Biomedical subjects

M Cheal

Publications and source records attributed to M Cheal.

At least 19 recordsLinked to original sources

PubMed2001

Attentional capture with various distractor and target types.

Effects of nonpredictive distractors that involved changes in luminance, size, or shape were examined in three experiments. In Experiment 1, with two types of distractors (onsets and offsets), accuracy was better on trials when the distractor was near the location of either an offset or an onset target than on trials when the distractor was in a different location from that of the target, demonstrating attentional capture. Capture occurred both when the type of target (onset or offset) was blocked and therefore predictable and also when the type of target was mixed within blocks and therefore not predictable. Further experiments indicated that distractors captured attention even when the change to distractor did not create a new perceptual object. Neither a singleton-detection mode, nor a contingent involuntary orienting hypothesis, nor creation of a new object seems to explain all of these data adequately. Rather, capture may depend on a number of factors in the task.

Adolescent↗

PubMed2001

Allocation of visual attention depends on type of precue.

To distinguish between theoretical concepts of how attention is allocated, participants were presented with different types of precues in 6 experiments. In 1 condition with 100% valid precues (Experiments 1 and 2), the time course of attention effects revealed that (a) higher accuracy was obtained with dynamic multiple-element precues (MEPs in which the unique element was defined by apparent motion) than with static MEPs, in which the elements did not move once they were presented (Cheal & Chastain, 1998); (b) a longer precue-target interval (stimulus-onset asynchrony; SOA) was needed to reach asymptote accuracy with dynamic MEPs than with dynamic single-element precues (SEPs); and (c) all dynamic precues (both MEPs and SEPs) resulted in a decline in accuracy at long SOAs. These results suggest that static and dynamic MEPs result in delayed engagement of attention relative to SEPs. Further, a decline in accuracy at long intervals is associated with static and dynamic SEPs and dynamic MEPs, but not with static MEPs. With irrelevant precues (Experiments 3 to 5), there was capture by precues in which the unique element moved briskly, smoothly, or abruptly, or simply flashed on and off, although there were differences in the amount of capture. The strongest capture occurred with smooth movement in static background elements and the weakest with smooth movement in abruptly moving background elements. It was shown in Experiment 6 that a static MEP will not capture attention if one element changes to a unique brightness near the time of precue onset, but if the element changes after 1,000 ms, it will capture attention. The authors suggest that different types of precues result in unequal influence of endogenous and exogenous components of attention, even when the same targets are used. In addition, they show that neither singleton detection mode nor contingent involuntary orienting is necessary for the capture of attention.

Adolescent↗

PubMed1999

Inhibition of return: support for generality of the phenomenon.

Inhibition of return (IOR), first described in 1984, was considered to be a general phenomenon for ensuring that attention would be allocated to successive stimuli in the environment. In the present research, IOR was expressed in forced-choice identification tasks with either reaction time or accuracy as the dependent measure. Thus, the generality of IOR was supported, because response inhibition cannot explain IOR found with accuracy measures. Concepts from the variable and permeable filters metaphor are used to suggest how changes in attention can change expression of IOR by rapid variation in perceptual threshold.

Adolescent↗

PubMed1999

Time course of attention effects with abrupt-onset and offset single- and multiple-element precues.

Large differences between the time course of attentional responsiveness to onset single-element precues (onset singles) and to onset multiple-element precues (onset multiples) have suggested differences in the way attention is controlled. In five experiments here, singles presented as offsets produced rapid attention buildup, attentional decay across longer precue-to-target delays, and attentional capture, as do onset singles, suggesting exogenous attentional control; both offset and onset multiples produced gradual onset of attentional effects without subsequent attentional decay, suggesting endogenous attentional control; and onset and offset singles produced higher accuracy than onset and offset multiples. Thus, the dynamic quality of a sudden onset is not sufficient explanation for the exogenous attentional control produced by a single-element peripheral precue.

Adult↗

PubMed1998

Attention effects of moving and stationary single-element and multiple-element precues: limits of automaticity.

A multiple-element precue (MEP), in which one unique element defines the actual precue, results in efficient precuing for identification of a target. The time course for identification in this case is similar to that for a central precue, even though it is presented peripherally (Chastain, 1996; Chastain & Cheal, in press). Five experiments were conducted to gain further information on the function of MEPs and to question what advantage prior knowledge of the precue may give. In Experiments 1 and 2, it was shown that for "pop-out" features, accuracy of identification of a target was higher if the precue type was known in advance. In contrast, as shown in Experiments 3, 4, and 5, when the precue was defined by apparent motion, there was no difference in accuracy due to advanced knowledge of the precue. Further, accuracy was considerably better for motion precues than for stationary precues.

Attention↗

PubMed1997

Facilitatory or Inhibitory Nontarget Effects in the Location-Cuing Paradigm

The effect of nontargets on the identification of targets in the location-cuing paradigm was investigated in order to determine whether observers consistently allocate their attention to a validly cued location and whether the effect of nontargets is to facilitate or to inhibit performance. In four experiments, the effects of a single matching nontarget or a single nonmatching nontarget were compared. In each experiment, it was shown that observers consistently allocate their attention to a cued location when a precue appears and that performance is inhibited more by nonmatching nontargets in the display than it is facilitated by matching nontargets.

Journal Article↗

PubMed1997

Understanding Diverse Effects of Visual Attention with the VAP-Filters Metaphor

The Variable and Permeable Filters (VAP-Filters) metaphor is presented with an explanation of its advantages over other popular metaphors in accounting for attention effects in many different research paradigms. Research from laboratories of the author and others are discussed briefly and shown to result in diverse facilitatory and inhibitory attention effects on visual perception. All of these effects are consistent with the VAP-Filters metaphor.

Journal Article↗

PubMed1996

Attention and nontarget effects in the location-cuing paradigm.

Three experiments were conducted in order to determine whether irrelevant items presented outside the focus of attention would affect the identification of a precued target. A peripheral cue indicated one of eight possible locations in a circular array, centered on fixation with a radius of 5.25 degrees. After a variable interval (0-200 msec), eight characters were presented briefly and masked. In each experiment, there was an effect of the identity of the characters at the seven noncued locations (the nontargets) on the accuracy of identification of the target. When there were more nontargets identical to the target, accuracy was higher than when there were fewer nontargets identical to the target. Nontargets consistently affected performance despite incentives to focus only on the target.

Adult↗

PubMed1994

Allocation of attention in texture segregation, visual search, and location-precuing paradigms.

Is there a common mechanism (or set of mechanisms) that controls the allocation of spatial attention in texture segregation, visual search, and location-precuing tasks? This question was addressed by comparing data from a new set of experiments on texture segregation, in which a common set of stimuli was used across the three paradigms. However, when we ranked the scores for the targets on texture segregation speed, search rate, and improvement due to precuing effects, agreement between these measures was less than perfect. Further analyses of these results led to the following conclusions: (a) speed of texture segregation is affected by perceptual aspects of the display other than the attentional salience of a particular target; (b) visual search rate and the size of precuing effects are strongly related over most of the set of targets we used; and (c) some cases in which search rate was not consistent with size of precue effects may be related to the presence of nearby distractors in the search task.

Adult↗

PubMed1992

Attention in visual search: multiple search classes.

Data from visual-search tasks are typically interpreted to mean that searching for targets defined by feature differences does not require attention and thus can be performed in parallel, whereas searching for other targets requires serial allocation of attention. The question addressed here was whether a parallel-serial dichotomy would be obtained if data were collected using a variety of targets representing each of several kinds of defining features. Data analyses included several computations in addition to search rate: (1) target-absent to target-present slope ratios; (2) two separate data transformations to control for errors; (3) minimum reaction time; and (4) slopes of standard deviation as a function of set size. Some targets showed strongly parallel or strongly serial search, but there was evidence for several intermediate search classes. Sometimes, for a given target-distractor pair, the results depended strongly on which character was the target and which was the distractor. Implications from theories of visual search are discussed.

Adult↗

PubMed1991

Importance of precue location in directing attention.

In location-precuing experiments, accuracy in discrimination of T-like characters improves with increasing time between the precue and the target. In this experiment, two central and two peripheral cue locations were examined using 13 different cue-target intervals from 0 to 234 msec. Accuracy was the same when trials were cued from the two peripheral locations (two thirds distance between fixation and target or distal to the target location). Centrally cued trials (cues at fixation or next to fixation) resulted in slower onset of attentional effects than peripherally cued trials, but there was greater accuracy at long cue-target intervals for central than for peripheral cues. Data are compared to previously published research.

Attention↗

PubMed1991

Does attention have different effects on line orientation and line arrangement discrimination?

Visual search and texture segregation studies have led to the inference that stimuli differing in the orientation of their component line segments can be distinguished without focal attention, whereas stimuli that differ only in the arrangement of line segments cannot. In most of this research, the locus of attention has not been explicitly manipulated. In the first experiment presented here, attention was directed to a relevant peripheral target by a cue presented near the target location or at the fovea. Effects of attention on orientation discrimination were assessed in a two-alternative forced-choice task with targets that were either: (1) lines that slanted obliquely to the right or left, or were horizontal or vertical, or (2) Y-like targets that had a short arm leading obliquely right or left of a vertical line. In some groups, a four-alternative forced-choice test with lines at 0 degree, 45 degrees, 90 degrees, and 135 degrees orientations was used. Discrimination of these targets (i.e. targets that differ in the orientation of component line segments) was only minimally facilitated as the time between the onset of the valid cue and the onset of the target (cue-target stimulus onset asynchrony, SOA) was increased from 0 or 17 msec to 267 msec. In contrast, discrimination of targets that did not differ in the orientation of component line segments but differed in line arrangement (T-like characters), was greatly facilitated by longer cue-target SOAs. In Experiment 2, a cue misdirected attention on 20% of the trials. A decrement occurred on incorrectly cued trials in comparison to correctly cued trials for both types of stimuli used (lines and Ts). The results from these experiments suggest that discrimination of line orientation benefits less from focal attention than does discrimination of line arrangement, but that both discriminations suffer when attention must be disengaged from an irrelevant spatial location.

Adult↗

PubMed1991

Central and peripheral precuing of forced-choice discrimination.

There are suggestions in the literature that spatial precuing of attention with peripheral and central cues may be mediated by different mechanisms. To investigate this issue, data from two previous papers were reanalysed to investigate the complete time course of precuing target location with either: (1) a peripheral cue that may draw attention reflexively, or (2) a central, symbolic cue that may require attention to be directed voluntarily. This analysis led to predictions that were tested in another experiment. The main result of this experiment was that a peripheral cue produced its largest effects on discrimination performance within 100 msec, whereas a central cue required approximately 300 msec to achieve maximum effects. In conjunction with previous findings, the present evidence for time differences between the two cuing conditions suggests that more than one process is involved in the spatial precuing of attention.

Adult↗

PubMed1987

Environmental enrichment facilitates foraging behavior.

Mongolian gerbils (Meriones unguiculatus) were tested at 24 months of age after having experienced an outdoor desert environment for one hour each month after weaning, or at 8 months of age after being reared from birth in outsize cages in the laboratory. Both groups of enriched gerbils found food more rapidly than did 24-month-old handled controls, 8-month-old naive gerbils, or 8-month-old gerbils reared in small cages. There were no differences in locomotor activity, in latency to emerge from a small box, or in attention to novel objects or conspecific odors. Efficiency in finding food was not associated with types of food chosen, and the foods selected were not directly related to types of food eaten previously.

Animal Husbandry↗

PubMed1987

Attention and habituation: separation of specific components in development.

In four experiments using habituation procedures, it was shown that selective investigation of stimuli that are novel gradually developed between 13 and 28 days of age in gerbil pups. The youngest pups investigated the stimuli, but were highly variable in their responses to an object or to odors of conspecifics. Habituation could, but did not reliably, occur. By 21 days of age, investigation of a cup attenuated in a series of 5 one-minute trials and responses increased after the cup was moved to a new location. By 28 days of age, reliable habituation was shown 24 hours after a one-minute exposure to a cup. The data were used to infer how an immature process of selective attention may be responsible for variability in expression of habituation during development.

Aging↗

PubMed1986

Brief periods of environmental enrichment facilitate adolescent development of gerbils.

In a lifespan study, measures of motor behavior and somatic growth were recorded monthly from 31 male and 31 female gerbils. Each month, after measures were recorded, the gerbils were placed in a large, outdoor environment, or in a small indoor control cage for one hour. The enrichment experience for one hour a month had no effect on motor behavior between 2 and 7 months of age, but facilitated adolescent development. Area of the ventral gland increased more rapidly in gerbils given environmental enrichment. In male gerbils, the hindlimb was longer in those given environmental enrichment, but the opposite was true in female gerbils. More female gerbils had seizures than did male gerbils after 3 months of age, and enrichment had no significant effect on seizures in female gerbils. In male gerbils, however, more of the gerbils given enrichment experience had seizures from 2 to 4 months of age and fewer had seizures at 5 and 6 months of age than did controls.

Animals↗

PubMed1984

Differential effects of haloperidol and clozapine on attention.

Haloperidol (0, 0.1, 0.3, or 1.0 mg/kg), the typical butyrophenone neuroleptic, decreased investigation of novel objects by gerbils following systemic injections. When given prior to apomorphine (1 or 3 mg/kg), haloperidol blocked apomorphine-induced disruption of selective attention in a dose-dependent manner. Thus, haloperidol acts like pimozide in this paradigm. In contrast, clozapine (0, 0.03, 0.1, 0.3, 1.0, or 3.0 mg/kg), the atypical dibenzodiazepine neuroleptic, increased frequency of investigation both soon after injection and 24h later, suggesting interference with maintenance of attention. When given with apomorphine (1.0 mg/kg), clozapine did not block apomorphine effects on selective attention. The results are related to differential effects of these neuroleptics on other behaviors and to their individual pharmacological profiles.

Animals↗

PubMed1983

L-Dopa and piribedil alter different components of attentional behavior dependent on dose.

L-Dopa (3, 10, 30, 100 mg/kg) given SC after carbidopa, and piribedil (10, 30, 100, 300 mg/kg) had biphasic effects on investigation of a novel cup. Gerbils given a low dose of L-Dopa (10 mg/kg) or piribedil (10 or 30 mg/kg) investigated the cup more than did vehicle-injected gerbils, whereas those gerbils given a high dose of L-Dopa (100 mg/kg) or piribedil (300 mg/kg) investigated it less. L-Dopa, but not piribedil, also had biphasic effects on investigation of conspecific odors. The increase in duration with no increase in frequency of investigation suggested an inability to shift attention normally. High-dose attenuation of investigation is considered nonspecific, as many other drugs have the same effect. Locomotor activity scores showed no concomitant increase following low doses, but only a dose-dependent decrease. In addition, L-Dopa (100 mg/kg), but not piribedil at any dose tested, prevented the normal decrement in response to the cup 24 h after injection. As a high response is normally only shown when the stimulus is novel, the data suggest that L-Dopa at the high dose, but not piribedil, interfered with selective attention. Thus, the different dopamine agonists affected different aspects of attention. The data are discussed in relation to neural effects of the drugs as reported in the literature.

Animals↗