conscious decisions, even if unconscious decisions are deliberated while having access to information. Fourth, unconscious decisions should be based on a weighting strategy. We report results of four studies, featuring 480 participants, that yield no evidence in favor of these predictions. Therefore our findings cast doubt on Unconscious Thought Theory and its advice to base decisions on unconscious thought. The results of our studies suggest that it is better to base decisions on conscious thought while having access to information.     

How to trigger elaborate processing? A comment on Kunde, Kiesel, and Hoffmann (2003)

Recently, [Kunde, W., Kiesel, A., & Hoffmann, J. (2003). Conscious control over the content of unconscious cognition. Cognition, 88, 223-242] used a masked priming paradigm to argue that neither the 'elaborate processing' or the 'evolving automaticity' view can account for the processing of unconscious numerical stimuli. In our Experiment 1 we replicated [Kunde, W., Kiesel, A., & Hoffmann, J. (2003). Conscious control over the content of unconscious cognition. Cognition, 88, 223-242] Experiment 4 and show that with a less demanding mask than that used by Kunde et al., 'elaborate processing' can explain priming results given that there are side conditions to trigger elaborate processing of unconscious stimuli. The second experiment further explores this influence of the masks by increasing the relevance of the symbols by which the mask is composed. The results show that an increase in relevance of the mask is accompanied by a decrease in the priming effect, though there was no significant change in conscious awareness of the prime.     

Aging: a switch from automatic to controlled processing of sounds?

In this article, the authors show that aging differentially affects peoples' ability to automatically and voluntarily process auditory information. Young, middle-aged, and older adults matched behaviorally in an auditory discrimination task showed similar patterns of neural activity indexing the voluntary and conscious detection of deviant (i.e., target) stimuli. In contrast, a negative wave indexing automatic processing (the mismatch negativity) was elicited only in young adults for near-threshold stimuli. These results indicate that aging affects the ability to automatically register small changes in a stream of homogeneous stimuli. However, this age-related decline in automatic detection of small change in the auditor environment can be compensated for by top-down controlled processes.     

无意识思维:理论、质疑与回应

Dijksterhuis等人发现在解决复杂问题时,无意识思维的加工结果优于有意识思维,并据此提出了无意识思维理论。本文介绍了支持无意识思维理论的基本实验证据,质疑无意识思维的相关研究及对质疑的回应研究。未来研究应重点关注改进无意识思维研究范式和寻找更多影响无意识思维效应的中介变量,无意识思维加工结果如何上升到有意识层面,无意识思维的加工方式以及其在真实和高风险任务情境中的应用。     

Epinephrine,Arousal, and Emotion: A New Look at Two-factor Theory

Ever since William James, psychologists of emotion have tended to view affective states as intrinsically conscious. We argue that nonconscious affect also exists, and focus specifically on the possibility of unconscious "liking". We present evidence that positive and negative affective reactions can be elicited subliminally, while a person is completely unaware of any affective reaction at all (in addition to being unaware of the causal stimulus). Despite the absence of any detectable subjective experience of emotion, subliminally induced unconscious "liking" can influence later consumption behaviour. We suggest that unconscious "liking" is mediated by specific subcortical brain systems, such as the nucleus accumbens and its connections. Ordinarily, conscious liking (feelings of pleasure) results from the interaction of separate brain systems of conscious awareness with those core processes of unconscious affect. But under some conditions, activity in brain systems mediating unconscious core "liking" may become decoupled from conscious awareness. The result is a genuinely unconscious emotion.     

Conscious and unconscious processes: the effects of motivation

The process-dissociation procedure has been used in a variety of experimental contexts to assess the contributions of conscious and unconscious processes to task performance. To evaluate whether motivation affects estimates of conscious and unconscious processes, participants were given incentives to follow inclusion and exclusion instructions in a perception task and a memory task. Relative to a control condition in which no performance incentives were given, the results for the perception task indicated that incentives increased the participants' ability to exclude previously presented information, which in turn both increased the estimate of conscious processes and decreased the estimate of unconscious processes. However, the results also indicated that incentives did not influence estimates of conscious or unconscious processes in the memory task. The findings suggest that the process-dissociation procedure is relatively immune to influences of motivation when used with a memory task, but that caution should be exercised when the process-dissociation is used with a perception task.     

An examination of the right-hemisphere hypothesis of the lateralization of emotion

The Right-Hemisphere Hypothesis posits that emotional stimuli are perceived more efficiently by the right hemisphere than by the left hemisphere. The current research examines this hypothesis by examining hemispheric asymmetries for the conscious and unconscious perception of emotional stimuli. Negative, positive, and neutral words were presented for 17 ms to one visual field or the other. Conscious perception was measured by using a subjective report-of-awareness measure reported by participants on each trial. Unconscious perception was measured using an "exclusion task," a form of word-stem-completion task. Consistent with previous research, there was a right-hemisphere advantage for the conscious perception of negative information. As in previous studies, this advantage for conscious perception occurred at the expense of unconscious perception. Specifically, there was a right-hemisphere inferiority for the unconscious perception of negative information. Contrary to the predictions of the Right-Hemisphere Hypothesis, there were no hemispheric asymmetries for the perception of positive emotional information, thus suggesting that the Right-Hemisphere Hypothesis may not be applicable to all behavioral studies.     

When can we introspect accurately about mental processes?

Some theorists have suggested that the cognitive processes determining a person’s perforance in a given task are unconscious, making introspection a poor research tool for studying these processes. Others have argued that the relevant processes usually are consciously conrolled and can be detailed by asking the person to introspect. Here, a synthesis of these two positions, a dual-factor approach, is proposed. Some of the processes involved in achieving a cognitive goal, such as learning a new concept, are viewed as unconscious and automatic; howver, other processes are intentionally allocated conscious attention, in certain tasks, to accomlish othe goal. To illustrate this dual-factor position, evidence is presented in support of the view that when concept learning occurs solely by automatic frequency processing, introspective reports are inaccurate, but when the nature of the task prompts intentional hypothesis testing, introspective reports are accurate, revealing clues that subjects engage in a conscious hypothesisesting strategy.