Differential processing of invisible congruent and incongruent scenes: A case for unconscious integration

Integration is held to be a key feature of conscious awareness. Some even argue that the latter cannot occur without the former. We tested this claim by presenting masked scenes depicting a person performing an action with a congruent or an incongruent object (e.g., a man pouring coffee into a mug or into a roll of toilet paper). The masked scenes were then followed by briefly flashed targets that again included a congruent or an incongruent object, and subjects were asked to judge targets' congruency as fast as possible. Reaction times (RTs) for targets preceded by perceptually invisible scenes that included an incongruent object were longer than RTs for targets that were preceded by congruent images. This implicit measure suggests that subjects processed certain relations between the object and its background—or at least between the object and another object in the scene—despite being unaware of either. Subjective and objective measures confirmed the invisibility of the masked scenes, ruling out partial awareness. These results suggest that incongruency between scene elements can be unconsciously processed even at impoverished presentation conditions, with reduced contrast and exposure durations as short as 33 ms. They provide evidence for ongoing contextual influences of unseen stimuli on the processing of a subsequent target

“Me & My Brain”: Exposing Neuroscienceʼs Closet Dualism

Our intuitive concept of the relations between brain and mind is increasingly challenged by the scientific world view. Yet, although few neuroscientists openly endorse Cartesian dualism, careful reading reveals dualistic intuitions in prominent neuroscientific texts. Here, we present the "double-subject fallacy": treating the brain and the entire person as two independent subjects who can simultaneously occupy divergent psychological states and even have complex interactions with each other-as in "my brain knew before I did." Although at first, such writing may appear like harmless, or even cute, shorthand, a closer look suggests that it can be seriously misleading. Surprisingly, this confused writing appears in various cognitive-neuroscience texts, from prominent peer-reviewed articles to books intended for lay audience. Far from being merely metaphorical or figurative, this type of writing demonstrates that dualistic intuitions are still deeply rooted in contemporary thought, affecting even the most rigorous practitioners of the neuroscientific method. We discuss the origins of such writing and its effects on the scientific arena as well as demonstrate its relevance to the debate on legal and moral responsibility

Detecting falsehood relies on mismatch detection between sentence components

How do people process and evaluate falsehood of sentences? Do people need to compare presented information with the correct answer to determine that a sentence is false, or do they rely on a mismatch between presented sentence components? To illustrate, when confronted with the false sentence ‘trains run on highways’, does one need to know that trains do not run on highways or does one need to know that trains run on tracks to reject the sentence as false? To investigate these questions, participants were asked to validate sentences that were preceded by images (Experiments 1-3) conveying a truth-congruent or a falsehood-congruent component of the sentence (e.g., an image of tracks/highway preceding the sentence ‘trains run on tracks/highways’) or by words (Experiment 4) that were either sentence-congruent, truth-congruent, or both (e.g., the word ‘train/tracks’ preceding the sentence ‘trains run on tracks/highways’). Results from four experiments showed that activating sentence-congruent concepts facilitates validation for both false and true sentences but that activating truth-congruent concepts did not aid the validation of false sentences. The present findings suggest that a detection of falsehood relies on a mismatch detection between sentence’s components, rather than on the activation of true content in the context of a particular sentence

Theories of Consciousness and a Life Worth Living

What is it that makes a life valuable? A popular view is that life’s moral worth depends in some way on its relationship to consciousness or subjective experience. But a practical application of this view requires the ability to test for consciousness, which is currently lacking. Here, we examine how theories of consciousness (ToCs) can help do so, focusing especially on difficult cases where the answer is not clear (e.g. fetuses, nonhuman animals, unresponsive brain-injured patients, and advanced artificial systems). We consider five major ToCs and what predictions they offer: Integrated information theory, Higher-Order Thought Theory, Recurrent Processing Theory, Global Neuronal Workspace Theory, and Attention Schema Theory. We highlight the important distinction between the capacity and potential for consciousness and use it to explore the limitations in our ability to draw firm conclusions regarding an entity\u27s consciousness on the basis of each theory

Multisensory Integration in Complete Unawareness: Evidence From Audiovisual Congruency Priming

Multisensory integration is thought to require conscious perception. Although previous studies have shown that an invisible stimulus could be integrated with an audible one, none have demonstrated integration of two subliminal stimuli of different modalities. Here, pairs of identical or different audiovisual target letters (the sound /b/ with the written letter “b” or “m,” respectively) were preceded by pairs of masked identical or different audiovisual prime digits (the sound /6/ with the written digit “6” or “8,” respectively). In three experiments, awareness of the audiovisual digit primes was manipulated, such that participants were either unaware of the visual digit, the auditory digit, or both. Priming of the semantic relations between the auditory and visual digits was found in all experiments. Moreover, a further experiment showed that unconscious multisensory integration was not obtained when participants did not undergo prior conscious training of the task. This suggests that following conscious learning, unconscious processing suffices for multisensory integration

Human single neuron activity precedes emergence of conscious perception

Identifying the neuronal basis of spontaneous changes in conscious experience in the absence of changes in the external environment is a major challenge. Binocular rivalry, in which two stationary monocular images lead to continuously changing perception, provides a unique opportunity to address this issue. We studied the activity of human single neurons in the medial temporal and frontal lobes while patients were engaged in binocular rivalry. Here we report that internal changes in the content of perception are signaled by very early (~-2000 ms) nonselective medial frontal activity, followed by selective activity of medial temporal lobe neurons that precedes the perceptual change by ~1000 ms. Such early activations are not found for externally driven perceptual changes. These results suggest that a medial fronto-temporal network may be involved in the preconscious internal generation of perceptual transitions

Neural precursors of decisions that matter—an ERP study of deliberate and arbitrary choice

The readiness potential (RP)—a key ERP correlate of upcoming action—is known to precede subjects' reports of their decision to move. Some view this as evidence against a causal role for consciousness in human decision-making and thus against free-will. But previous work focused on arbitrary decisions—purposeless, unreasoned, and without consequences. It remains unknown to what degree the RP generalizes to deliberate, more ecological decisions. We directly compared deliberate and arbitrary decision-making during a $1000-donation task to non-profit organizations. While we found the expected RPs for arbitrary decisions, they were strikingly absent for deliberate ones. Our results and drift-diffusion model are congruent with the RP representing accumulation of noisy, random fluctuations that drive arbitrary—but not deliberate—decisions. They further point to different neural mechanisms underlying deliberate and arbitrary decisions, challenging the generalizability of studies that argue for no causal role for consciousness in decision-making to real-life decisions

On Reporting the Onset of the Intention to Move

In 1965, Hans Kornhuber and Luder Deecke made a discovery that greatly influenced the study of voluntary action. Using electroencephalography (EEG), they showed that when aligning some tens of trials to movement onset and averaging, a slowly decreasing electrical potential emerges over central regions of the brain. It starts 1 second ( s) or so before the onset of the voluntary action1 and continues until shortly after the action begins. They termed this the Bereitschaftspotential, or readiness potential (RP; Kornhuber & Deecke, 1965).2 This became the first well-established neural marker of voluntary action. In that, the RP allowed for more objective research on voluntary action rather than its previous dependence on subjective introspection. Two decades later, the RP captured the attention of the wider neuroscience community as well as of philosophers, legal scholars, and laypeople. This is because it was associated with a key question in the debate on free will: Is human voluntary action caused by the conscious intention to act? Or does the conscious experience only follow unconscious neural activity, which is the true origin of that action, and over which humans have only-limited immediate control?https://digitalcommons.chapman.edu/psychology_books/1019/thumbnail.jp

Does It Matter Whether You or Your Brain Did It? An Empirical Investigation of the Influence of the Double Subject Fallacy on Moral Responsibility Judgments

Despite progress in cognitive neuroscience, we are still far from understanding the relations between the brain and the conscious self. We previously suggested that some neuroscientific texts that attempt to clarify these relations may in fact make them more difficult to understand. Such texts—ranging from popular science to high-impact scientific publications—position the brain and the conscious self as two independent, interacting subjects, capable of possessing opposite psychological states. We termed such writing ‘Double Subject Fallacy’ (DSF). We further suggested that such DSF language, besides being conceptually confusing and reflecting dualistic intuitions, might affect people’s conceptions of moral responsibility, lessening the perception of guilt over actions. Here, we empirically investigated this proposition with a series of three experiments (pilot and two preregistered replications). Subjects were presented with moral scenarios where the defendant was either (1) clearly guilty, (2) ambiguous, or (3) clearly innocent while the accompanying neuroscientific evidence about the defendant was presented using DSF or non-DSF language. Subjects were instructed to rate the defendant’s guilt in all experiments. Subjects rated the defendant in the clearly guilty scenario as guiltier than in the two other scenarios and the defendant in the ambiguously described scenario as guiltier than in the innocent scenario, as expected. In Experiment 1 (N = 609), an effect was further found for DSF language in the expected direction: subjects rated the defendant less guilty when the neuroscientific evidence was described using DSF language, across all levels of culpability. However, this effect did not replicate in Experiment 2 (N = 1794), which focused on different moral scenario, nor in Experiment 3 (N = 1810), which was an exact replication of Experiment 1. Bayesian analyses yielded strong evidence against the existence of an effect of DSF language on the perception of guilt. Our results thus challenge the claim that DSF language affects subjects’ moral judgments. They further demonstrate the importance of good scientific practice, including preregistration and—most critically—replication, to avoid reaching erroneous conclusions based on false-positive results

Neural precursors of decisions that matter—an ERP study of deliberate and arbitrary choice

The readiness potential (RP)—a key ERP correlate of upcoming action—is known to precede subjects' reports of their decision to move. Some view this as evidence against a causal role for consciousness in human decision-making and thus against free-will. But previous work focused on arbitrary decisions—purposeless, unreasoned, and without consequences. It remains unknown to what degree the RP generalizes to deliberate, more ecological decisions. We directly compared deliberate and arbitrary decision-making during a $1000-donation task to non-profit organizations. While we found the expected RPs for arbitrary decisions, they were strikingly absent for deliberate ones. Our results and drift-diffusion model are congruent with the RP representing accumulation of noisy, random fluctuations that drive arbitrary—but not deliberate—decisions. They further point to different neural mechanisms underlying deliberate and arbitrary decisions, challenging the generalizability of studies that argue for no causal role for consciousness in decision-making to real-life decisions