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Manipulation of attention in highly and low hypnotizable individuals: a study on verbal priming
No full textThis study investigated the effects of manipulation of attention on verbal priming in highly (Highs) and low (Lows) hypnotizable individuals. Priming was evaluated via the word-stem completion task (WSCT). The experimental paradigm consisted of one condition in full-attention and in two conditions with colored words in which attention was directed, respectively, only to the color and to both color and word. No significant differences between Highs and Lows were found in none of the three attentional conditions. However, during encoding in full-attention, Highs showed shorter reaction times (RTs) than Lows. This is in accord with previous evidence of faster simple and choice RTs in Highs than in Lows, and suggests hypnotizability-related differences in arousal, likely driven by a different cognitive control activity. Also, Highs' self-report of interference of color-naming on word-reading suggests possible differences between Highs and Lows in cognitive activity related to mental effort
Le origini “aristocratiche” della biennale di venezia. considerazioni sul ruolo degli artisti-organizzatori
No full textIl saggio approfondisce l'esegesi della nascita dell'Esposizione Internazionale Biennale d'Arte di Venezia, attraverso l'analisi dei documenti d'archivio nell'ottica di intendere il peso avuto dagli artisti nella definizione delle caratteristiche dell'esposizione neonata. Ne è emerso un dibattito cocente fra il segretario Antonio Fradeletto, e la componente artistica presente nei vari comitati di consulenza. L'approfondimento è stato occasione anche di confronto con l'ordinamento e l'indirizzo di altre esposizioni internazionali d'oltralpe chiamate in causa dagli stessi artisti che hanno partecipato alla fondazione dell'esposizione apportando contributi e pareri eterogenei messi in accordo da Fradeletto. Si intende così aver contribuito alla comprensione del ruolo delle prime Biennali nello scenario del sistema espositivo internazionale di fine Ottocento
Fear-object perception: does it entail the involuntary capture of attention?
No full textThe idea that fearful stimuli are automatically detected i.e. without attention, is challenged by the hypothesis that detection of threatening stimuli is facilitated by the involuntary, stimulus-driven recruitment of attentional resources. In order to clarify this question, we studied spiders detection in arachnophobic individuals by means of an iconic version of the Attentional Blink Task (AB). The experiment consisted of two tasks: 1) Probe detection within a rapid sequence of distractors, including a Critical Distractor (CD); 2) Probe detection and identification of the CD (Target). In this case, the close temporal proximity of CD-Target and Probe typically produces the so-called AB effect, that is the decrease of Probe visibility, due to competition for limited attentional resources. In both tasks, CD-Target was either a spider (50%) or an innocuous animal shape (50%), and Probe (a rabbit icon) was presented at one out of 3 possible lags from the CD-Target. At lag I (100 ms), arachnophobics, at difference with controls, exhibited an AB effect also when the spider was the CD to be ignored. Moreover, Probe detection scores were inversely correlated with spider recalls at lag I. In conclusion, our findings contrast the automatic view of threat detection, and support an attention capturing mechanism automatically driven by the fearful connotation of the stimulus
Hypnotizability and spatial attentional functions
No full textMany theories of hypnotic responding have proposed that differences in hypnotic trait rely on differences in frontal attentional functions. Evidence of hypnotizability-related attentional abilities are, however, very scant. This study was designed to investigate the relationship between hypnotizability and executive control components of attention in the spatial domain. We chose the Attention Network Test that enables to analyze alerting, orienting and executive control functions by measuring reaction times (RTs) to targets cued for different locations in space. According to Posner theory, alerting, orienting and executive control effects were found in both groups. No differences between highly susceptible (Highs) and low susceptible individuals (Lows) on executive control functions were found. However, in Highs alerting was significantly smaller than in Lows and Highs were significantly faster than Lows in the no and central cue conditions. These findings suggest that Highs would be endowed with a basal higher efficiency in achieving and maintaining their readiness to respond to incoming stimuli. This relation between hypnotizability and alerting, is discussed in terms of a possible more efficient noradrenergic activity driven by frontal attentional systems
Hypnotizabilityand temporal dynamics of attention: a study on the Attentional Blink effect
No full textThis study was designed to seek hypnotizability-related differences in attention temporal dynamics. For this purpose, an iconic version of the Attentional Blink Task (AB) was performed on 18 highly (Highs, score 9-12, SHSS form C) and 18 low susceptible individuals (Lows, score 0-3). The procedure consisted of two tasks in which two animal shapes (a coloured animal, Target, and a black butterfl y, Probe) appeared in close temporal proximity within a rapid stream of distractors (black animals). In the Single task only Probe detection was required; in the Conditional task, Target identifi cation was also requested. In this case, competition between Target and Probe for limited attentional resources decreases Probe visibility as a function of the time lag from Target (AB effect). A similar AB effect occurred in the two groups; nonetheless, Probe detection scores at the shorter lags were frequently higher in Highs than in Lows. This suggests that time constraints could affect the performance of Highs less than Lows, but also that the two groups could differ in attention capturing mechanisms, i.e. automatic capture by colour at the shorter lag. Moreover, Highs scores on Target identifi cation were lower than Lows' ones indicating an impairment of Highs when engaged in dual tasks
Emotion processing without awareness: features detection or significance evaluation?
No full textStudies on the physiological responses to emotional stimuli demonstrated that they can occur even when emotional stimuli are not consciously perceived. In this study, the subliminal stimulation was obtained by means of Backward Masking. Specifically, we analyzed the cardiac and electrodermal responses evoked by the unmasked and masked presentation of spider shapes in arachnophobic individuals. To evaluate whether unaware processing entails discrimination of physical features vs emotional significance, crabs, morphologically similar to the spiders but different for emotional significance, and squirrels, different in both shape and emotional content, were also employed. The response to unmasked spiders consisted of a typical defense response (sympathetic activation), while that to innocuous stimuli of an orienting response (moderate electrodermal and vagal activations). In the subliminal condition, the electrodermal response to masked spiders was greater than that to the other animals suggesting an early detection of emotional content rather than of physical characteristics. In contrast, cardiac responses to the masked stimuli did not show any differences as a function of valence. These findings suggest that individuals can appraise the emotional content of unconsciously perceived stimuli and react with an arousal response. However, subliminal emotional stimuli does not seem able to elicit the complete pattern of autonomic responses typical of the defense response
Hypnotic assessment based on the Recurrence Quantification Analysis of EEG recorded in the ordinary state of consciousness
No full textThe cerebral cortical correlates of the susceptibility to hypnosis in the ordinary states of consciousness have not been clarified. Aim of the study was to characterize the EEG dynamics of subjects with high (highs) and low hypnotisability (lows) through the non-linear method of Recurrence Quantification Analysis (RQA). The EEG of 16 males - 8 highs and 8 lows - was monitored for 1 min without instructions other than keeping the eyes closed, being silent and avoiding movements (short resting), and during 15 min of simple relaxation, that is with the instruction to relax at their best. Highs and lows were compared on the RQA measures of Determinism (DET) and Entropy (ENT), which are related to the signal determinism and complexity. In the short resting condition discriminant analysis could classify highs and lows on the basis of DET and ENT values at temporo-parietal sites. Many differences in DET and all differences in ENT disappeared during simple relaxation, although DET still separated the two groups in the earliest 6 min of relaxation at temporo-parietal sites. Our RQA based approach allows to develop computer-based methods of hypnotic assessment using short-lasting, single channel EEG recordings analyzed through standard mathematical methods. (C) 2013 Elsevier Inc. All rights reserved
Inefficient stimulus processing at encoding affects formation of high-order general representation: A study on cross-modal word-stem completion task
Full text linkPriming is an implicit memory effect in which previous exposure to one stimulus influences the response to another stimulus. The main characteristic of priming is that it occurs without awareness. Priming takes place also when the physical attributes of previously studied and test stimuli do not match; in fact, it greatly refers to a general stimulus representation activated at encoding independently of the sensory modality engaged. Our aim was to evaluate whether, in a cross-modal word-stem completion task, negative priming scores could depend on inefficient word processing at study and therefore on an altered stimulus representation. Words were presented in the auditory modality, and word-stems to be completed in the visual modality. At study, we recorded auditory ERPs, and compared the P300 (attention/memory) and N400 (meaning processing) of individuals with positive and negative priming. Besides classical averaging-based ERPs analysis, we used an ICA-based method (ErpICASSO) to separate the potentials related to different processes contributing to ERPs. Classical analysis yielded significant difference between the two waves across the whole scalp. ErpICASSO allowed separating the novelty-related P3a and the top-down control-related P3b sub-components of P300. Specifically, in the component C3, the positive deflection identifiable as P3b, was significantly greater in the positive than in the negative priming group, while the late negative deflection corresponding to the parietal N400, was reduced in the positive priming group. In conclusion, inadequacy of specific processes at encoding, such as attention and/or meaning retrieval, could generate weak semantic representations, making words less accessible in subsequent implicit retrieval
Be(a)ware of spider! An Attentional Blink study on fear detection
No full textWe investigated whether detection of fearful stimuli is independent from attention by using an iconic version of the Attentional Blink Task in arachnophobic individuals. A colored animal icon (Target) and a black spider or butterfly icon (Probe) appeared in close temporal proximity within a stream of distractors, at one of 4 possible time lags. In one task, Probe detection was required; in another one, Target identification was also requested. In this case, competition for attentional resources produces the so-called AB effect, that is the decrease of Probe perception as a function of lag. During spider-Probe detection, arachnophobics showed a reduced AB effect with respect to the butterfly-Probe session. Their spider detection scores were also greater than ratings obtained by non-phobic controls with both Probe types. Thus, fear appears to enhance the probability of consciously perceiving the stimulus even when attention is engaged by a previous demanding event. One may assume that spider-Probe is scarcely attention demanding because detection of threat in arachnophobics is increased by rapid amygdala activation of visual areas and/or facilitated by a strong arousal-induced noradrenergic cortical input. Alternatively, an attention capturing mechanism involuntary triggered by the phobic meaning of the stimulus could be hypothesized
Pain perception and EEG dynamics: Does hypnotizability account for the efficacy of the suggestions of analgesia?
No full textWe report novel findings concerning the role of hypnotizability, suggestions of analgesia and the activity of the Behavioral Inhibition/Activation System (BIS/BAS) in the modulation of the subjective experience of pain and of the associated EEG dynamics. The EEG of high (. highs) and low hypnotizable participants (. lows) who completed the BIS/BAS questionnaire was recorded during basal conditions, tonic nociceptive stimulation without (PAIN) and with suggestions for analgesia (AN). Participants scored the perceived pain intensity at the end of PAIN and AN. The EEG midline dynamics was characterized by indices indicating the signal predictability (Determinism) and complexity (Entropy) obtained through the Recurrence Quantification Analysis. The reduced pain intensity reported by highs during AN was partially accounted for by the activity of the Behavioral Activation System. The decreased midline cortical Determinism observed during nociceptive stimulation in both groups independently of suggestions remained significantly reduced only in lows after controlling for the activity of the Behavioral Activation System. Finally, controlling for the activity of the Behavioral Inhibition System abolished stimulation, suggestions and hypnotizability-related differences. Results indicate that the BIS/BAS activity may be more important than hypnotizability itself in pain modulation and in the associated EEG dynamics
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