Joseph Glicksohn

The influence of task difficulty and external tempo on subjective time estimation.

Ninety-six subjects were asked to estimate durations of either “empty” or “filled” intervals during which they performed verbal tasks at three levels of difficulty. The verbal tasks were performed under three conditions of external rhythmic stimulation: fast, slow, and no external tempo. It was found that subjective time estimations were a decreasing function of task difficulty, and that durations for “empty” intervals were estimated to be longer than those for “filled” intervals. A relationship between external tempo and subjective time estimation was found. Longest time estimates were obtained under fast external tempo, and shortest time estimates were obtained under slow external tempo. Time estimates under the condition of no external tempo were found to be intermediate. The findings were interpreted as supporting a cognitive timer model of subjective time estimation.

Mindfulness-induced changes in gamma band activity – Implications for the default mode network, self-reference and attention

OBJECTIVE There is a growing scientific interest in mindfulness meditation (MM), yet its underlying neurophysiological mechanism is still uncertain. We investigated whether MM affects self-referential processing, associated with default mode network (DMN), either as short (state) - or long-term (trait) effects. METHODS Three levels of MM expertise were compared with controls (n=12 each) by electroencephalography (EEG). RESULTS DMN deactivation was identified during the transition from resting state to a time production task, as lower gamma (25-45 Hz) power over frontal and midline regions. MM practitioners exhibited a trait lower frontal gamma activity, related to narrative self-reference and DMN activity, as well as producing longer durations, these being negatively correlated with frontal gamma activity. Additionally, we found state increases in posterior gamma power, suggesting increased attention and sensory awareness. MM proficiency did not affect the results. CONCLUSIONS Gamma power over frontal midline areas reflects DMN activity. MM practitioners exhibit lower trait frontal gamma activity, as well as a state and trait increases in posterior gamma power, irrespective of practice proficiency. SIGNIFICANCE First, the DMN can be studied non-invasively by EEG. Second, MM induces from the early stages of practice neuroplasticity in self-referential and attentional networks.

Auditory inattention in right-hemisphere-damaged patients with and without visual neglect

Fifteen right-hemisphere-damaged patients, eight with- and seven without visual neglect (N+ and N-, respectively), were assessed for the presence of auditory neglect using free-field bilateral simultaneous stimulation (BSS) and pseudorandom unilateral stimulation. Eight healthy subjects served as controls. Both N+ and N- groups extinguished left-sided sound stimuli in the BSS condition. N+ (but not N-) patients showed a right-side advantage in sound localization and were inferior, compared to normal individuals, in their ability to localize unilaterally administered sounds on the left side. Blindfolding significantly improved the localization performance. In a task demanding stimulus identification, both N+ and N- groups performed abnormally when auditory stimuli came from the left. Free-field stimulation is thus an adequate technique for the detection of auditory neglect. The results are consistent with the notion that left-sided neglect reflects a pathologically exaggerated attentional bias towards the right in normal individuals.

Belief in the paranormal and subjective paranormal experience

Abstract The underlying experiential base for belief in the paranormal is the focus of the present three studies, employing students ( N = 72), schoolchildren ( N = 20) and a select group of subjects interested in the paranormal ( N = 33). A survey questionnaire tapping the incidence of occurrence of various types of subjective experience, and in particular the hypnagogic state, the hypnopompic state, the state of lucid dreaming and the out-of-the-body experience was one measure. A second concerned paranormal experience and paranormal belief. The Sensation Seeking Scale, Form IV (Zuckerman, 1979) and the Absorption Scale (Tellegen, 1982) were also employed. As hypothesized, degree of paranormal belief was positively correlated with subjective paranormal experience, and the latter was positively correlated with frequency of incidence of at least one altered state of consciousness (ASC) and with degree of absorption. Implications were drawn regarding the etiology of paranormal belief, and extended with reference to delusionary belief systems in pathological ASCs.

Personality, cognitive style and assortative mating

We investigated the degree of assortative mating among married couples, in terms of both personality (the Eysenckian Big Three and sensation seeking) and cognitive style (field dependence-independence; FDI). We found sizable assortative mating (0.25≤r≤0.29, p<0.05) for three dimensions of sensation seeking, namely experience seeking (ES), disinhibition (Dis) and boredom susceptibility (BS), all implicating an impulsive mode of sensation seeking. This stands in marked contrast to the Eysenckian Big Three, for which there does not seem to be assortative mating. We also found sizable assortative mating for FDI (r=0.38). We analyze and discuss these findings with respect to such factors as age, length of relationship, lie scores, the formation of pseudo couples, the assessment of profile similarity and match-mismatch in FDI.

Embedding sensation seeking within the big three

Abstract While Sensation Seeking is a construct which loads on both Extraversion (E) and Psychoticism (P), it is not clear whether Sensation Seeking can be reduced to E and P and whether all of its subfactors necessarily load on the same factor(s). We therefore decided to investigate the relationship among these. The 682 participants comprised a heterogeneous sample. They completed the SSS (Form V) and then the EPQ-R-S (short version of the revised EPQ). Factor analysis of the EPQ-R-S revealed simple structure, with 46 of the 48 items being correctly located on their respective factors. Analysis of the SSS also revealed simple structure, with 31 of the 40 items being correctly located on their respective factors. When the items from the EPQ-R-S and SSS were combined in one analysis, using a 4-factor constraint, we could identify these as follows: The first factor entailing items from 3 SSS scales (ES, Dis and BS) and 2 EPQ scales (L and P), could be referred to as Impulsive Unsocialized Sensation Seeking (P-ImpUSS). The second was identified as N; the third was identified as E; and the fourth as TAS. Thus it is P which loads on P-ImpUSS, with TAS being distinct from the latter.

Alterations in the sense of time, space, and body in the mindfulness-trained brain: a neurophenomenologically-guided MEG study

Meditation practice can lead to what have been referred to as “altered states of consciousness.”One of the phenomenological characteristics of these states is a joint alteration in the sense of time, space, and body. Here, we set out to study the unique experiences of alteration in the sense of time and space by collaborating with a select group of 12 long-term mindfulness meditation (MM) practitioners in a neurophenomenological setup, utilizing first-person data to guide the neural analyses. We hypothesized that the underlying neural activity accompanying alterations in the sense of time and space would be related to alterations in bodily processing. The participants were asked to volitionally bring about distinct states of “Timelessness” (outside time) and “Spacelessness” (outside space) while their brain activity was recorded by MEG. In order to rule out the involvement of attention, memory, or imagination, we used control states of “Then” (past) and “There” (another place). MEG sensors evidencing alterations in power values were identified, and the brain regions underlying these changes were estimated via spatial filtering (beamforming). Particularly, we searched for similar neural activity hypothesized to underlie both the state of “Timelessness” and “Spacelessness.” The results were mostly confined to the theta band, and showed that: (1) the “Then”/“There” overlap yielded activity in regions related to autobiographic memory and imagery (right posterior parietal lobule (PPL), right precentral/middle frontal gyrus (MFG), bilateral precuneus); (2) “Timelessness”/“Spacelessness” conditions overlapped in a different network, related to alterations in the sense of the body (posterior cingulate, right temporoparietal junction (TPJ), cerebellum); and (3) phenomenologically-guided neural analyses enabled us to dissociate different levels of alterations in the sense of the body. This study illustrates the utility of employing experienced contemplative practitioners within a neurophenomenological setup for scientifically characterizing a self-induced altered sense of time, space and body, as well as the importance of theta activity in relation with these altered states.

Mindfulness-induced selflessness: a MEG neurophenomenological study

Contemporary philosophical and neurocognitive studies of the self have dissociated two distinct types of self-awareness: a “narrative” self-awareness (NS) weaving together episodic memory, future planning and self-evaluation into a coherent self-narrative and identity, and a “minimal” self-awareness (MS) focused on present momentary experience and closely tied to the sense of agency and ownership. Long-term Buddhist meditation practice aims at realization of a “selfless” mode of awareness (SL), where identification with a static sense of self is replaced by identification with the phenomenon of experiencing itself. NS-mediating mechanisms have been explored by neuroimaging, mainly fMRI, implicating prefrontal midline structures, but MS processes are not well characterized and SL even less so. To this end we tested 12 long-term mindfulness meditators using a neurophenomenological study design, incorporating both magnetoencephalogram (MEG) recordings and first person descriptions. We found that (1) NS attenuation involves extensive frontal, and medial prefrontal gamma band (60–80 Hz) power decreases, consistent with fMRI and intracranial EEG findings; (2) MS attenuation is related to beta-band (13–25 Hz) power decreases in a network that includes ventral medial prefrontal, medial posterior and lateral parietal regions; and (3) the experience of selflessness is linked to attenuation of beta-band activity in the right inferior parietal lobule. These results highlight the role of dissociable frequency-dependent networks in supporting different modes of self-processing, and the utility of combining phenomenology, mindfulness training and electrophysiological neuroimaging for characterizing self-awareness.

Changes of brain anatomy in patients with posttraumatic stress disorder: A pilot magnetic resonance imaging study

No abnormalities in magnetic resonance images were recorded in patients with posttraumatic stress disorder other than an increased incidence (50%) of a small cleft in the callosal-septal interface, a cavum of the septum pellucidum. A similar grade of cavum was obtained in 14% of normal volunteers matched for age, socioeconomic background, and military experience. The cavum is believed to have antedated the disorder and is conceived to be a neurodevelopmental aberration. The possibility that the cavum is a marker of vulnerability to stress in psychopathology is discussed.

Explorations in Virtual Reality: Absorption, Cognition and Altered State of Consciousness

In this exploratory study, we investigated whether Virtual Reality (VR) has the potential to be a research tool for studying consciousness and cognition. We took into consideration both individual differences in absorption (leading to varying degrees of interaction and experience in VR), and the specific cognitive set with which the participant enters the VR (instructions emphasizing either introspective sensitization or metaphoric-symbolic cognition). High absorption was found to predispose subjects to experience an altered state of consciousness. Furthermore, this susceptibility was moderated by the cognitive set employed. Unfortunately, the particular VR game was rather violent, and tended to make our subjects “turn off” the focus on their own subjective experience. We speculate regarding future developments in this domain.