Perception of facial expression depends on prior attention

Attending versus ignoring a stimulus can later determine how it will be affectively evaluated. Here, we asked whether attentional states could also modulate subsequent sensitivity to facial expressions of emotion. In a dual-task procedure, participants first rapidly searched for a gender-defined face among two briefly displayed neutral faces. Then a test face with the previously attended or ignored face’s identity was presented, and participants judged whether it was emotionally expressive (happy, angry, or fearful) or neutral. Intensity of expression in the test face was varied so that an expression detection threshold could be determined. When fearful or angry expressions were judged, expression sensitivity was worse for faces bearing the same identity as a previously ignored versus attended face. When happy expressions were judged, sensitivity was unaffected by prior attention. These data support the notion that the motivational value of stimuli may be reduced by processes associated with selective ignoring.     

Multiple systems for cognitive control: evidence from a hybrid prime-Simon task

Cognitive control resolves conflicts between appropriate and inappropriate response tendencies. Is this achieved by a unitary all-purpose conflict control system, or do independent subsystems deal with different aspects of conflicting information? In a fully factorial hybrid prime-Simon task, participants responded to the identity of targets displayed at different nominally irrelevant screen locations, preceded by nominally irrelevant, consciously or nonconsciously perceived primes. The response required by the target's identity could match or mismatch (a) the target's location, and (b) the prime's identity, resulting in potential conflict (a) across and (b) within stimulus domains. Conflict effects were investigated within and across trials. Results suggest that (i) nonconsciously perceived information elicits within-trial control, but--unlike consciously perceived information--no across-trial behavioral modulation; (ii) separate subsystems deal with conflicts arising from different stimulus domains; and (iii) occasional apparent interactions between domains reflect a particular difficulty in reactivating a just-discarded response (reactivation aversion effect, RAE).     

Consciousness, accessibility, and the mesh between psychology and neuroscience

How can we disentangle the neural basis of phenomenal consciousness from the neural machinery of the cognitive access that underlies reports of phenomenal consciousness? We see the problem in stark form if we ask how we can tell whether representations inside a Fodorian module are phenomenally conscious. The methodology would seem straightforward: Find the neural natural kinds that are the basis of phenomenal consciousness in clear cases--when subjects are completely confident and we have no reason to doubt their authority--and look to see whether those neural natural kinds exist within Fodorian modules. But a puzzle arises: Do we include the machinery underlying reportability within the neural natural kinds of the clear cases? If the answer is "Yes," then there can be no phenomenally conscious representations in Fodorian modules. But how can we know if the answer is "Yes"? The suggested methodology requires an answer to the question it was supposed to answer! This target article argues for an abstract solution to the problem and exhibits a source of empirical data that is relevant, data that show that in a certain sense phenomenal consciousness overflows cognitive accessibility. I argue that we can find a neural realizer of this overflow if we assume that the neural basis of phenomenal consciousness does not include the neural basis of cognitive accessibility and that this assumption is justified (other things being equal) by the explanations it allows.     

Evidence for a fixed capacity limit in attending multiple locations

A classic question concerns whether humans can attend multiple locations or objects at once. Although it is generally agreed that the answer to this question is “yes,” the limits on this ability are subject to extensive debate. According to one view, attentional resources can be flexibly allocated to a variable number of locations, with an inverse relationship between the number of selected locations and the quality of information processing at each location. Alternatively, these resources might be quantized in a “discrete” fashion that enables concurrent access to a small number of locations. Here, we report a series of experiments comparing these alternatives. In each experiment, we cued participants to attend a variable number of spatial locations and asked them to report the orientation of a single, briefly presented target. In all experiments, participants’ orientation report errors were well-described by a model that assumes a fixed upper limit in the number of locations that can be attended. Conversely, report errors were poorly described by a flexible-resource model that assumes no fixed limit on the number of locations that can be attended. Critically, we showed that these discrete limits were predicted by cue-evoked neural activity elicited before the onset of the target array, suggesting that performance was limited by selection processes that began prior to subsequent encoding and memory storage. Together, these findings constitute novel evidence supporting the hypothesis that human observers can attend only a small number of discrete locations at an instant.     

Dreams: an empirical way to settle the discussion between cognitive and non-cognitive theories of consciousness

Cognitive theories claim, whereas non-cognitive theories deny, that cognitive access is constitutive of phenomenology. Evidence in favor of non-cognitive theories has recently been collected by Block and is based on the high capacity of participants in partial-report experiments compared to the capacity of the working memory. In reply, defenders of cognitive theories have searched for alternative interpretations of such results that make visual awareness compatible with the capacity of the working memory; and so the conclusions of such experiments remain controversial. Instead of entering the debate between alternative interpretations of partial-report experiments, this paper offers an alternative line of research that could settle the discussion between cognitive and non-cognitive theories of consciousness. Here I relate the neural correlates of cognitive access to empirical research into the neurophysiology of dreams; cognitive access seems to depend on the activity of the dorsolateral prefrontal cortex. However, that area is strongly deactivated during sleep; a period when we entertain conscious experiences: dreams. This approach also avoids the classic objection that consciousness should be inextricably tied to reportability or it would fall outside the realm of science.     

No watershed for overflow: Recent work on the richness of consciousness

A familiar and enduring controversy surrounds the question of whether our phenomenal experience “overflows” availability to cognition: do we consciously see more than we can remember and report? Both sides to this debate have long sought to move beyond naïve appeals to introspection by providing empirical evidence for or against overflow. Recently, two notable studies—Bronfman, Brezis, Jacobson, and Usher (2014) and Vandenbroucke, Sligte, Fahrenfort, Ambroziak, and Lamme (2012)—have purported to provide compelling evidence in favor of overflow. Here I explain why the data from both studies are wholly consistent with a “no overflow” interpretation. Importantly, when framed purely in representational or informational terms, this “no overflow” interpretation agrees with the interpretations respectively offered by both Bronfman et al. (2014) and Vandenbroucke et al. (2012). The difference only emerges when additional assumptions are made concerning which representations correspond to elements in conscious experience. The assumptions made by overflow theorists are contentious and poorly motivated. However, challenging them simply reopens the original controversy. The upshot is a sobering moral: we still do not know how to move beyond appeals to naïve introspection in establishing the nature and limits of our ordinary experience.     

Open and closed cortico-subcortical loops: A neuro-computational account of access to consciousness in the distractor-induced blindness paradigm

How the brain decides which information to process ‘consciously’ has been debated over for decades without a simple explanation at hand. While most experiments manipulate the perceptual energy of presented stimuli, the distractor-induced blindness task is a prototypical paradigm to investigate gating of information into consciousness without or with only minor visual manipulation. In this paradigm, subjects are asked to report intervals of coherent dot motion in a rapid serial visual presentation (RSVP) stream, whenever these are preceded by a particular color stimulus in a different RSVP stream. If distractors (i.e., intervals of coherent dot motion prior to the color stimulus) are shown, subjects’ abilities to perceive and report intervals of target dot motion decrease, particularly with short delays between intervals of target color and target motion.We propose a biologically plausible neuro-computational model of how the brain controls access to consciousness to explain how distractor-induced blindness originates from information processing in the cortex and basal ganglia. The model suggests that conscious perception requires reverberation of activity in cortico-subcortical loops and that basal-ganglia pathways can either allow or inhibit this reverberation. In the distractor-induced blindness paradigm, inadequate distractor-induced response tendencies are suppressed by the inhibitory ‘hyperdirect’ pathway of the basal ganglia. If a target follows such a distractor closely, temporal aftereffects of distractor suppression prevent target identification. The model reproduces experimental data on how delays between target color and target motion affect the probability of target detection.     

Semantic priming,prime reportability,and retroactive priming are interdependent

In two experiments, semantic analysis of prime words was measured in terms of facilitation in naming a semantically related target word. Targets were degraded but gradually clarified until the subject named them. Subjects reported the prime after naming the target. Experiment 1 used semantic associates as primes at a 50-msec prime-target stimulus onset asynchrony (SOA). Experiment 2 used both semantic-associate and identity primes at a 1,000-msec prime-target SOA. Reported primes showed facilitation in both experiments, whereas unreported primes did not. It appears that primes that undergo enough analysis to facilitate target processing are also available for conscious report. However, retroactive priming in both experiments showed that target processing also had an impact on prime reportability. The interdependence of priming and prime reportability disallows a straightforward interpretation of the origin of the facilitation.     

Audiovisual identity perception from naturally-varying stimuli is driven by visual information

Identity perception often takes place in multimodal settings, where perceivers have access to both visual (face) and auditory (voice) information. Despite this, identity perception is usually studied in unimodal contexts, where face and voice identity perception are modelled independently from one another. In this study, we asked whether and how much auditory and visual information contribute to audiovisual identity perception from naturally-varying stimuli. In a between-subjects design, participants completed an identity sorting task with either dynamic video-only, audio-only or dynamic audiovisual stimuli. In this task, participants were asked to sort multiple, naturally-varying stimuli from three different people by perceived identity. We found that identity perception was more accurate for video-only and audiovisual stimuli compared with audio-only stimuli. Interestingly, there was no difference in accuracy between video-only and audiovisual stimuli. Auditory information nonetheless played a role alongside visual information as audiovisual identity judgements per stimulus could be predicted from both auditory and visual identity judgements, respectively. While the relationship was stronger for visual information and audiovisual information, auditory information still uniquely explained a significant portion of the variance in audiovisual identity judgements. Our findings thus align with previous theoretical and empirical work that proposes that, compared with faces, voices are an important but relatively less salient and a weaker cue to identity perception. We expand on this work to show that, at least in the context of this study, having access to voices in addition to faces does not result in better identity perception accuracy.     

Competing top-down processes in visual selection: evidence that selection by location is stronger than selection by color

The purpose of this study was to examine whether color and position information are functionally equivalent when observers are asked to select simultaneously on both dimensions. Observers were asked to report a letter of a given color from a given region of a briefly flashed letter array, then to report any additional letters they could recall from the stimulus set. Of the additional letters, more location letters were reported than were same-color or neutral letters. The results suggested that position information has priority over color information in top-down-guided visual selection.     

Perceptual consciousness overflows cognitive access

One of the most important issues concerning the foundations of conscious perception centers on the question of whether perceptual consciousness is rich or sparse. The overflow argument uses a form of 'iconic memory' to argue that perceptual consciousness is richer (i.e., has a higher capacity) than cognitive access: when observing a complex scene we are conscious of more than we can report or think about. Recently, the overflow argument has been challenged both empirically and conceptually. This paper reviews the controversy, arguing that proponents of sparse perception are committed to the postulation of (i) a peculiar kind of generic conscious representation that has no independent rationale and (ii) an unmotivated form of unconscious representation that in some cases conflicts with what we know about unconscious representation.     

The extraction of information from visual persistence.

Seven-letter targets were flashed for 50 msec and followed by either a blank adapting field (persisting representation of the stimulus fully available) or a series of continuous cycles of target and mask until the cumulative duration of the target matched the estimated duration of visual persistence (stimulus physically present for same interval as representation). The reportability of information from the targets in the latter case was only 50% that in the former. The interpretation is that visual persistence is an active, continuously operating process rather than a passive neural copy of the stimulus.     

Change blindness and priming: When it does and does not occur

In a series of three experiments, we explored the nature of implicit representations in change blindness (CB). Using 3 x 3 letter arrays, we asked subjects (Ss) to locate changes in paired arrays separated by 80 ms ISIs, in which one, two or three letters of a row in the second array changed. In one testing version, a tone followed the second array, signaling a row for partial report (PR). In the other version, no PR was required. After Ss reported whether a change had been detected and the PR had been completed (if required), they were asked to identify a degraded letter trigram that was either novel, or from a previously shown row (repetition priming). Our findings indicate that when CB occurs, both the pre-change and post-change stimulus information primes despite its unavailability to consciousness. Surprisingly, findings also indicate that when change detection occurs only the post-change information primes.     

动物的元认知能力研究综述

“知道自己知道,知道自己不知道”,这种“元认知”能力被看成是人类最复杂的认知能力之一;目前学者们对人类的元认知能力进行了比较深入地研究,这时人们不禁会问:这种普遍存在于人类身上的基本认知能力,在动物身上是否也同样存在呢?一些学者做了实验研究加以考察,并提出两个相反的观点;这个领域的研究也在这样的争论中不断发展,通过对动物元认知模式的研究,科学家可以回答这一问题并试图描绘出动物进化的图谱,以及认知因素在物种进化中的作用,更重要的是,它为我们从物种学角度探讨意识和自我意识的起源提供了很好的思考角度。     

The effect of attending to motor overflow on its voluntary inhibition in young and older adults

Motor overflow refers to involuntary movement or muscle activity coinciding with voluntary movement. We examined whether 16 young adults (18-30 years) and 16 older adults (50-80 years) could voluntarily inhibit overflow. Participants performed a finger pressing task, exerting 50% of their maximal force. Overflow was concurrently recorded in the non-task hand. In the first condition, participants were not made aware of their motor overflow. Then participants, though informed of it, were asked to ignore their overflow. Finally, participants were requested to inhibit overflow with, and then without visual feedback, or vice versa. Overflow was exacerbated when older adults were unaware of it, and was reduced once they were informed. For young adults there was no significant difference between these conditions. Both Age Groups could significantly reduce overflow when so requested, independent of visual feedback. Thus motor overflow can be modulated by higher order cognitive control with directed attention.     

Subjective visibility report is facilitated by conscious predictions only

Predictions in the visual domain have been shown to modulate conscious access. Yet, little is known about how predictions may do so and to what extent they need to be consciously implemented to be effective. To address this, we administered an attentional blink (AB) task in which target 1 (T1) identity predicted target 2 (T2) identity, while participants rated their perceptual awareness of validly versus invalidly predicted T2s (Experiment 1 & 2) or reported T2 identity (Experiment 3). Critically, we tested the effects of conscious and non-conscious predictions, after seen and unseen T1s, on T2 visibility. We found that valid predictions increased subjective visibility reports and discrimination of T2s, but only when predictions were generated by a consciously accessed T1, irrespective of the timing at which the effects were measured (short vs. longs lags). These results further our understanding of the intricate relationship between predictive processing and consciousness.     

Speaker information affects false recognition of unstudied lexical-semantic associates

Recognition of and memory for a spoken word can be facilitated by a prior presentation of that word spoken by the same talker. However, it is less clear whether this speaker congruency advantage generalizes to facilitate recognition of unheard related words. The present investigation employed a false memory paradigm to examine whether information about a speaker’s identity in items heard by listeners could influence the recognition of novel items (critical intruders) phonologically or semantically related to the studied items. In Experiment 1, false recognition of semantically associated critical intruders was sensitive to speaker information, though only when subjects attended to talker identity during encoding. Results from Experiment 2 also provide some evidence that talker information affects the false recognition of critical intruders. Taken together, the present findings indicate that indexical information is able to contact the lexical-semantic network to affect the processing of unheard words.     

Where to look first for an explanation of induction with uncertain categories

Recent research has examined how people predict unobserved features of an object when its category membership is ambiguous. The debate has focused on whether predictions are based solely on information from the most likely category, or whether information from other possible categories is also used. In the present experiment, we compared these category-based approaches with feature conjunction reasoning, where predictions are based on a comparison among exemplars (rather than categories) that share features with a target object. Reasoning strategies were assessed by examining patterns of feature prediction and by using an eye gaze measure of attention during induction. The main findings were (1) the majority of participants used feature conjunction rather than categorical strategies, (2) people predominantly gazed at the exemplars that were most similar to the target object, and (3) although people gazed most at the most probable category to which an object could belong, they also attended to other plausible category alternatives during induction. These findings question the extent to which category-based reasoning is used for induction when category membership is uncertain.     

Imagery and overflow: We see more than we report

The question of whether our conscious experience is rich or sparse remains an enduring controversy in philosophy. The “overflow” account argues that perceptual consciousness is far richer than cognitive access: when perceiving a complex scene, subjects see more than they can report. This paper draws on aphantasia (the condition of absent voluntary imagery) to propose a new argument in favor of overflow. First, it shows that opponents of overflow explain subjects’ performance in a change detection paradigm by appealing to a type of “internal imagery.” Second, it provides empirical evidence to demonstrate that aphantasics are incapable of generating this imagery. However, aphantasics perform equally well in this task; and so the no-overflow account fails to explain their performance. This means that proponents of this view are committed to an unsupported view of perception.     

Seeing is believing: Utilization of subliminal symbols requires a visible relevant context

Sensory input that is not available for conscious report can still affect our behavior. Recent findings suggest that such subliminal information has the potency to influence behavior in a way that is dependent on the observer’s current intentions. Here, we investigate whether conscious observation of stimulus relevance provides an incentive for the utilization of nonconscious stimuli. We manipulated the predictive power of directional cues to selectively affect the incentive to utilize them for a subsequent target detection task. Central arrow cues rendered invisible by interocular suppression elicited a facilitatory cuing effect, but only when intermixed with visible arrow cues that were highly predictive with respect to (i.e., 80 % congruent with) the subsequent target location. When the visible cues were nonpredictive (50 % congruent), no subliminal cuing effect was found. An analysis of learning effects corroborates these findings; Cuing effects elicited by both visible and invisible cues increased over the course of the experiment, but only when intermixed visible cues were highly predictive. In a second experiment, we demonstrated that the intrinsic relevance of invisible cues (either 50 % or 100 % congruent) has no effect on the utilization of visible cues. We conclude that conscious perception is required to make statistical inferences about the relevance of symbolic cues. Once statistical information is extracted consciously, it affects subsequent nonconscious processing in a way that fits the current context. Accordingly, one of the possible functions of consciousness could be to extract general rules out of the conscious information, to provide guidelines for future behavior.