photic stimulation

The relationship of task relevance and stimulus probability to P300 morphology, latency and distribution was assessed. Eight year olds and adults completed visual oddball tasks of recognition memory with frequent non-target (60%), infrequent target (20%), and infrequent novel (20%) stimuli. Stimuli consisted of 2 female faces posing neutral expressions, and 40 trial unique novel photographs depicting scenes, animals, objects or abstract patterns. Event-related potentials were recorded from 17 electrodes over frontal, central and parietal scalp, including lateral temporal sites. All stimuli elicited P300 responses at parietal electrodes, with the largest responses to the target stimuli (relevant and infrequent). The P300 responses of adults and children were morphologically dissimilar, with children showing broader peaks and latency shifts across electrodes. In addition, the eight year olds displayed a frontal negativity to novel stimuli which was absent in the responses of adult par...

Three experiments investigated whether it is possible to orient selective spatial attention to internal representations held in working memory in a similar fashion to orienting to perceptual stimuli. In the first experiment, subjects were either cued to orient to a spatial location before a stimulus array was presented (pre-cue), cued to orient to a spatial location in working memory after the array was presented (retro-cue), or given no cueing information (neutral cue). The stimulus array consisted of four differently colored crosses, one in each quadrant. At the end of a trial, a colored cross (probe) was presented centrally, and subjects responded according to whether it had occurred in the array. There were equivalent patterns of behavioral costs and benefits of cueing for both pre-cues and retro-cues. A follow-up experiment used a peripheral probe stimulus requiring a decision about whether its color matched that of the item presented at the same location in the array. Replicat...

The role of configural information in gender categorisation was studied by aligning the top half of one face with the bottom half of another. The two faces had the same or different genders. Experiment l shows that participants were slower and made more errors in categorising the gender in either half of these composite faces when the two faces had a different gender, relative to control conditions where the two faces were nonaligned or had the same gender. This result parallels the composite effect for face recognition (Young et al, 1987 Perception16 747–759) and facial-expression recognition (Calder et al, 2000 Journal of Experimental Psychology: Human Perception and Performance26 527–551). Similarly to responses to face identity and expression, the composite effect on gender discrimination was disrupted by inverting the faces (experiment 2). Both experiments also show that the composite paradigm is sensitive to general contextual interference in gender categorisation.

SUMMARY Male glow-worms Lampyris noctiluca find their bioluminescent mates at night by phototaxis. There is good evidence that location of mates by lampyrid beetles is achieved by a single spectral class of photoreceptor,whose spectral sensitivity is tuned to the bioluminescent spectrum emitted by conspecifics, and is achromatic. We ask whether glow-worm phototaxis involves interactions between two spectral classes of photoreceptor. Binary choice experiments were conducted in which males were presented with artificial light stimuli that differ in spectral composition. The normal preference for a green stimulus (λmax=555 nm), corresponding to the bioluminescence wavelength produced by signalling females, was significantly reduced by adding a blue (λmax=485 nm) component to the signal. This implies an antagonistic interaction between long- and short-wavelength sensitive photoreceptors, suggesting colour vision based on chromatic opponency. Cryosections showed a band of yellow filter p...

False working memories readily emerge using a visual item-recognition variant of the converging associates task. Two experiments, manipulating study and test modality, extended prior working memory results by demonstrating a reliable false recognition effect (more false alarms to associatively related lures than to unrelated lures) within seconds of encoding in either the visual or auditory modality. However, false memories were nearly twice as frequent when study lists were seen than when they were heard, regardless of test modality, although study-test modality mismatch was generally disadvantageous (consistent with encoding specificity). A final experiment that varied study-test modality using a hybrid short- and long-term memory test (Flegal, Atkins & Reuter-Lorenz, 2010) replicated the auditory advantage in the short term but revealed a reversal in the long term: The false memory effect was greater in the auditory study-test condition than in the visual study-test condition. Th...

In concatenative languages such as English, the morphemes of a word are linked linearly so that words formed from the same base morpheme also resemble each other along orthographic dimensions. In Hebrew, by contrast, the morphemes of a word can be but are not generally concatenated. Instead, a pattern of vowels is infixed between the consonants of the root morpheme.

Fibromyalgia syndrome (FMS) is characterized by widespread chronic pain, fatigue, sleep disorders, and cognitive-emotional disturbance. Patients with FMS exhibit increased sensitivity to experimental pain and pain-related cues, as well as deficits in emotional regulation. The present study investigated the spatiotemporal patterns of brain activations for observed pain in 19 patients with FMS and 18 age-matched, healthy control individuals using event-related potential analysis. Patients with FMS attributed greater pain and unpleasantness to pain pictures relative to healthy control participants. An augmented late positive potential (LPP) component (>500 milliseconds) was found in patients viewing both pain and nonpain pictures, and this amplitude difference in the LPP covaried with perceived unpleasantness of pictures. Mid-latency potentials (250-450 milliseconds) demonstrated similar amplitude increases of positive potentials in the FMS patient group. By contrast, the short-late...

Recent studies have shown that (1) the global precedence effects in processing the hierarchically organized stimulus can be attenuated by eliminating the low spatial frequencies contained in the stimulus and (2) the human magnocellular pathway is responsible for processing low spatial frequencies and the pathway can be attenuated by imposing a red background on the stimulus. In the present study, a reaction-time experiment was conducted to examine the effect of background color of the stimulus to the processing of the hierarchically organized stimulus. The result showed that although the control condition (a green background) produced a prototypical asymmetric global interference, a red background that was equiluminant to the green background produced a symmetrical interference. It was concluded that the human magnocellular pathway is at least partially responsible in producing the global precedence effects.

The goal of the current study was to evaluate presetting, response inhibition, set shifting, and a priori planning in autism: abilities that can be lumped together under the term cognitive flexibility. Cognitive flexibility is an aspect of executive functioning, which in turn is mediated by the prefrontal cortical lobes. A group of adults with high-functioning autism (HFA; n = 23) were compared with a normal control group (n = 32), by using a computerized variant of the Sternberg response bias paradigm. Contrary to the results of earlier studies, no deficit was found in presetting, response inhibition, set shifting, and a priori planning in participants with autism, even when the medication factor was taken into account. Methodological issues that could be explanatory for this difference are discussed. An additional finding was, that individuals with HFA (especially those on medication) were slow in reacting. Possible origins and consequences of this slowness, also for cognitive flexibility, are discussed.

Flash cards have been shown to be useful for teaching sight-word reading. To date, the most effective flash-card instruction method is incremental rehearsal (IR). This method involves the instructor interspersing unknown stimulus items into the presentation of known stimulus items. In this study, we compared IR to a modified IR procedure—strategic incremental rehearsal (SIR)—to determine whether the effects of IR might be improved by incorporating variables likely to increase word acquisition. These included increased opportunities to respond to unknown stimuli, using learner responding as a basis for changing instructional items, and systematic prompting methods. An A-B-A-B design was used to compare the effects of IR and SIR for increasing sight-word reading with 4 elementary school students. Results indicated that students read more words correctly with SIR than with IR. In addition, similar patterns of responding were seen at a 2-week follow-up.

We investigated how does the structure of empty time intervals influence temporal processing. In experiment 1, the intervals to be discriminated were the silent durations marked by two sensory signals, both lasting 10 or 500 ms; these signals were two identical flashes (intramodal: VV), or one visual flash (V) followed by an auditory tone (A) (intermodal: VA). For the range of duration under investigation (standards = 0.2, 0.6, 1, or 1.4 s), the results indicated that both the marker length and sensory mode influenced discrimination, but no interaction between these variables or between one of these variables and standard duration was significant. In experiment 2, we compared, for each of four marker-type conditions (VV, AA, VA, AV; and standard = 1 s), intervals marked by two 10 ms signals with intervals marked by unequal signal length (markers 1 and 2 lasting 10 and 500 ms, or 500 and 10 ms). As in experiment 1, the results revealed significant marker-mode and marker-length effects, but no significant interaction between these variables. Experiment 3 showed that, for the same conditions as in experiment 2, perceived duration is not influenced by marker length and that the variability of interval reproductions does not depend on the perceived duration of intervals. The results are discussed in the light of a single-clock hypothesis: marker-length and marker-mode effects are presented as being non-temporal sources of variability associated mainly with sensory and memory processes.

The aim of the present paper is to show how the variation of the EEG frontal cortical asymmetry is related to the general appreciation perceived during the observation of TV advertisements, in particular considering the influence of the gender and age on it. In particular, we investigated the influence of the gender on the perception of a car advertisement (Experiment1) and the influence of the factor age on a chewing gum commercial (Experiment2). Experiment1results showed statistically significant higher approach values for the men group throughout the commercial. Results from Experiment2showed significant lower values by older adults for the spot, containing scenes not very enjoyed by them. In both studies, there was no statistical significant difference in the scene relative to the product offering between the experimental populations, suggesting the absence in our study of a bias towards the specific product in the evaluated populations. These evidences state the importance of t...

Combining signals across the senses improves precision and speed of perception, although this multisensory benefit declines for asynchronous signals. Multisensory events may produce synchronized stimuli at source but asynchronies inevitably arise due to distance, intensity, attention and neural latencies. Temporal recalibration is an adaptive phenomenon that serves to perceptually realign physically asynchronous signals. Recently, it was discovered that temporal recalibration occurs far more rapidly than previously thought and does not require minutes of adaptation. Using a classical audiovisual simultaneity task and a series of brief flashes and tones varying in onset asynchrony, perceived simultaneity on a given trial was found to shift in the direction of the preceding trial's asynchrony. Here we examine whether this inter-trial recalibration reflects the same process as prolonged adaptation by combining both paradigms: participants adapted to a fixed temporal lag for several...

Visual motion is sensed by low-level (energy-based) and high-level (feature-based) mechanisms. Ocular following responses (OFR) were elicited in humans by applying horizontal motion to vertical square-wave gratings lacking the fundamental ("missing fundamental stimulus"). Motion consisted of successive 1/4-wavelength steps, so the features and 4n+1 harmonics (where n=integer) shifted forwards, whereas the 4n-1 harmonics--including the strongest Fourier component (the 3rd harmonic)--shifted backwards (spatial aliasing). Initial OFR, recorded with the electromagnetic search coil technique, were always in the direction of the 3rd harmonic, e.g., leftward steps resulted in rightward OFR. Thus, the earliest OFR were strongly dependent on the motion of the major Fourier component, consistent with early spatio-temporal filtering prior to motion detection, as in the well-known energy model of motion analysis.

1 Dep. Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, São Paulo, Brasil 2 Núcleo de Neurociências e Comportamento, Universidade de São Paulo, São Paulo, Brasil 3 Dep. Fisiologia Universidade Federal do Pará, Belém, Brasil 4 Núcleo de ...

There is abundant evidence in memory research that emotional stimuli are better remembered than neutral stimuli. However, effects of an emotionally charged context on memory for associated neutral elements is also important, particularly in trauma and stress-related disorders, where strong memories are often activated by neutral cues due to their emotional associations. In the present study, we used event-related potentials (ERPs) to investigate long-term recognition memory (1-week delay) for neutral objects that had been paired with emotionally arousing or neutral scenes during encoding. Context effects were clearly evident in the ERPs: An early frontal ERP old/new difference (300-500 ms) was enhanced for objects encoded in unpleasant compared to pleasant and neutral contexts; and a late central-parietal old/new difference (400-700 ms) was observed for objects paired with both pleasant and unpleasant contexts but not for items paired with neutral backgrounds. Interestingly, objects...