Selective Attention Conditions Research Articles

The Optimal Speech-to-Background Ratio for Balancing Speech Recognition With Environmental Sound Recognition.

This study aimed to determine the speech-to-background ratios (SBRs) at which normal-hearing (NH) and hearing-impaired (HI) listeners can recognize both speech and environmental sounds when the two types of signals are mixed. Also examined were the effect of individual sounds on speech recognition and environmental sound recognition (ESR), and the impact of divided versus selective attention on these tasks. In Experiment 1 (divided attention), 11 NH and 10 HI listeners heard sentences mixed with environmental sounds at various SBRs and performed speech recognition and ESR tasks concurrently in each trial. In Experiment 2 (selective attention), 20 NH listeners performed these tasks in separate trials. Psychometric functions were generated for each task, listener group, and environmental sound. The range over which speech recognition and ESR were both high was determined, as was the optimal SBR for balancing recognition with ESR, defined as the point of intersection between each pair of normalized psychometric functions. The NH listeners achieved greater than 95% accuracy on concurrent speech recognition and ESR over an SBR range of approximately 20 dB or greater. The optimal SBR for maximizing both speech recognition and ESR for NH listeners was approximately +12 dB. For the HI listeners, the range over which 95% performance was observed on both tasks was far smaller (span of 1 dB), with an optimal value of +5 dB. Acoustic analyses indicated that the speech and environmental sound stimuli were similarly audible, regardless of the hearing status of the listener, but that the speech fluctuated more than the environmental sounds. Divided versus selective attention conditions produced differences in performance that were statistically significant yet only modest in magnitude. In all conditions and for both listener groups, recognition was higher for environmental sounds than for speech when presented at equal intensities (i.e., 0 dB SBR), indicating that the environmental sounds were more effective maskers of speech than the converse. Each of the 25 environmental sounds used in this study (with one exception) had a span of SBRs over which speech recognition and ESR were both higher than 95%. These ranges tended to overlap substantially. A range of SBRs exists over which speech and environmental sounds can be simultaneously recognized with high accuracy by NH and HI listeners, but this range is larger for NH listeners. The single optimal SBR for jointly maximizing speech recognition and ESR also differs between NH and HI listeners. The greater masking effectiveness of the environmental sounds relative to the speech may be related to the lower degree of fluctuation present in the environmental sounds as well as possibly task differences between speech recognition and ESR (open versus closed set). The observed differences between the NH and HI results may possibly be related to the HI listeners' smaller fluctuating masker benefit. As noise-reduction systems become increasingly effective, the current results could potentially guide the design of future systems that provide listeners with highly intelligible speech without depriving them of access to important environmental sounds.

Dichotic-listening performance after complete callosotomy: No relief from left-ear extinction by selective attention

The surgical section of the corpus callosum (callosotomy) has been frequently demonstrated to result in a left-ear extinction in dichotic listening. That is, callosotomy patients report the left-ear stimulus below chance level, resulting in substantially enhanced right-ear advantage (REA) compared with controls. A small number of previous studies also suggest that callosotomy patients can overcome left-ear extinction when the instruction encourages to attend selectively to the left-ear stimulus. In the present case study, we re-examine the role of selective attention in dichotic listening in two patients with complete callosotomy and 40 age- and sex-matched controls. We used the standardised Bergen dichotic-listening paradigm which uses stop-consonant-vowel syllables as stimulus material and includes both a free-report and selective-attention condition. As was predicted, both patients showed a clear left-ear extinction. However, contrasting the earlier reports, we did not find any evidence for a relief from this extinction by selectively attending to the left-ear stimulus. We conclude that previous demonstrations of an attention-improved left-ear recall in callosotomy patients may be attributed to the use of suboptimal dichotic paradigms or residual callosal connectivity, rather than representing a genuine effect of attention.

Attention and Memory in Depersonalization-Spectrum Dissociative Disorders: Impact of Selective-Divided Attentional Condition, Stimulus Emotionality, and Stress

ABSTRACT We investigated cognition in depersonalization-spectrum dissociative disorders without comorbid posttraumatic stress disorder to explore evidence for emotionally avoidant information processing. Forty-eight participants with DSM-IV dissociative disorder (DD) (Depersonalization Disorder – 37, Dissociative Disorder NOS −11), 36 participants with Posttraumatic Stress Disorder (PTSD), and 56 healthy controls (HC) were administered the Weschler Adult Intelligence Scale-III (WAIS); the Weschler Memory Scale-III (WMS); and three Stroop tasks: the Standard Stroop, a selective-attention Emotional Stroop using neutral, dissociation, and trauma-related word categories, and a divided-attention Emotional Stroop using comparable words. Participants were also administered a paired-associates explicit and implicit memory test using emotionally neutral and negative words, before and after the Trier Social Stress Test. The DD and HC groups had comparable general intelligence and memory scores, though dissociation severity was inversely related to verbal comprehension and working memory. In the selective-attention condition, DD participants showed greater incidental recall across word categories with comparable interference. However in the divided-attention condition, DD participants significantly favored lesser attentional interference at the expense of remembering words. Across attentional conditions, DD participants had better recall for disorder-related than neutral words. Pre-stress, the DD group demonstrated better explicit memory for neutral versus negative words with reversal after stress, whereas the HC group demonstrated the opposite pattern; implicit memory did not differ. Cognition in the PTSD control group was generally dissimilar to the DD group. The findings in toto provide substantial evidence for emotionally avoidant information processing in DD, vulnerable to the impact of stress, at the level of both attention and memory.

Perception of temporal cues in word segments under bimodal divided attention in simulated cochlear implant listening

Auditory temporal processing is important for cochlear-implant (CI) users to understand speech. Speech processing often unfolds along with sensory inputs from other modalities. This study examined whether dividing attention across modalities affects temporal processing of word segments in simulated CI listening. Adults with normal hearing performed categorization tasks on unprocessed and 8-channel vocoded versions of a Dish-Ditch contrast with varying silent intervals preceding the word-final fricative. The categorization performance was measured concurrently with a visual working memory task on meaningless images. This divided attention (AV-div) condition was compared with an audiovisual selective attention (AV-sel) condition in which participants focused on the categorization task and ignored the visual stimuli, and with an auditory-only (AO) condition in which participants performed the categorization task without the visual stimuli. Preliminary results (N = 5) revealed that participants tended to report more “Dish” responses for words with longer silence intervals under the two AV conditions than the AO condition, especially for the AV-div condition. The AV-related effects on the categorization performance appear to be reduced for vocoded than unprocessed words. These results suggest that concurrent visual information affects auditory temporal processing, which might lead to speech understanding difficulties of CI users in multisensory contexts.

Semantically Congruent Bimodal Presentation with Divided-Modality Attention Accelerates Unisensory Working Memory Retrieval.

Although previous studies have shown that semantic multisensory integration can be differentially modulated by attention focus, it remains unclear whether attentionally mediated multisensory perceptual facilitation could impact further cognitive performance. Using a delayed matching-to-sample paradigm, the present study investigated the effect of semantically congruent bimodal presentation on subsequent unisensory working memory (WM) performance by manipulating attention focus. The results showed that unisensory WM retrieval was faster in the semantically congruent condition than in the incongruent multisensory encoding condition. However, such a result was only found in the divided-modality attention condition. This result indicates that a robust multisensory representation was constructed during semantically congruent multisensory encoding with divided-modality attention; this representation then accelerated unisensory WM performance, especially auditory WM retrieval. Additionally, an overall faster unisensory WM retrieval was observed under the modality-specific selective attention condition compared with the divided-modality condition, indicating that the division of attention to address two modalities demanded more central executive resources to encode and integrate crossmodal information and to maintain a constructed multisensory representation, leaving few resources for WM retrieval. Additionally, the present finding may support the amodal view that WM has an amodal central storage component that is used to maintain modal-based attention-optimized multisensory representations.

Sex hormones modulate sex differences and relate to hemispheric asymmetries in a divided visual field Navon task

Sex differences in functional hemispheric asymmetries (FHA) have been hypothesized as a fundamental mechanism behind sex differences in global-local processing. So far, it has not been assessed how interactive effects of sex and hemifield presentation influence common indicators of global precedence. The current study is the first to investigate the involvement of FHAs by using a divided visual field Navon paradigm and controlling for sex hormone status. Moreover, various factors that have previously shown a reliable influence on global-local processing performance are verified within the context of unilateral presentation. 39 men and 39 naturally cycling women in their luteal cycle phase completed a divided visual field Navon task with the instruction to detect targets either at any level (divided attention) or only at the global or local level (selective attention) in three different spacing conditions. The obtained evidence reveals significant sex differences in the global advantage effect (faster reaction to global vs. local level targets) for densely spaced letter stimuli, as well as significant sex differences in global-local level interference, with findings on both measures being mediated by testosterone. Also, estradiol showed different relationships to the global advantage effect in men and women together with a positive relationship to global advantage for the selective attention condition. Behavioural reaction time results were mirrored by accuracy measures but presented significantly higher global- over local-level accuracy in women compared to men for the divided attention condition. Our results did not show significant sex differences in FHAs but indicate differential relationships between progesterone and FHAs in men and women. In conclusion, sex hormones emerged as central mediators of sex differences in global precedence and possible moderators of hemispheric asymmetries.

Selective and divided attention modulates audiovisual integration in adolescents

In this article, we choose to set up the control group of adults in order to explore whether there are differences in audiovisual integration between divided attention and selective attention in adolescents. We utilized a visual and/or auditory detection task that consisted of three blocks: divided attention, visual selective attention, and auditory selective attention. The results showed that response times were faster for bimodal audiovisual stimuli than for unimodal auditory or visual stimuli in both the divided and selective attention conditions (all p < .05). Then, we found that audiovisual behavioral facilitation effects in the visual selective attention condition were weaker than those in the divided attention condition in adolescents and adults (p < .001). Moreover, an analysis based on race model showed no significant difference between adolescents and adults under divided (t = 1.386, p = .171) or visual selective (t = -1.026, p = .311) attention conditions, which suggests that multisensory integration in adolescents had reached an adult level. These findings indicate that attention can modulate audiovisual integration in adolescents. These results may help researchers to further understand adolescents' cognitive characteristics.

Hearing-Impaired Listeners Show Reduced Attention to High-Frequency Information in the Presence of Low-Frequency Information.

Many listeners with sensorineural hearing loss have uneven hearing sensitivity across frequencies. This study addressed whether this uneven hearing loss leads to a biasing of attention to different frequency regions. Normal-hearing (NH) and hearing-impaired (HI) listeners performed a pattern discrimination task at two distant center frequencies (CFs): 750 and 3500 Hz. The patterns were sequences of pure tones in which each successive tonal element was randomly selected from one of two possible frequencies surrounding a CF. The stimuli were presented at equal sensation levels to ensure equal audibility. In addition, the frequency separation of the tonal elements within a pattern was adjusted for each listener so that equal pattern discrimination performance was obtained for each CF in quiet. After these adjustments, the pattern discrimination task was performed under conditions in which independent patterns were presented at both CFs simultaneously. The listeners were instructed to attend to the low or high CF before the stimulus (assessing selective attention to frequency with instruction) or after the stimulus (divided attention, assessing inherent frequency biases). NH listeners demonstrated approximately equal performance decrements (re: quiet) between the two CFs. HI listeners demonstrated much larger performance decrements at the 3500 Hz CF than at the 750 Hz CF in combined-presentation conditions for both selective and divided attention conditions, indicating a low-frequency attentional bias that is apparently not under subject control. Surprisingly, the magnitude of this frequency bias was not related to the degree of asymmetry in thresholds at the two CFs.

Investigation of the effects of transcranial direct current stimulation and neurofeedback by continuous performance test

Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulation technique based on weak direct current stimulation through the scalp. Neurofeedback (NFB) is a learning strategy that may help alter to brain wave parameters, by monitoring electroencephalography (EEG) feedback via special programs. We aimed to investigate the supportive effects of tDCS in addition to NFB training. 16 healthy volunteers were divided equally into two groups. One of the groups was trained by NFB with the sensorimotor rhythm (SMR) protocol; 2 days per week, 10 sessions of 30 min, the other group received 10 min of tDCS before each NFB sessions. Continuous Performance Test (CPT) was used to measure, response time and suppression and to determine selective attention condition. Also, Beck Depression and Anxiety Inventories were used to exclude people with depression and anxiety. Depression scores of NFB + tDCS group were decreased significantly. CPT scores were better at last sessions for both groups compared to the first sessions. Sessions were analyzed by comparing 1st, 2nd, 5th and 10th sessions. While the NFB + tDCS group had statistically significant changes at theta/beta ratios with SMR and alpha band amplitudes, NFB group statistics had changed at theta/SMR ratios. NFB training shows its effects at the end of 10 sessions. Despite an increase in the latencies of correct and commission responses on the task of CPT, additional use of tDCS improves cognitive performance. Also, tDCS has a supportive effect on the healthy participants who have mild anxiety and depression; also inhibition deficits of subjects were clear.

Bimodal-divided attention attenuates visually induced inhibition of return with audiovisual targets.

Inhibition of return (IOR) refers to the slower response to a target appearing at a previously attended location in a cue-target paradigm. It has been greatly explored in the visual or auditory modality. This study investigates differences between the IOR of audiovisual targets and the IOR of visual targets under conditions of modality-specific selective attention (Experiment 1) and divided-modalities attention (Experiment 2). We employed an exogenous spatial cueing paradigm and manipulated the modalities of targets, including visual, auditory, or audiovisual modalities. The participants were asked to detect targets in visual modality or both visual and auditory modalities, which were presented on the same (cued) or opposite (uncued) side as the preceding visual peripheral cues. In Experiment 1, we found the comparable IOR with visual and audiovisual targets when participants were asked to selectively focus on visual modality. In Experiment 2, however, there was a smaller magnitude of IOR with audiovisual targets as compared with visual targets when paying attention to both visual and auditory modalities. We also observed a reduced multisensory response enhancement effect and race model inequality violation at cued locations relative to uncued locations. These results provide the first evidence of the IOR with audiovisual targets. Furthermore, IOR with audiovisual targets decreases when paying attention to both modalities. The interaction between exogenous spatial attention and audiovisual integration is discussed.

Divided attention effects are larger for change detection than for simple detection

Studies of divided visual attention have largely depended on detection and search tasks because they minimize the role of memory and decision. Recently, the change detection paradigm has been used to study divided attention and the results interpreted as due to perception. Instead, might the divided attention effects in change detection be "inflated" by memory and decision? To consider this, we compare divided attention effects for change detection and simple detection. Subjects were presented two intervals of dynamic 1/f noise patches on the left and right side of fixation and were cued beforehand to attend to either one side (selective attention) or both sides (divided attention). For the change detection task, Gabor patches were embedded in the noise on both sides, in both intervals, with a 50% chance of a 90 degree change in orientation from the first interval to the second. The probability of change was independent across sides. For the simple detection task, Gabor patches appeared in each side with 50% probability and subjects were asked to detect the presence of the patch. For the change detection task, subjects performed worse in the divided attention condition compared to the selective attention condition. However, for the simple detection task, there was almost no cost of divided attention compared to selective attention. In summary, for nearly identical stimuli, we show that the magnitude of divided attention effects depends strongly on the task. Ongoing studies examine whether these task effects depend only on perception or also on memory and/or decision. Meeting abstract presented at VSS 2017

It\u2019s in the eye of the beholder: selective attention to drink properties during tasting influences brain activation in gustatory and reward regions

Statements regarding pleasantness, taste intensity or caloric content on a food label may influence the attention consumers pay to such characteristics during consumption. There is little research on the effects of selective attention on taste perception and associated brain activation in regular drinks. The aim of this study was to investigate the effect of selective attention on hedonics, intensity and caloric content on brain responses during tasting drinks. Using functional MRI brain responses of 27 women were measured while they paid attention to the intensity, pleasantness or caloric content of fruit juice, tomato juice and water. Brain activation during tasting largely overlapped between the three selective attention conditions and was found in the rolandic operculum, insula and overlying frontal operculum, striatum, amygdala, thalamus, anterior cingulate cortex and middle orbitofrontal cortex (OFC). Brain activation was higher during selective attention to taste intensity compared to calories in the right middle OFC and during selective attention to pleasantness compared to intensity in the right putamen, right ACC and bilateral middle insula. Intensity ratings correlated with brain activation during selective attention to taste intensity in the anterior insula and lateral OFC. Our data suggest that not only the anterior insula but also the middle and lateral OFC are involved in evaluating taste intensity. Furthermore, selective attention to pleasantness engaged regions associated with food reward. Overall, our results indicate that selective attention to food properties can alter the activation of gustatory and reward regions. This may underlie effects of food labels on the consumption experience of consumers.

The Influence of Selective and Divided Attention on Audiovisual Integration in Children.

This article aims to investigate whether there is a difference in audiovisual integration in school-aged children (aged 6 to 13 years; mean age = 9.9 years) between the selective attention condition and divided attention condition. We designed a visual and/or auditory detection task that included three blocks (divided attention, visual-selective attention, and auditory-selective attention). The results showed that the response to bimodal audiovisual stimuli was faster than to unimodal auditory or visual stimuli under both divided attention and auditory-selective attention conditions. However, in the visual-selective attention condition, no significant difference was found between the unimodal visual and bimodal audiovisual stimuli in response speed. Moreover, audiovisual behavioral facilitation effects were compared between divided attention and selective attention (auditory or visual attention). In doing so, we found that audiovisual behavioral facilitation was significantly difference between divided attention and selective attention. The results indicated that audiovisual integration was stronger in the divided attention condition than that in the selective attention condition in children. Our findings objectively support the notion that attention can modulate audiovisual integration in school-aged children. Our study might offer a new perspective for identifying children with conditions that are associated with sustained attention deficit, such as attention-deficit hyperactivity disorder.

What makes your brain suggestible? Hypnotizability is associated with differential brain activity during attention outside hypnosis

Theoretical models of hypnosis have emphasized the importance of attentional processes in accounting for hypnotic phenomena but their exact nature and brain substrates remain unresolved. Individuals vary in their susceptibility to hypnosis, a variability often attributed to differences in attentional functioning such as greater ability to filter irrelevant information and inhibit prepotent responses. However, behavioral studies of attentional performance outside the hypnotic state have provided conflicting results. We used fMRI to investigate the recruitment of attentional networks during a modified flanker task in High and Low hypnotizable participants. The task was performed in a normal (no hypnotized) state. While behavioral performance did not reliably differ between groups, components of the fronto-parietal executive network implicated in monitoring (anterior cingulate cortex; ACC), adjustment (lateral prefrontal cortex; latPFC), and implementation of attentional control (intraparietal sulcus; IPS) were differently activated depending on the hypnotizability of the subjects: the right inferior frontal gyrus (rIFG) was more recruited, whereas IPS and ACC were less recruited by High susceptible individuals compared to Low. Our results demonstrate that susceptibility to hypnosis is associated with particular executive control capabilities allowing efficient attentional focusing, and point to specific neural substrates in right prefrontal cortex. Significance statementWe demonstrated that outside hypnosis, low hypnotizable subjects recruited more parietal cortex and anterior cingulate regions during selective attention conditions suggesting a better detection and implementation of conflict. However, outside hypnosis the right inferior frontal gyrus (rIFG) was more recruited by highly hypnotizable subjects during selective attention conditions suggesting a better control of conflict. Furthermore, in highly hypnotizable subjects this region was more connected to the default mode network suggesting a tight dialogue between internally and externally driven processes that may permit higher flexibility in attention and underlie a greater ability to dissociate.

Attentional Sets Influence Perceptual Load Effects, but not Dilution Effects

Perceptual load theory [Lavie, N. (1995). Perceptual load as a necessary condition for selective attention. Journal of Experimental Psychology: Human Perception and Performance, 21, 451-468.; Lavie, N., & Tsal, Y. (1994) Perceptual load as a major determinant of the locus of selection in visual attention. Perception & Psychophysics, 56, 183-197.] proposes that interference from distractors can only be avoided in situations of high perceptual load. This theory has been supported by blocked design manipulations separating low load (when the target appears alone) and high load (when the target is embedded among neutral letters). Tsal and Benoni [(2010a). Diluting the burden of load: Perceptual load effects are simply dilution effects. Journal of Experimental Psychology: Human Perception and Performance, 36, 1645-1656.; Benoni, H., & Tsal, Y. (2010). Where have we gone wrong? Perceptual load does not affect selective attention. Vision Research, 50, 1292-1298.] have recently shown that these manipulations confound perceptual load with "dilution" (the mere presence of additional heterogeneous items in high-load situations). Theeuwes, Kramer, and Belopolsky [(2004). Attentional set interacts with perceptual load in visual search. Psychonomic Bulletin & Review, 11, 697-702.] independently questioned load theory by suggesting that attentional sets might also affect distractor interference. When high load and low load were intermixed, and participants could not prepare for the presentation that followed, both the low-load and high-load trials showed distractor interference. This result may also challenge the dilution account, which proposes a stimulus-driven mechanism. In the current study, we presented subjects with both fixed and mixed blocks, including a mix of dilution trials with low-load trials and with high-load trials. We thus separated the effect of dilution from load and tested the influence of attentional sets on each component. The results revealed that whereas perceptual load effects are influenced by attentional sets, the dilution component is not. This strengthens the notion that dilution is a stimulus-driven mechanism, which enables effective selectivity.

Interhemispheric cooperation in global–local visual processing in pediatric multiple sclerosis

Impairments in visuospatial abilities are commonly reported in children and adolescents with multiple sclerosis (MS). Corpus callosum (CC) pathology occurs in patients with MS and may contribute to impairment in visuospatial perception, particularly when interhemispheric information transfer is required. This study used a global–local hierarchical letter paradigm to examine the relationship between interhemispheric information transfer and white matter integrity in the CC assessed using diffusion tensor imaging. Thirteen cognitively preserved pediatric-onset MS patients and 15 age-matched healthy controls were asked to determine whether a target letter E appeared at the attended level of the stimulus. As expected, both groups processed global and local information more slowly under divided than selective attention conditions. The MS group performed similarly to the control group with respect to reaction time and accuracy on selective and divided attention conditions, with one exception. Specifically, the presence of a global target when attending to a local target caused greater response conflict in the MS group than in controls (p = .01). Pooling both the patient and control data, greater response conflict was associated with reduced white matter integrity as indicated by lower fractional anisotropy in the anterior body of the CC (r = –.33, p < .05). Results suggest that reduced white matter integrity in anterior regions of the CC may lead to less efficient inhibition of task-irrelevant global information in the hierarchal processing of visual information.

Can Musicians Track Two Different Beats Simultaneously?

The simultaneous presence of different meters is not uncommon in Western art music and the music of various non-Western cultures. However, it is unclear how listeners and performers deal with this situation, and whether it is possible to cognitively establish and maintain different beats simultaneously without integrating them into a single metric framework. The present study is an attempt to address this issue empirically. Two rhythms, distinguished by pitch register and representing different meters (2/4 and 6/8), were presented simultaneously in various phase relationships, and participants (who were classically trained musicians) had to judge whether a probe fell on the beat in one or both rhythms. In a selective attention condition, they had to attend to one rhythm and to ignore the other, whereas in a divided attention condition, they had to attend to both. In Experiment 1, participants performed significantly better in the divided attention condition than predicted if they had been able to attend to only one rhythm at a time. In Experiments 2 and 3, however, which used more complex combinations of rhythms, performance did not differ significantly from chance. These results suggest that in Experiment 1 participants relied on the composite beat pattern (i.e., a nonisochronous sequence corresponding to the serial ordering of the two underlying beats) rather than tracking the two beats independently, while in Experiments 2 and 3, the level of complexity of the composite beat pattern may have prevented participants from tracking both beats simultaneously.

The Integration of Stimulus Dimensions in the Perception of Music

A central aim of cognitive psychology is to explain how we integrate stimulus dimensions into a unified percept, but how the dimensions of pitch and time combine in the perception of music remains a largely unresolved issue. The goal of this study was to test the effect of varying the degree of conformity to dimensional structure in pitch and time (specifically, tonality and metre) on goodness ratings and classifications of melodies. The pitches and durations of melodies were either presented in their original order, as a reordered sequence, or replaced with random elements. Musically trained and untrained participants (24 each) rated melodic goodness, attending selectively to the dimensions of pitch, time, or both. Also, 24 trained participants classified whether or not the melodies were tonal, metric, or both. Pitch and temporal manipulations always influenced responses, but participants successfully emphasized either dimension in accordance with instructions. Effects of pitch and time were mostly independent for selective attention conditions, but more interactive when evaluating both dimensions. When interactions occurred, the effect of either dimension increased as the other dimension conformed more to its original structure. Relative main effect sizes (| pitch η(2) - time η(2) |) predicted the strength of pitch-time interactions (pitch × time η(2)); interactions were stronger when main effect sizes were more evenly matched. These results have implications for dimensional integration in several domains. Relative main effect size could serve as an indicator of dimensional salience, such that interactions are more likely when dimensions are equally salient.

Attentional shifts have little effect on the waveform of the chromatic onset VEP

Attention is important for sufficient performance on many visual tasks. This has been shown using achromatic steady-state and pattern-reversal VEPs. Waveform characteristics typically attenuate when attending to distractor stimuli and ignoring VEP stimuli. Chromatic pattern-onset responses have not been tested under conditions of selective attention: as they can be used in clinical settings to test color vision, it is important to know what effects attentional shifts would have on this response. In the present study chromatic pattern-onset VEPs were recorded using spatially divided and spatially contiguous VEP and distractor stimuli. VEP stimuli were 1 cycle.deg(-1) horizontal sine wave patterns (onset mode 100 ms on/400 ms off) used to selectively modulate the L-M and S-(L+M) visual pathways. Distracter stimuli were letters. Subjects attended to either the letters or the gratings and pressed a button when a predetermined stimulus appeared. In Experiment one, VEP and distractor stimuli were superimposed and spatially contiguous. In Experiment two, stimuli were presented to different hemifields. No significant changes in waveform amplitude and latency were found between VEP and distractor attention conditions for either visual pathway. For the chromatic pattern-onset response, modulation of attention does not change responses either with spatially contiguous or spatially separate selective attention manipulations. Consequently, it may not be necessary to monitor attention during recording of this response.

Cognitive performance in older males is associated with growth hormone secretion

Decreases in GH secretion with age may contribute to cognitive changes associated with aging. We evaluated the relation between GH secretion and cognition in elderly males by assessing correlations between GH secretion and performance on cognitive tests in conjunction with recording of event-related potentials (ERPs) to assess underlying neurophysiological mechanisms. GH secretion of 17 elderly male participants was assessed by a GHRH-GHRP-6 test. Standardized neuropsychological tests were used to assess cognitive function. EEG/ERPs were recorded to assess on-line electrocortical correlates of sensory-cortical processing and selective attention. GH secretion was significantly correlated with target detections and speed of responding in the selection-potential task. Furthermore, GH peak was significantly correlated with the performance letter-digit span test. The present data confirm that cognitive performance in elderly males is associated with GH secretion, with respect to target detection and speed of responding in conditions of selective attention, short-term memory, and basic processing speed.