Hypnotic suggestion modulates visual recognition of negative words depending on word arousal.

This study examined whether and how emotional hypnotic suggestions modulate the visual recognition of negative words. We investigated the influence of hypnotic suggestions aimed at modifying emotional reactivity on the arousal effect in negative words. High and low suggestible individuals performed a go/no-go lexical decision task in three intra-individual conditions: with a suggestion to increase emotional reactivity, with a suggestion to decrease emotional reactivity and without hypnotic suggestion. Results showed that hypnotic suggestions modulated the arousal facilitation effect differently depending on the level of suggestibility of the participants. In high suggestible individuals, response times for low-arousal negative words varied oppositely according to the suggestion administered, while no modulations were retrieved for high-arousal ones. In contrast, no suggestion effects were found for low suggestible participants. Altogether, these findings suggest a higher influence of hypnotic suggestions on emotional words that require longer processing times in high suggestible individuals.

Modulation of attentional bias by hypnotic suggestion: experimental evidence from an emotional Stroop task.

Hypnosis is considered a unique tool capable of modulating cognitive processes. The extent to which hypnotic suggestions intervenes is still under debate. This study was designed to provide a new insight into this issue, by focusing on an unintentional emotional process: attentional bias. In Experiment 1, highly suggestible participants performed three sessions of an emotional Stroop task where hypnotic suggestions aiming to increase and decrease emotional reactivity towards emotional stimuli were administered within an intra-individual design. Compared to a baseline condition (without hypnotic suggestion), a significant increase in attentional bias was found when a hypnotic suggestion to increase emotional reactivity was administered. In contrast, the bias was eliminated when a suggestion to decrease emotional reactivity was administered. Experiment 2 investigated the effect of session repetition on attentional bias across three successive experimental sessions without hypnosis, and showed that the emotional Stroop effect did not vary across sessions. Hence, session repetition could not account for part of the modulation of attentional bias in Experiment 1. Taken together, the results suggest that specific hypnotic suggestions can influence elicitation of unintentional emotional processing. The implications are discussed regarding the locus of intervention of hypnotic suggestion in cognitive and emotional processes.

Does a yellow filter improve visual object categorization in normal aging?

Previous studies have shown that a yellow filter (CPF450) can increase contrast, motion sensitivity, vergence, and accommodation. We investigated whether a yellow filter can reduce age-related visual deficits. We tested two groups of 60 observers (mean age 24 vs. 72) in an object categorization task. Grayscale photographs of natural objects and artifacts were displayed either centrally or peripherally (21°) at low (8%) or medium (30%) contrast. There were three filter conditions (no filter, placebo filter, and yellow filter). Both groups of observers performed similarly on central and medium-contrast pictures. The deleterious effects of reduced contrast and eccentricity were stronger in elderly individuals. Moreover, the yellow filter globally improved the speed of categorization for the elderly participants. The decrease in response time in the yellow filter condition was larger when the stimuli were displayed peripherally in both groups. A yellow filter should be considered as a potential means for visual improvement in normal aging.

Influence of visual deficits on object categorization in normal aging.

UNLABELLED: BACKGROUND/STUDY CONTEXT: The authors assessed whether age-related changes in low-level vision affects higher-level processes involved in object categorization. METHODS: Thirty young and 30 older observers were asked to categorize gray levels photographs of natural and artifactual objects. The authors manipulated contrast (8% vs. 30%) and eccentricity (central vs. 21° peripheral presentations). RESULTS: Older people were slower and less accurate than young people but this impairment varied with contrast and eccentricity. The pattern of performance was equivalent for young and for old people when pictures were presented centrally with a 30% contrast. Performance was impaired for older people when pictures were presented peripherally with a low contrast. Moreover, a category-specific deficit was found in the old group, specifically for peripheral presentations. DISCUSSION: The results are consistent with an age-related deficit in the ability to categorize objects but the deficit was specifically observed under low-contrast condition and peripheral vision, suggesting a reduced response in the magnocellular pathway. The results are interpreted in the framework of age-related deficits in the two main visual streams.

[Aging of visual object recognition: interaction between a "spatial frequency-specific" deficit and a "category-specific" deficit]. / Vieillissement de la catégorisation visuelle d'objet : interaction entre un déficit « fréquence spatiale-spécifique ¼ et un déficit « catégorie-spécifique ¼

The study investigated the aging of object categorization manipulating the spatial frequency (SF) content in photographs of object and the object category. Thirty young (m=22 years old) and 24 mature adults (m=57 years old) categorized 120 items (animals/tools) presented for 200 ms each, in one of three versions: a normal version (no filter), a band-pass filtered version (medium to high SF) and a low-pass filtered version (low SF). Results showed that this categorization task relied mainly on the medium to high SF band and that the mature group had a large impairment on that band. This impairment resulted for this group in a category-specific deficit toward the tools, for which the weak intra-category similarity in the items requires that SF range to be processed. An impairment of performance with increasing age was also found for the low SF band, specifically for animals. This interaction between the SF-specific deficit with age and the category is discussed according to the relevance of SF band for the task and to the characteristics of the two categories.

Alteration of attentional blink in high functioning autism: a pilot study.

Autism is characterized by deficits in attention. However, no study has investigated the dynamics of attentional processes in autistic patients yet. The attentional blink (AB) paradigm provides information about the temporal dynamics of attention in particular about the allocation and the duration of an attentional episode. We compared 11 high functioning autistic patients with 15 control participants on a classical AB task. Autistic patients exhibited a deficit in rapidly allocated attentional resources. Further investigations such as coupling AB evaluation with neuroimaging data and/or increasing the size of groups, would allow for investigating the neurobiological substrates of these AB alterations in autistic patients.

Psychophysical assessment of magno- and parvocellular function in schizophrenia.

Recently developed psychophysical techniques permit the biasing of the processing of the stimulus by early visual channels so that responses reflect characteristics of either magno- or parvocellular pathways (Pokorny & Smith, 1997). We used such techniques to test psychophysically whether the global magnocellular dysfunction reported in schizophrenia also affects early processes. Seven schizophrenic patients and 19 normal controls participated. The task was a four-alternative forced-choice luminance discrimination, using a 2 x 2 configuration of four 1-deg squares. Target luminance threshold was determined in three conditions: the stimulus, including the target, was pulsed for 17 ms (pulse paradigm); the target was presented on a steady background of four squares (steady paradigm), or the target was presented alone (no background paradigm). We replicated previous results demonstrating magnocellular and parvocellular signatures in control participants. No evidence for an early magnocellular deficit could be detected as the thresholds of all schizophrenic observers were higher both in the steady paradigm (presumed magnocellular mediation) and in the pulse paradigm (presumed parvocellular mediation). Magnocellular dysfunction, if present in schizophrenia, must concern more integrated processes, possibly at levels at which parvocellular and magnocellular paths interact.

The effects of coffee and napping on nighttime highway driving: a randomized trial.

BACKGROUND: Sleep-related accidents often involve healthy young persons who are driving at night. Coffee and napping restore alertness, but no study has compared their effects on real nighttime driving performances. OBJECTIVE: To test the effects of 125 mL of coffee (half a cup) containing 200 mg of caffeine, placebo (decaffeinated coffee containing 15 mg of caffeine), or a 30-minute nap (at 1:00 a.m.) in a car on nighttime driving performance. DESIGN: Double-blind, randomized, crossover study. SETTING: Sleep laboratory and open highway. PARTICIPANTS: 12 young men (mean age, 21.3 years [SD, 1.8]). MEASUREMENTS: Self-rated fatigue and sleepiness, inappropriate line crossings from video recordings during highway driving, and polysomnographic recordings during the nap and subsequent sleep. INTERVENTION: Participants drove 200 km (125 miles) between 6:00 p.m. and 7:30 p.m. (daytime reference condition) or between 2:00 a.m. and 3:30 a.m. (coffee, decaffeinated coffee, or nap condition). After intervention, participants returned to the laboratory to sleep. RESULTS: Nighttime driving performance was similar to daytime performance (0 to 1 line crossing) for 75% of participants after coffee (0 or 1 line crossing), for 66% after the nap (P = 0.66 vs. coffee), and for only 13% after placebo (P = 0.041 vs. nap; P = 0.014 vs. coffee). The incidence rate ratios for having a line crossing after placebo were 3.7 (95% CI, 1.2 to 11.0; P = 0.001) compared with coffee and 2.9 (CI, 1.7 to 5.1; P = 0.021) compared with nap. A statistically significant interindividual variability was observed in response to sleep deprivation and countermeasures. Sleep latencies and efficiency during sleep after nighttime driving were similar in the 3 conditions. LIMITATIONS: Only 1 dose of coffee and 1 nap duration were tested. Effects may differ in other patient or age groups. CONCLUSIONS: Drinking coffee or napping at night statistically significantly reduces driving impairment without altering subsequent sleep.