Involuntary polymodal imagery involving olfaction, audition, touch, taste, and vision.

Percepts and urges often enter consciousness involuntarily. The Reflexive Imagery Task (RIT) reveals how high-level cognitions, too, can enter consciousness involuntarily. In the task, the eliciting stimuli are visual (e.g., picture of a cat), and the involuntary imagery is verbal (e.g., the subvocalization "cat"). The generalizability of the RIT effect has been questioned because verbal imagery is an easily elicited form of imagery. Do such effects arise for other kinds of imagery? It is known that imagery is more elicitable in some senses (e.g., vision) than in other senses (e.g., olfaction). We found such differences in an RIT in which food items were presented as orthographic stimuli or as drawings. Although subjects were instructed to suppress mental imagery, involuntary imagery still arose: Olfactory (effect in ∼40% of trials), taste (∼54%), touch (∼60%), and visual/auditory (∼79%). Of theoretical import, effects were comparable when the eliciting stimuli were orthographs or visual objects.

Conscious contents as reflexive processes: Evidence from the habituation of high-level cognitions.

Reflexes are often insuppressible, predictable, and susceptible to external control. In contrast, conscious thoughts have been regarded as whimsical, 'offline,' and shielded from external control. Recent advances suggest that conscious thoughts are more reflex-like and susceptible to external control than previously thought. In one paradigm, high-level conscious thoughts (subvocalizations) are triggered by external control, as a function of external stimuli and experimenter-induced action sets. It has been hypothesized that these conscious contents are activated involuntarily and in a reflex-like manner. If such is the case, then these activations should possess a well-known property of the reflex: habituation. Accordingly, we found that involuntary high-level cognitions (subvocalizations) habituated (i.e., were less likely to arise) after repeated stimulation. As in the case of the habituation of a reflex, this novel effect was stimulus-specific. We discuss the implications of this finding for theories about consciousness and about psychopathological phenomena involving undesired, involuntary cognitions.

EEG Correlates of Involuntary Cognitions in the Reflexive Imagery Task.

The Reflexive Imagery Task (RIT) reveals that the activation of sets can result in involuntary cognitions that are triggered by external stimuli. In the basic RIT, subjects are presented with an image of an object (e.g., CAT) and instructed to not think of the name of the object. Involuntary subvocalizations of the name (the RIT effect) arise on roughly 80% of the trials. We conducted an electroencephalography (EEG) study to explore the neural correlates of the RIT effect. Subjects were presented with one object at a time in one condition and two objects simultaneously in another condition. Five regions were defined by electrode sites: frontal (F3-F4), parietal (P3-P4), temporal (T3-T4), right hemisphere (F4-P4), and left hemisphere (F3-P3). We focused on the alpha (8-13 Hz), beta (13-30 Hz), delta (0.01-4 Hz), and theta (4-8 Hz) frequencies.

The reflexive imagery task: An experimental paradigm for neuroimaging.

High-level cognitions can be triggered into consciousness through the presentation of external stimuli and the activation of certain action sets. These activations arise in a manner that is involuntary, systematic and nontrivial. For example, in the Reflexive Imagery Task (RIT), subjects are presented with visual objects and instructed to not think of the names of the objects. Involuntary subvocalizations arise on roughly 80% of the trials. We review the findings from this paradigm, discuss neural findings that are relevant to the RIT, and present new data that further corroborate the reliability and robustness of the RIT, a paradigm that could be coupled with neuroimaging technologies. We developed an RIT variant in which two, non-focal objects are presented simultaneously. In previous RITs, visual objects were presented only one at a time, in the center of the screen, and subjects were instructed to focus on the center of the screen, where these objects were presented. Replicating the RIT effect, involuntary subvocalizations still occurred on a high proportion of trials (M = 0.78). An RIT effect arose for both objects on a considerable proportion of the trials (M = 0.35). These findings were replicated in a second experiment having a different sample of subjects. Our findings are relevant to many subfields of neuroscience (e.g., the study of high-level mental processes, attention, imagery and action control).

The reflexive imagery task: An experimental paradigm for neuroimaging.

High-level cognitions can be triggered into consciousness through the presentation of external stimuli and the activation of certain action sets. These activations arise in a manner that is involuntary, systematic and nontrivial. For example, in the Reflexive Imagery Task (RIT), subjects are presented with visual objects and instructed to not think of the names of the objects. Involuntary subvocalizations arise on roughly 80% of the trials. We review the findings from this paradigm, discuss neural findings that are relevant to the RIT, and present new data that further corroborate the reliability and robustness of the RIT, a paradigm that could be coupled with neuroimaging technologies. We developed an RIT variant in which two, non-focal objects are presented simultaneously. In previous RITs, visual objects were presented only one at a time, in the center of the screen, and subjects were instructed to focus on the center of the screen, where these objects were presented. Replicating the RIT effect, involuntary subvocalizations still occurred on a high proportion of trials (M = 0.78). An RIT effect arose for both objects on a considerable proportion of the trials (M = 0.35). These findings were replicated in a second experiment having a different sample of subjects. Our findings are relevant to many subfields of neuroscience (e.g., the study of high-level mental processes, attention, imagery and action control).

Mood effects on the ERP processing of emotional intensity in faces: a P3 investigation with depressed students.

This study examined mood-relevant emotion processing in depression using event-related potentials (ERPs). Cognition in depression has been characterized as having attention and memory biases for negative (or mood relevant) information and away from positive (or mood incongruent) information, however, the time course and specificity of this processing during the perception of emotional expressions is not well known. In order to index specific information processing stages a visual oddball task with facial stimuli was utilized, with neutral expressions as the standard and targets varying on valence (happy and fear) and intensity (40%, 70% or 100% emotive) dimensions. Participants were 36 university students grouped according to their BDI-II scores; 18 non-depressed controls (BDI-IIor=15, M=25.5), age- and sex-matched between groups. Mixed model ANOVAs revealed interactions between control and depressed participants with happy and fearful stimuli showing significantly reduced P3 amplitudes and P3 latencies for happy faces as well as significantly delayed P3 latencies specifically for 40% happy faces in depressed participants. These findings are interpreted as evidence for a diminished cognitive processing ability during emotion discrimination for low-intensity mood incongruous (happy) faces in depression.

Metacognition of Working Memory Performance: Trial-by-Trial Subjective Effects from a New Paradigm.

Investigators have begun to examine the fleeting urges and inclinations that subjects experience when performing tasks involving response interference and working memory. Building on this research, we developed a paradigm in which subjects, after learning to press certain buttons when presented with certain letters, are presented with two action-related letters (the memoranda) but must withhold responding (4 s) until cued to emit the response associated with only one of the two letters. In the Congruent condition, the action corresponds to the cue (e.g., memoranda = AB, cue = B, response = B); in the Incongruent condition, the action corresponds to the other item of the memoranda (e.g., memoranda = AB, cue = B, response = A). After each trial, subjects inputted a rating regarding their subjectively experienced "urge to err" on that trial. These introspection-based data revealed that, as found in previous research, urges to err were strongest for incongruent trials. Our findings reveal, first, that subjects can successfully perform this new task, even though it is more complex than that of previous studies, and second, that, in this new paradigm, reliable subjective, metacognitive data can be obtained on a trial-by-trial basis. We hope that our novel paradigm will serve as a foundation for future experimental projects on the relationship between working memory performance and consciousness-an under-explored nexus whose investigation is likely to reveal insights about working memory, cognitive control, and metacognition.

Internally generated conscious contents: interactions between sustained mental imagery and involuntary subvocalizations.

The conscious field includes not only representations about external stimuli (e.g., percepts), but also conscious contents associated with internal states, such as action-related intentions (e.g., urges). Although understudied, the latter may provide unique insights into the nature of consciousness. To illuminate these phenomena, in a new experimental paradigm [Reflexive Imagery Task (RIT)], participants were instructed to not subvocalize the names of visually-presented objects. Each object was presented for 10 s on a screen. Participants indicated whenever they involuntarily subvocalized the object name. Research has revealed that it is difficult to suppress such subvocalizations, which occur on over 80% of the trials. Can the effect survive if one intentionally generates a competing (internally-generated) conscious content? If so, this would suggest that intentional and unintentional contents can co-exist simultaneously in consciousness in interesting ways. To investigate this possibility, in one condition, participants were instructed to reiteratively subvocalize a speech sound ("da, da, da") throughout the trial. This internally generated content is self-generated and intentional. Involuntary subvocalizations of object names still arose on over 80% of the trials. One could hypothesize that subvocalizations occurred because of the pauses between the intended speech sounds, but this is inconsistent with the observation that comparable results arose even when participants subvocalized a continuous, unbroken hum ("daaa….") throughout the trial. Regarding inter-content interactions, the continuous hum and object name seem to co-exist simultaneously in consciousness. This intriguing datum requires further investigation. We discuss the implications of this new paradigm for the study of internally-generated conscious contents.

The olfactory system as the gateway to the neural correlates of consciousness.

How consciousness is generated by the nervous system remains one of the greatest mysteries in science. Investigators from diverse fields have begun to unravel this puzzle by contrasting conscious and unconscious processes. In this way, it has been revealed that the two kinds of processes differ in terms of the underlying neural events and associated cognitive mechanisms. We propose that, for several reasons, the olfactory system provides a unique portal through which to examine this contrast. For this purpose, the olfactory system is beneficial in terms of its (a) neuroanatomical aspects, (b) phenomenological and cognitive/mechanistic properties, and (c) neurodynamic (e.g., brain oscillations) properties. In this review, we discuss how each of these properties and aspects of the olfactory system can illuminate the contrast between conscious and unconscious processing in the brain. We conclude by delineating the most fruitful avenues of research and by entertaining hypotheses that, in order for an olfactory content to be conscious, that content must participate in a network that is large-scale, both in terms of the neural systems involved and the scope of information integration.

Effect of bilateral eye movements on frontal interhemispheric gamma EEG coherence: implications for EMDR therapy.

The use of bilateral eye movements (EMs) is an important component of Eye Movement Desensitization and Reprocessing (EMDR) therapy for posttraumatic stress disorder. The neural mechanisms underlying EMDR remain unclear. However, prior behavioral work looking at the effects of bilateral EMs on the retrieval of episodic memories suggests that the EMs enhance interhemispheric interaction. The present study examined the effects of the EMs used in EMDR on interhemispheric electroencephalogram coherence. Relative to noneye-movement controls, engaging in bilateral EMs led to decreased interhemispheric gamma electroencephalogram coherence. Implications for future work on EMDR and episodic memory are discussed.