Olfactory and/or visual cues for spatial navigation through ontogeny: Olfactory cues enable the use of visual cues.

This study analyzed the spatial memory capacities of rats in darkness with visual and/or olfactory cues through ontogeny. Tests were conducted with the homing board, where rats had to find the correct escape hole. Four age groups (24 days, 48 days, 3-6 months, and 12 months) were trained in 3 conditions: (a) 3 identical light cues; (b) 5 different olfactory cues; and (c) both types of cues, followed by removal of the olfactory cues. Results indicate that immature rats first take into account olfactory information but are unable to orient with only the help of discrete visual cues. Olfaction enables the use of visual information by 48-day-old rats. Visual information predominantly supports spatial cognition in adult and 12-month-old rats. Results point out cooperation between vision and olfaction for place navigation during ontogeny in rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dopamine agonists reorient visual exploration away from the neglected hemispace

OBJECTIVE: To study the effects of bromocriptine, a dopamine agonist, on visual search. BACKGROUND: The anatomic substrate of spatial attention takes the form of a distributed network with interconnected cortical (frontal, parietal, and cingulate) and subcortical (striatal and thalamic) components. Dopamine appears to exert a modulatory effect on the function of this network. METHODS: Seven consecutive right-handed subjects with right-sided cerebral lesions were studied using a computerized target search paradigm. Eye movements were recorded. RESULTS: Bromocriptine caused the subjects to spend more time exploring the ipsilesional hemispace and therefore increased the relative neglect of the contralesional left hemispace. However, target detection accuracy did not change. Bromocriptine thus had a differential impact on the exploratory-motor versus sensory-perceptual components of directed attention. CONCLUSIONS: Our results show that bromocriptine may worsen some aspects of hemispatial neglect in patients with lesions that include the postsynaptic components of ascending dopaminergic pathways.     

Detecting anxiety and defensiveness from visual and auditory cues

Defensive individuals have been shown to differ from nondefensive individuals on a number of physiological and behavioral measures. We report two studies on observers' inferences of defensiveness, and the contribution of communication channels in the inference of defensiveness. Observers judged high and low state anxious segments of high and low trait anxious defensive and nondefensive individuals. Accurate assessments were made of (a) defensiveness, (b) state anxiety, and (c) trait anxiety: Individuals with higher levels of each variable were perceived as more anxious compared with the lower level. Effects for defensiveness and state anxiety were greater in audio-only segments, while effects for trait anxiety were greater in video-only segments. Inferences of defensiveness were greater at higher levels of state anxiety and trait anxiety. Low trait anxious defensive individuals were perceived as more anxious than the true low trait anxious. Results for defensiveness and trait anxiety were replicated in Study 2, and observers' perceptions of state anxiety matched individuals' self-reports: Defensive individuals with maximal differences between high and low state anxiety were seen as more anxious in high state anxiety, while defensive individuals with minimal differences between high and low state anxiety were regarded as less anxious in high state anxiety.     

When visual marking meets the attentional blink: More evidence for top-down, limited-capacity inhibition.

An attentional blink (AB) paradigm was used to investigate the attentional resources necessary for visual marking. The results showed that distractors presented inside the AB cannot easily be ignored despite participants anticipating a future target display. This supports the hypothesis that attentional resources are required for visual marking. In addition, probe dots were better detected on blinked distractors than on successfully ignored distractors, but only when the task required new items to be prioritized. In a final experiment, a stronger negative carry-over effect on search occurred for targets identical to distractors presented outside rather than inside the AB. This suggests that at least part of the inhibitory processes involved in visual marking are nonspatial. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is visual imagery really visual? Overlooked evidence from neuropsychology.

Does visual imagery engage some of the same representations used in visual perception? The evidence collected by cognitive psychologists in support of this claim has been challenged by three types of alternative explanation: Tacit knowledge, according to which subjects use nonvisual representations to simulate the use of visual representations during imagery tasks, guided by their tacit knowledge of their visual systems; experimenter expectancy, according to which the data implicating shared representations for imagery and perception is an artifact of experimenter expectancies; and nonvisual spatial representation, according to which imagery representations are partially similar to visual representations in the way they code spatial relations but are not visual representations. This article reviews previously overlooked neuropsychological evidence on the relation between imagery and perception, and discusses its relative immunity to the foregoing alternative explanations. This evidence includes electrophysiological and cerebral blood flow studies localizing brain activity during imagery to cortical visual areas, and parallels between the selective effects of brain damage on visual perception and imagery. Because these findings cannot be accounted for in the same way as traditional cognitive data using the alternative explanations listed earlier, they can play a decisive role in answering the title question. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of gravitational cues on visual search for orientation.

To determine whether nonvisual (vestibular and somatosensory) information participates in low-level orientation processing, Ss in different postural conditions (upright, supine, and sitting immobilized) searched for a target distinguishable from distractors by differences in orientation (A. Treisman's [1985] "pop-out" paradigm). Searches for vertical and horizontal targets were dramatically modified as a function of the postural position, indicating that the processing of orientation in early vision is not only retinal but integrates information from the sensory graviceptors. This visuovestibular phenomenon is interpreted in the conceptual framework of D. H. Foster and P. A. Ward's (1991) model based on local orthogonal orientation filters and T. A. Stoffregen and G. E. Riccio's (1988) dynamics of balance theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Directional asymmetries in interhemispheric transmission time: evidence from visual evoked potentials

The hypothesis was tested that interhemispheric transfer time (IHTT), as measured in the latency of bilaterally recorded visual evoked potentials, is directionally asymmetric, i.e. that an IHTT is faster for transmission from right-to-left hemisphere, than from left-to-right. A meta-analysis of 18 experiments within the published literature reporting visual evoked potential IHTTs indicates a significant experiment-wise predominance of faster right-to-left IHTTs. A new experiment is also reported in which significantly faster right-to-left IHTT was found in visual evoked potentials recorded from parietal electrodes to lateral visual field presentations while subjects performed a task requiring complex stimulus recognition and analysis, and a choice response.     

Benefit from visual cues in auditory-visual speech recognition by middle-aged and elderly persons

The benefit derived from visual cues in auditory-visual speech recognition and patterns of auditory and visual consonant confusions were compared for 20 middle-aged and 20 elderly men who were moderately to severely hearing impaired. Consonant-vowel nonsense syllables and CID sentences were presented to the subjects under auditory-only, visual-only, and auditory-visual test conditions. Benefit was defined as the difference between the scores in the auditory-only and auditory-visual conditions. The results revealed that the middle-aged and elderly subjects obtained similar benefit from visual cues in auditory-visual speech recognition. Further, patterns of consonant confusions were similar for the two groups.     

Contextual cues and release from proactive inhibition in young and old people.

Three experiments examined whether elderly people perform similarly to Korsakoff amnesics on tests of release from proactive inhibition (PI). In Exp I, with 20 18–36 yr old undergraduates, 20 64–77 yr old university alumni, 20 employed 21–43 yr olds, and 21 institutionalized but healthy 71–92 yr olds, only the latter Ss failed to release from PI, like Korsakoff amnesics, whereas all the other groups of Ss showed the normal release from PI. Exp II, with 12 institutionalized 64–90 yr olds and 12 25–47 yr old controls, showed that release from PI could be induced in institutionalized elderly, as in Korsakoff amnesics, by salient environmental cues that coincided with the category shift. Exp III, with 13 67–89 yr old institutionalized Ss and 12 22–42 yr old controls, demonstrated that even in the absence of a category shift, salient environmental cues could lead to smaller, but noticeable, release from PI in institutionalized elderly, but not in young controls. The similarity in performance between the institutionalized elderly and Korsakoff amnesics suggested that it results from a common neurological deficit. (French abstract) (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Politeness and conditional reasoning: Interpersonal cues to the indirect suppression of deductive inferences.

A successful theory of conditional reasoning requires an account of how reasoners recognize the pragmatic function a conditional statement is meant to perform. Situations in which it is ambiguous whether a conditional statement was meant to add information or to correct a mistake are discussed in this article. This ambiguity has direct consequences on the way reasoners update their beliefs and derive conclusions. In an analysis of ambiguity from the perspective of politeness theory, the authors suggest that any contextual factor that increases the face threat of a correction will encourage reasoners to construe the ambiguous conditional as a correction. This construal will impact their beliefs about the piece of information that is ambiguously corrected, and their beliefs will affect the deductive conclusions they are willing to draw. This nested mediation structure was observed in 2 experiments. The first experiment manipulated the threat level of a correction through the portrayed personality of the person being corrected; the second experiment manipulated the affective distance between the corrector and the corrected. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electrophysiological evidence for a shared representational medium for visual images and visual percepts.

Systematic effects of imagery on visual signal detection performance have been used to argue that imagery and the perceptual processing of stimuli interact at some common locus of activity (Farah, 1985). However, such a result is neutral with respect to the question of whether the interaction occurs during modality-specific visual processing of the stimulus. If imagery affects stimulus processing at early, modality-specific stages of stimulus representation, this implies that the shared stimulus representations are visual, whereas if imagery affects stimulus processing only at later, amodal stages of stimulus representation, this implies that imagery involves more abstract, postvisual stimulus representations. To distinguish between these 2 possibilities, we repeated the earlier imagery-perception interaction experiment while recording event-related potentials (ERPs) to stimuli from 16 scalp electrodes. By observing the time course and scalp distribution of the effect of imagery on the ERP to stimuli, we can put constraints on the locus of the shared representations for imagery and perception. An effect of imagery was seen within 200 ms following stimulus presentation, at the latency of the 1st negative component of the visual ERP, localized at the occipital and posterior temporal regions of the scalp, that is, directly over visual cortex. This finding supports the claim that mental images interact with percepts in the visual system proper and hence that mental images are themselves visual representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual perception modifies goal-directed movement control: supporting evidence from a visual perturbation paradigm

It is well known that dynamic visual information influences movement control, whereas the role played by background visual information is still largely unknown. Evidence coming mainly from eye movement and manual tracking studies indicates that background visual information modifies motion perception and might influence movement control. The goal of the present study was to test this hypothesis. Subjects had to apply pressure on a strain gauge to displace in a single action a cursor shown on a video display and to immobilize it on a target shown on the same display. In some instances, the visual background against which the cursor moved was unexpectedly perturbed in a direction opposite to (Experiment 1), or in the same direction as (Experiment 2) the cursor controlled by the subject. The results of both experiments indicated that the introduction of a visual perturbation significantly affected aiming accuracy. These results suggest that background visual information is used to evaluate the velocity of the aiming cursor, and that this perceived velocity is fed back to the control system, which uses it for on-line corrections.     

Short-term memory for reaching to visual targets: psychophysical evidence for body-centered reference frames

Pointing to a remembered visual target involves the transformation of visual information into an appropriate motor output, with a passage through short-term memory storage. In an attempt to identify the reference frames used to represent the target position during the memory period, we measured errors in pointing to remembered three-dimensional (3D) targets. Subjects pointed after a fixed delay to remembered targets distributed within a 22 mm radius volume. Conditions varied in terms of lighting (dim light or total darkness), delay duration (0.5, 5.0, and 8.0 sec), effector hand (left or right), and workspace location. Pointing errors were quantified by 3D constant and variable errors and by a novel measure of local distortion in the mapping from target to endpoint positions. The orientation of variable errors differed significantly between light and dark conditions. Increasing the memory delay in darkness evoked a reorientation of variable errors, whereas in the light, the viewer-centered variability changed only in magnitude. Local distortion measurements revealed an anisotropic contraction of endpoint positions toward an "average" response along an axis that points between the eyes and the effector arm. This local contraction was present in both lighting conditions. The magnitude of the contraction remained constant for the two memory delays in the light but increased significantly for the longer delays in darkness. These data argue for the separate storage of distance and direction information within short-term memory, in a reference frame tied to the eyes and the effector arm.     

Selective preference in visual fixation away from negative images in old age? An eye-tracking study.

Recent studies have suggested that older individuals selectively forget negative information. However, findings on a positivity effect in the attention of older adults have been more mixed. In the current study, eye tracking was used to record visual fixation in nearly real-time to investigate whether older individuals show a positivity effect in their visual attention to emotional information. Young and old individuals (N = 64) viewed pairs of synthetic faces that included the same face in a nonemotional expression and in 1 of 4 emotional expressions (happiness, sadness, anger, or fear). Gaze patterns were recorded as individuals viewed the face pairs. Older adults showed an attentional preference toward happy faces and away from angry ones; the only preference shown by young adults was toward afraid faces. The age groups were not different in overall cognitive functioning, suggesting that these attentional differences are specific and motivated rather than due to general cognitive change with age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Decomposing visual search: evidence of multiple item-specific skills

Four experiments demonstrated that visual search can be decomposed into two components: one consisting of skills shared with memory search and the other consisting of skills not shared with memory search. A training-transfer paradigm was used to test for transfer from memory search to visual search and vice versa. When the same targets and distractors were used in training and transfer, visual search practice completely trained memory search, but memory search practice only partially trained visual search. Learning on both the shared and the private components of visual search benefited more from item-specific training than from nonspecific training. The relationship between the components and some theorized models of visual search are discussed, particularly in terms of prioritization learning.     

Excitatory-inhibitory network in the visual cortex: psychophysical evidence

At early stages in visual processing cells respond to local stimuli with specific features such as orientation and spatial frequency. Although the receptive fields of these cells have been thought to be local and independent, recent physiological and psychophysical evidence has accumulated, indicating that the cells participate in a rich network of local connections. Thus, these local processing units can integrate information over much larger parts of the visual field; the pattern of their response to a stimulus apparently depends on the context presented. To explore the pattern of lateral interactions in human visual cortex under different context conditions we used a novel chain lateral masking detection paradigm, in which human observers performed a detection task in the presence of different length chains of high-contrast-flanked Gabor signals. The results indicated a nonmonotonic relation of the detection threshold with the number of flankers. Remote flankers had a stronger effect on target detection when the space between them was filled with other flankers, indicating that the detection threshold is caused by dynamics of large neuronal populations in the neocortex, with a major interplay between excitation and inhibition. We considered a model of the primary visual cortex as a network consisting of excitatory and inhibitory cell populations, with both short- and long-range interactions. The model exhibited a behavior similar to the experimental results throughout a range of parameters. Experimental and modeling results indicated that long-range connections play an important role in visual perception, possibly mediating the effects of context.     

Selective processing of visual alcohol cues in abstinent alcoholics: an approach-avoidance conflict?

When symptomatic individuals selectively attend to emotionally relevant stimuli, the ability to shift attention away from such material is impaired. Subjects may, however, seek to avoid further processing of these stimuli, which would facilitate attentional shifts. This was examined in a group of abstinent alcoholics' responses to stimuli related to alcohol. Eight alcohol and eight neutral words served as cues in a covert attention task. The cues were either valid (2/3 of trials) or invalid (1/3 of trials) indicators of where a response target would appear after 100 or 500 milliseconds. The short interval was expected to interact with an initial approach toward the alcohol word, while the long interval would interact with a subsequent avoidance of the stimulus. As predicted, the alcoholics showed slower reaction times (RTs) to targets invalidly cued by alcohol words in the short interval, reflecting increased difficulties to shift attention. However, the alcoholics demonstrated faster RTs to targets invalidly cued by the alcohol words in the long interval. This indicates that the alcohol cue elicited emotional associations that, subsequent to initial stimulus identification, trigger an interrupting function of the attentional system.     

Sepsis-induced vasoparalysis does not involve the cerebral vasculature: indirect evidence from autoregulation and carbon dioxide reactivity studies

We have studied cerebral autoregulation and vasoreactivity to carbon dioxide in 10 patients with the sepsis syndrome receiving intensive therapy. All patients were sedated with infusions of midazolam and fentanyl, and their lungs were ventilated mechanically with oxygen-air to maintain normoxia and normocapnia. Inotropic support and antibiotics were administered as necessary. During a period of constant level of sedation and stable haemodynamics, cerebral autoregulation was tested by increasing mean arterial pressure (MAP) by 23 (SD 2) mm Hg from baseline with an infusion of phenylephrine and simultaneously recording middle cerebral artery blood flow velocity (vmca) using transcranial Doppler ultrasonography. Carbon dioxide reactivity was tested by varying PaCO2 between 3.0 and 7.0 kPa and simultaneously recording vmca. There was no significant change in vmca (57 (22) and 59 (23) cm s-1) during the increase in MAP (75 (11) to 98 (10) mm Hg). The mean index of autoregulation (IOR) was 0.92 (SEM 0.03), which was not significantly different from 1, indicating near perfect autoregulation. Although absolute carbon dioxide reactivity was lower than reported previously in awake subjects, relative carbon dioxide reactivity was within normal limits for all patients (11.6 (SEM 0.8) cm s-1 and 20.3 (3) % kPa-1, respectively). We conclude that cerebral carbon dioxide reactivity and pressure autoregulation remained intact in patients with the sepsis syndrome, providing indirect evidence that at least in the early stages of the syndrome, the widespread sepsis-induced vasoparalysis does not involve the cerebral vasculature.