Is chimpanzee (Pan troglodytes) spatial attention reflexively triggered by gaze cue?

Humans show a reflexive shift in spatial attention triggered by gaze cues. Chimpanzees (Pan troglodytes) have an excellent ability to follow another's gaze, but they exhibit a limited capacity to engage in triadic interactions based on joint attention, suggesting the possibility of contributions of the different mechanisms underlying joint attention between humans and chimpanzees. The present study thus examined how the chimpanzee's visual spatial attention is triggered by gaze cues. Two chimpanzees showed no clear signs of attention shift triggered by various kinds of nonfacial and facial stimuli with averted gaze under the letter-discrimination tasks but showed significant cueing effects when the head-turning cue was presented in a quasi-dynamic manner. These cueing effects were, however, affected by the predictability of the gaze cue: Highly predictive gaze cues caused stronger cueing effects than less predictive cues. Thus, these results suggest that the shift in spatial attention caused by gaze cues does occur in chimpanzees, but, in contrast to humans, vulnerability against the cue predictability suggests that the voluntary mechanism contributes more dominantly than the reflexive mechanism to this attention shift. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cue search and comparison processes in visual search for letters.

In 2 experiments, each with 16 college students and laboratory staff members, Ss searched 4- and 8-letter arrays for the presence of a T or an F. The position of the target was indicated by a bar marker presented at 1 of 7 stimulus onset asynchronies (SOAs): –200, –25, 50, 125, 200, 275, or 350 msec. In Exp I, SOA conditions were blocked; in Exp II, SOA conditions varied randomly from trial to trial. In both experiments array size and SOA interacted. With 8-letter arrays, reaction time (RT) increased linearly with SOA with a slope less than 1. With 4-letter arrays, RT increased with SOA but reached asymptote at the level of no-cue control RTs at the 125-msec SOA. Results support the notion that cue search and comparison processes may function concurrently. (French summary) (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and shifts of visual spatial attention.

Three experiments examined adult age differences in the efficiency of endogenous (voluntary) and exogenous (involuntary) attention shifts. Younger and older Ss performed a spatial cuing task in which abruptly onset peripheral cues (Exp 1) or central, symbolic cues (Exps 2 and 3) were presented before a target stimulus at intervals ranging from 50 to 250 msec. With peripheral cues, the magnitude of cuing effects was at least as great for older as for younger adults and followed a similar time course. Similar results were obtained with symbolic cues, although cuing effects for older adults varied with cue difficulty. The results suggest that cue encoding may decline with advancing age but that the efficiency of the shift process is preserved. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clever homunculus: Is there an endogenous act of control in the explicit task-cuing procedure?

Does the explicit task-cuing procedure require an endogenous act of control? In 5 experiments, cues indicating which task to perform preceded targets by several stimulus onset asynchronies (SOAs). Two models were developed to account for changes in reaction time (RT) with SOA. Model 1 assumed an endogenous act of task switching for cue alternations but not for cue repetitions. Model 2 assumed no such act. In Experiments 1 and 2, the cue was masked or not masked. Masking interacted underadditively with repetition and alternation, consistent with Model 2 but not Model 1. In Experiments 3 and 4, 2 cues were used for each task. RT was slower for task repetition than for cue repetition and about the same as RT for task alternation, consistent with Model 2 but not Model 1. The results suggest that the explicit task-cuing procedure does not require an endogenous act of control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Examining the role of the fixation cue in inhibition of return.

To clarify the role of the fixation cue in inhibition of return (IOR), the present study compared four conditions: fixation cue immediately after the peripheral cue, in the middle of the stimulus-onset asynchrony (SOA), immediately before the onset of the target, or no fixation cue. With a 200-ms SOA, less IOR was found when the fixation cue was either absent or occurred immediately after the peripheral cue. No differences between the four conditions were found with 400-ms and 800-ms SOAs. These findings suggest that there is a brief period of time in which attention cannot be withdrawn from the peripherally cued location. Once attention has been withdrawn from the peripherally cued location, IOR can be found at short SOAs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Physical and temporal scaling considerations in a robot model of cricket calling song preference

The cerebellum has been implicated in higher cognitive functions including learning, memory, and attention as well as its well-known role in motor programming. Recent studies have suggested that the cerebellum plays a role in shifts of attention. We investigated the contribution of the cerebellum to visuospatial attentional ability in a trial-by-trial cueing task involving the covert orienting of spatial attention. We recorded event-related evoked potentials (ERPs) and reaction times (RTs) in patients with cerebellar degenerative disorders affecting mainly the lateral cerebellum and compared them to age-matched controls. The RT data demonstrated that both the cerebellar patients and control subjects responded to the valid cues faster than to the invalid cues for both the central and the peripheral cues. Consistent with the RT data, the ERP data showed a comparable generation of attention shift-related negativities during the cue-target interval for both the central and the peripheral cue experiments. The early negative component of the ERP to the target was also comparably modulated in both groups as a function of cue validity, suggesting efficient facilitation of sensory pathways by prior allocation of spatial attention to the cued place. Conversely, the late negative deflection preceding the imperative target stimulus and the late sustained positivity following target presentation, which reflect neural activities for response preparation and selection, were reduced in the cerebellar group. These findings suggest that the lateral cerebellum makes little contribution to visuospatial attention shift in either the voluntary or automatic modes and support a role of the lateral cerebellum in the neural system required for response preparation and selection.     

The extension of the interference effect to multiplication.

Investigated the interference effect in the number matching task using multiplication facts. 40 Ss verified the presence of a target number (e.g., 8) in a previously presented cue (e.g., 5 x 8) that was masked after 60 msec. The stimulus onset asynchrony (SOA) between cue and target was 100, 120, 220, and 350 msec. Ss were slower to reject targets that were the product of the cue (e.g., 40) than unrelated targets (e.g., 42) at the 100- and 120-msec SOAs. Findings indicate interference effects at these SOAs and support the hypothesis that the cues activated associated numbers resulting in slower latencies for product than unrelated trials. This pattern is consistent with the interference effect found by J. LeFevre et al (see records 76-00346, 79-04985, and 81-43827) using addition facts. The authors conclude that the interference effect previously found with addition facts was due to obligatory activation and not to automatic counting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic and attentional priming in young and older adults: Reevaluation of the two-process model.

Three experiments addressed the distinction between automatic and attentional mechanisms underlying semantic priming effects by factorially crossing prime–target relatedness, expectancy, and stimulus onset asynchrony (SOA) in a task (pronunciation) that minimized postlexical checking processes. Also, possible age-related (young vs older adults) differences in the automatic and attentional mechanisms were addressed. Across all experiments there was evidence of a Relatedness?×?Expectancy?×?SOA interaction, which is inconsistent with the notion of independent automatic and attentional mechanisms in semantic priming and the notion of a self-incapsulated modular lexicon. The results also indicated age-related differences in the build-up of the expectancy effect across SOAs when the prime was visually available for only 200 msec, independently of the prime–target SOA (Exp 1 and 3), but not when the prime was visually available throughout the SOA (Exp 2). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Supramodal and modality-specific mechanisms for stimulus-driven shifts of auditory and visual attention.

Describes 2 experiments in which visual and/or auditory location precues preceded visual or auditory targets. 30 observers were required to judge the location of the targets. Conditions were such that involuntary, stimulus-driven (SD) attention shifts were the only ones likely to occur and give rise to cueing effects. It was found that visual precues affected response time to localize both visual targets and auditory targets, but auditory precues affected only the time to localize auditory targets. Moreover, when visual and auditory cues conflicted, visual cues dominated in the visual task but were dominated by auditory cues in the auditory task. Results suggest that involuntary SD attention shifts might be controlled by a modality-specific mechanism for visual tasks, whereas SD shifts of auditory attention are controlled by a supramodal mechanism. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention constraints of semantic activation during visual word recognition.

The reduction of semantic priming following letter search of the prime suggests that semantic activation can be blocked if attention is allocated to the letter level during word processing. Is this true even for the very fast-acting component of semantic activation? To test this, the authors explored semantic priming of lexical decision at stimulus onset asynchronies (SOAs) of either 200 or 1000 ms. Following semantic prime processing, priming occurred at both SOAs. In contrast, no priming occurred at the long SOA following letter-level processing. Of greatest interest, at the short SOA there was priming following the less demanding consonant/vowel task but not following the more attention-demanding letter search task. Hence, semantic activation can occur even when attention is directed to the letter level, provided there are sufficient resources to support this activation. The authors conclude that the default setting during word recognition is for fast-acting activation of the semantic system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ten years of experience with the modified Ross procedure

BACKGROUND: Abnormal performance on the antisaccade task suggests that patients with schizophrenia have difficulty with the inhibition of reflexive attentional shifts. The aim of the study was to investigate whether deficits in the inhibition of reflexive attentional shifts were specific to the oculomotor modality or whether they could also occur when attentional shifts were made without eye movements (e.g. covert attentional shifts). METHODS: Fifteen medicated patients with chronic schizophrenia and 15 matched controls performed the antisaccade task and the covert orientating task (COVAT) where the probability of targets appearing at the same location of a peripheral cue was varied so that voluntary and reflexive orientating systems had the same goal (80% probability of target and cued condition) or opposite goals (20% probability of target at cued location). A condition where only reflexive orientating was initiated was also included (50% probability of target at cued location). For each of these conditions the stimulus onset asynchrony (SOA) varied between 150 and 350 ms. RESULTS: Patients with schizophrenia showed normal latency and accuracy for visually guided saccades but increased error rates and latency on the antisaccade task. For the COVAT, patients with schizophrenia were unable to use voluntary orientating strategies to inhibit reflexive shifts of covert attention. On conditions where only reflexive orientating was required or when the goals of the reflexive and voluntary orientating systems were the same, patients with schizophrenia showed normal performance. CONCLUSIONS: These results suggest the reflexive orientating mode is normal in patients with chronic schizophrenia. However, these patients have a reduced ability to utilize the voluntary orientating mode to control or inhibit reflexive orientating. This impairment of voluntary control is evident for both overt and covert attentional shifts.     

Evidence of strategic effects in the modulation of orienting of attention

Two models of visual orienting of attention are frequently described. Voluntary orienting is usually induced by central cues that direct subjects' attention to a given location in the visual space. Automatic orienting is provoked by presentation of peripheral cues. It is shown that automatic orienting induces greater attentional costs and benefits, and is less under a subject's control (Jonides 1981). Furthermore, it is not similarly affected by factors such as signal eccentricity (Umiltà et al. 1991). The present experiment was undertaken to investigate how sensitive automatic orienting produced by peripheral cues is to voluntary modulations of attention. In experiment 1, subjects facing situations daily in which attentional requirements are high, were compared to non-practiced ones. In experiment 2, other groups of practiced subjects facing high or low attentional-demanding situations were tested. In both experiments, subjects were asked to respond to signals, presented in rapid succession, in one of two possible locations in space, on each side of central fixation point. The cue signal automatically oriented attention to one of the two locations in which a first stimulus was presented with 100% probability; 100 ms after the first response (RT1), a second response signal (RT2) was delivered either in the same location (valid condition) or in the opposite location (invalid condition). Four cue probabilities were manipulated for this second stimulus: 100%/0%, 80%/20%, 50%/50%, and 20%/80%. Two eccentricities of 3 degrees and 6 degrees were tested. RT2 data demonstrated that (1) there was no eccentricity effect; (2) the higher the cue probability, the greater were the attentional costs; (3) the attentional effects were smaller in the practiced subjects who faced attention-demanding situations daily, than in the other groups. Put together, these data suggest that automatic orienting of attention can be modulated by voluntary attentional processes, according to cue probability. Furthermore, experienced subjects seem to be able to better distribute their attentional resources in space, with increased task requirements. The adoption of an optimal criterion might lead to the use of a cost minimizing strategy.     

Contributions of the dopaminergic system to voluntary and automatic orienting of visuospatial attention

Visuospatial attention can be directed by voluntary or involuntary control independent of eye movement. The involvement of cortical and subcortical neural structures in this covert orienting mechanism has been studied using neuroimaging and electrophysiological techniques. This study was designed to investigate the role of the dopaminergic system in both voluntary and automatic orienting mechanisms of visuospatial attention. We recorded event-related evoked potentials (ERPs) and reaction time (RT) during a cued priming task in both patients with idiopathic Parkinson's disease (PD) and control subjects. Voluntary and automatic shifts in attention were studied by using central and peripheral cues, respectively. In the experiment using a central cue, the RT data showed that when the cue-target interval was long, PD patients' responses were delayed, and cue validity effects were reduced, whereas in the peripheral cue experiment the validity effects persisted across all trials. The ERPs demonstrated reduced sustained negativities preceding the imperative targets in both the central and peripheral cue experiments in PD patients. Furthermore, during the long cue-target interval in the central cue experiment, PD patients showed reduced attention shift-related negativities (ARNs) at the anterior scalp sites, whereas ARNs were generated widely in the peripheral cue experiment. The ERP findings were consistent with the RT data. These findings suggest that the dopaminergic system may contribute to voluntary and sustained control of visuospatial attention as well as to the neural system for response preparation, whereas automatic control of visuospatial attention is relatively independent of the dopamine system.     

Sustained visual-spatial attention produces costs and benefits in response time and evoked neural activity

This study investigated the simple reaction time (RT) and event-related potential (ERP) correlates of biasing attention towards a location in the visual field. RTs and ERPs were recorded to stimuli flashed randomly and with equal probability to the left and right visual hemifields in the three blocked, covert attention conditions: (i) attention divided equally to left and right hemifield locations; (ii) attention biased towards the left location; or (iii) attention biased towards the right location. Attention was biased towards left or right by instructions to the subjects, and responses were required to all stimuli. Relative to the divided attention condition, RTs were significantly faster for targets occurring where more attention was allocated (benefits), and slower to targets where less attention was allocated (costs). The early P1 (100-140 msec) component over the lateral occipital scalp regions showed attentional benefits. There were no amplitude modulations of the occipital N1 (125-180 msec) component with attention. Between 200 and 500 msec latency, a late positive deflection (LPD) showed both attentional costs and benefits. The behavioral findings show that when sufficiently induced to bias attention, human observers demonstrate RT benefits as well as costs. The corresponding P1 benefits suggest that the RT benefits of spatial attention may arise as the result of modulations of visual information processing in the extrastriate visual cortex.     

List-context effects in evaluative priming.

Evaluative priming effects are often found in the evaluative decision task, in which persons judge the affective connotation (positive vs. negative) of a target word. The present experiments examined list-context effects to test whether evaluative and semantic priming follow the same laws. In Experiment 1, evaluative priming was found at prime-target stimulus onset asynchronies (SOAs) of 0 ms and 100 ms, but not at SOAs of -100, 200, 600, and 1,200 ms. Experiment 2 manipulated SOA (0, 200, and 1,200 ms) and the proportion (25%, 50%, and 75%) of the prime-target pairs that were evaluatively related. Contrary to the typical finding that increases in the proportion of related prime-target pairs lead to increased priming at long but not short SOAs, an effect of consistency proportion was found at SOAs of 0 ms (for reaction times) and 200 ms (in the accuracy data), but not at the 1,200-ms SOA. The pattern of results is discussed in relation to possible explanatory mechanisms of evaluative priming. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Processing phonological and semantic ambiguity: Evidence from semantic priming at different SOAs.

Disambiguation of heterophonic and homophonic homographs was investigated in Hebrew using semantic priming. Ambiguous primes were followed by unambiguous targets at 100 msec, 250 msec, and 750 msec stimulus onset asynchrony (SOA). Lexical decision for targets related to the dominant phonological alternatives of heterophonic homographs was facilitated at all SOAs. Targets related to subordinate alternatives were facilitated only at SOAs of 250 msec or longer. When the primes were homophonic homographs, semantic relationship facilitated lexical decision to targets at all SOAs regardless of the dominance of the meaning to which the targets were related. These data can be accounted for by assuming multiple lexical entries for heterophonic homographs, single lexical entries for homophonic homographs, and phonological mediation of accessing meanings. Language-specific factors probably account for the long-lasting activation of subordinate meanings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual lexical access is initially phonological: I. Evidence from associative priming by words, homophones, and pseudohomophones.

In 9 experiments, a target word (e.g., frog) was named following an associate ({TOAD}), or a word (e.g., {TOWED}) or nonword (e.g., {TODE}) homophonic with the associate. At brief (e.g., 50 msec) stimulus onset asynchronies (SOAs), the 3 primes produced equal associative priming. At a long SOA (250 msec), priming by {TOAD} was matched by {TODE} but not by {TOWED}. Equal priming at brief SOAs by the 3 primes and no priming by orthographic controls ({TOLD}, {TORD}) suggests that lexical access is initially phonological. {TOWED} priming less than {TODE} at SOA?=?250 msec suggests that phonologically activated representations whose input orthography does not match the addressed spelling (available only for words) are eventually suppressed. Phonological constraints on lexical access precede and set the stage for orthographic constraints. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adult age differences in memory-driven selective attention.

Investigated the ability of young and elderly adults to use memory-driven selective attention in 2 visual-search experiments. In Exp I, 16 18–22 yr olds and 16 60–74 yr olds were Ss in a yes–no search paradigm. Stimulus-onset-asynchrony (SOA) was varied from 200 to 1,000 msec. In Exp II, 18 18–24 yr olds and 18 60–73 yr olds were presented 1 of 2 target letters as a cue, using the same SOA ranges. Results in both experiments show that both age groups exhibited faster RTs to a visual display on trials when advance information (a cue) correctly predicted the particular target letter that would most likely be present in the display. Variations in the SOA between the cue and the display demonstrated that both age groups were capable of developing this selective preparation for a particular target letter within 200 msec. Results indicate that age differences in performance were determined primarily by quantitative changes in the speed of information processing rather than by qualitative changes in attention. In both experiments, the 2 age groups differed in the type of relationship between speed and accuracy that they adopted, suggesting a possible age difference in performance strategy. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual-motor expectancies interact with covert visual orienting under conditions of endogenous but not exogenous control.

Investigated whether the interaction between endogenous cueing and stimulus/response (S/R) would be obtained if attention was controlled exogenously, using 16 Ss. Central and peripheral cues were used to endogenously or exogenously direct the S's attention to the location at which an increase or decrease in the size of a peripheral object was most likely to occur. For each S, one size change was more likely to occur than the other, and the task was choice reaction time (RT; expansion/contraction). S/R probability (particular size change) interacted with cue condition (valid, neutral, and invalid) when the cues were central (endogenous), but the 2 variables were additive when the cues were peripheral (exogenous). Data suggest that controlled allocation of attention in response to a peripheral cue involves qualitatively different mechanisms from those associated with endogenous generation of an expectancy. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual offsets facilitate saccadic latency: Does predisengagement of visuospatial attention mediate this gap effect?

Saccadic reaction time (RT) is reduced when a fixation stimulus is extinguished 200 msec before a target appears. An attentional predisengagement theory (APT) may explain this gap effect: When covert attention is engaged (e.g., on fixation), the saccadic system is inhibited and RT is delayed; when the attended stimulus is extinguished, attention is disengaged, the inhibition is removed, and RT is facilitated. In 3 experiments covert attention was endogenously or exogenously cued to an object on the vertical meridian. Onset of a saccadic target on the horizontal meridian could be preceded by the offset of an attended or unattended object. Contrary to APT, RTs were identical after attended and unattended offsets. Results suggest that the gap effect has 2 components, and covert visual attention plays no role. One component is motor system preparation; the other is a fixation offset effect specific to the oculomotor system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)