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J F Juola

Publications and source records attributed to J F Juola.

At least 19 recordsLinked to original sources
PubMed2001

Relative roles of 3-D and 2-D coordinate systems in solving the correspondence problem in apparent motion.

There has been a controversy in the apparent motion literature regarding the influence of 3-D distances between motion tokens on correspondence matching. The current series of experiments indicates that this discrepancy results because the effect of three-dimensional distance is too small to be detected unless the retinal coordinates of the motion tokens are carefully chosen so as to lead to ambiguous correspondence matches on identical trials. It is also shown that, even when the retinal coordinates of motion tokens are equated, such that the different solutions to the correspondence problem are generated with equal probability, the effect of 3-D distances obtained is relatively small when compared to the effect of the retinal coordinates of motion tokens.

Depth Perception↗
PubMed2000

Evidence for distinct attentional bottlenecks in attention switching and attentional blink tasks.

E. Weichselgartner and G. A. Sperling (1987), using rapid serial visual presentation (RSVP), estimated that attention could be moved to a new spatial location within 300-400 ms. H. J. Müller and P. M. Rabbit (1989) used a spatial cuing task and found a similar time course for voluntarily redeploying attention. A separate phenomenon known as the attentional blink (AB) also follows a similar time course, yet occurs when participants attend to a single spatial location. The present study found that attention can be shifted more quickly than previously estimated and that part of the deficit observed during searches of spatially distinct RSVP streams is due to an AB. The results support some early and late selection accounts for the temporal dynamics of visual attention and suggest different bottlenecks during visual selection. The implications for visual search and visual processing are discussed.

Attention↗
PubMed2000

Automatic and voluntary control of attention in young and older adults.

Young and older adults searched for a target character in a 3-item display. On each trial, both a symbolic cue (arrow at fixation) and a spatial cue (abrupt onset of one item) could indicate the target's position. Participants were told to use the central arrow cue on all trials because it had 75% validity. The onset cue also had 75% validity for half the participants and 25% validity for the other half. Both age groups showed about the same cost and benefit effects for the central arrow cues, but the abrupt onsets had much larger cuing effects for older adults. Young adults were able to suppress at least partially an automatic attentional response to an abrupt onset item when the arrow cue preceded the onset and had a higher validity than the onset cue. Older adults appeared to be less able to inhibit their responses to abrupt onsets and to disengage their attention from invalid onset cues than were the young adults.

Adult↗
PubMed1997

Strategic reliance on phonological mediation in lexical access.

The present study investigated strategic variation in reliance on phonological mediation in visual word recognition. In Experiment 1, semantically related or unrelated word primes preceded word, pseudohomophone (e.g., trane), or nonpseudohomophone (e.g., trank) targets in a lexical decision task. Semantic priming effects were found for words, and response latencies to pseudohomophones were longer in related than in unrelated prime conditions. In Experiment 2, related or unrelated word primes preceded word or pseudohomophone targets. A relatedness effect was found for words, although it was significant at a 600-msec prime-target stimulus onset asynchrony (SOA) and not at a 200-msec SOA. There was no relatedness effect for pseudohomophones. Experiment 3 was a replication of Experiment 2, except that pseudohomophones were replaced by nonpseudohomophonic orthographic controls. Facilitation effects for related target words were greater in Experiment 3 than in Experiment 2. The results reflect apparent variations in the expectation that a related prime reliably indicates that a target is a word. Although reliance on phonological mediation might be strategically contingent, there could be a brief time period in which phonologically mediated lexical access occurs automatically. Whether phonological information is maintained or suppressed subsequently depends on its overall usefulness for the task.

Adolescent↗
PubMed1995

Reading text presented on a small display.

There are a number of applications in consumer and industrial product environments in which there is a need to display a message in a restricted space. Two general display methods were compared in the present research using an eight-character horizontal display. Text appeared either as a sequence of small right-to-left jumps ('leading'), or as a sequence of whole or part-word patterns (rapid serial visual presentations, RSVP). Upper-case versus lower-case letters and slow (171 words per minute, wpm) versus fast (260 wpm) presentation rates were compared. In all conditions, sentences were read more accurately in the RSVP format than in the leading format. Recommendations for future displays of verbal messages are discussed.

Journal Article↗
PubMed1995

Age changes in the distribution of visual attention.

Two experiments examined adult age differences in the controlled allocation of visual selective attention. Both experiments were identical with the exception of the stimulus display where targets and distractors were linearly increased with eccentricity in Experiment 2. A spatial cuing task was used with four cue-target presentation intervals (SOAs) of 250, 500, 1000, and 2000 msec (Experiment 1) and 250, 500, 750, and 1000 msec (Experiment 2). Results were fit to three quantitative models based on attentional distribution metaphors (spotlight, zoom lens, and ring) in order to determine the best fitting model of attentional distribution. Data from Experiment 1 indicated that older subjects distributed attention in a qualitatively different manner than younger subjects and suggested a different time course of processing. When stimuli visibility was controlled a single flexible resource allocation (ring) model of attention could account for the results of both age groups at all SOAs. Results further suggested that older adults employ compensatory strategies to offset visual processing difficulties.

Adult↗
PubMed1995

Tradeoffs between attentional effects of spatial cues and abrupt onsets.

We determined the relative effectiveness and tradeoffs among central, peripheral, and abrupt onset cues in directing attention to a potential target character. Central cues were arrows located at the fixation point, whereas peripheral cues were arrows occurring about 3 degrees away from fixation, near the location of a potential target. These were contrasted with the abrupt onset of an ambiguous part of a character, which later was filled in to reveal a target or a distractor item. Each trial included an arrow cue and an abrupt onset cue, and both expected cue validities and cue-character SOAs were varied factorially. The results showed that, in general, abrupt onsets captured attention more effectively than either central or peripheral arrow cues. However, tradeoffs among separate cue effects indicated that the power of abrupt onsets to capture attention automatically could be overridden by a high-validity spatial cue presented in advance of the onset character. Tradeoffs between the effects of central and abrupt onset cues were additive, indicating that endogenous and exogenous cues have their main effects at different levels in the visual attention system. Peripheral cues and abrupt onsets showed mainly interactive effects, however, consistent with the idea that both types of cues have exogenous components that affect a common pool of attentional resources.

Adolescent↗
PubMed1992

Relative effectiveness of central, peripheral, and abrupt-onset cues in visual attention.

The relative effectiveness of central arrow, peripheral arrow, and abrupt-onset cues was assessed in a character recognition task. On each trial, either a central or a peripheral arrow cue was presented 0, 100, or 200 msec before the appearance of a three-digit display. Two of the digits were "uncamouflaged" from previous figure-eight masks, whereas the third digit appeared abruptly in a previously empty space. Four different groups of subjects were run in factorial combinations of high or low expected validities for arrow and onset cues. In Experiment 1, arrow cues were located centrally, near the fixation point. Abrupt onsets showed larger cost-plus benefits than central arrows, except when subjects expected the central cues to have higher validity than the onsets. In Experiment 2, arrow cues were located peripherally, near the display digits, and abrupt onsets were again more effective in capturing attention except when peripheral cues had higher validity and led the onsets by 100 msec or more. In both experiments, the relative effectiveness of abrupt onsets decreased with arrow SOA. The results were consistent with a model in which automatic and voluntary processes interact in their control of attentional resources.

Adolescent↗
PubMed1991

Control of attention around the fovea.

Three experiments tested young adults' abilities to use size and location cues to find and identify a target letter in a visual field containing 8 to 12 letters. Location cues (relatively near to or far from the fovea) and size cues (relatively large or small) were given before the display. Compared with response times on neutral, no-cue trials, location and size cues produced independent cost and benefit effects. The best fitting quantitative models allow attentional resources to be distributed in ringlike areas varying in distance from the fixation point, within which further selection of items by their relative size is possible.

Adult↗
PubMed1990

The control of visual attention using multiple target features.

An experiment was conducted to determine how visual attention is allocated in response to pairwise combinations of location, color, and size cues. Subjects viewed displays of eight letters arranged into an 'X' pattern emanating from a central fixation point. The letters varied on the dimensions of location (foveal or parafoveal positions), size (large or small), and color (red or blue). Seven of the letters were 'X's and the remaining, critical letter was either an 'R' or an 'L'. Subjects were given advance cues about characteristics of the critical letter on two of the three dimensions (location size, and color). The cues varied in their validity such that on any trial either both dimensions were validly cued, one dimension was validly cued while the other was invalidly cued, or both cues were invalid. Subjects were instructed to try to use the cues to find the critical letter, and response times to identify it as an 'R' or an 'L' served as the main dependent measure. Two models were evaluated against the data; in one, location cues are viewed as having distinct effects on an early stage of attention whereas color and size cues operate only in a later, selection stage. In the other model, all cues are used in a similar way to select display items for serial, focal attention. In general, the serial processing model provides a more complete account of the data.

Adult↗
PubMed1990

Voluntary allocation versus automatic capture of visual attention.

Is there a difference in the kind of attention elicited by an abrupt-onset peripheral cue and that elicited by an instruction (e.g., a central arrow cue) to move attention to a peripheral location? In Experiment 1, we found that peripheral cues are no more effective in orienting attention than are central cues. No evidence was found for separable attentional systems consisting of a volitional response to central cues and an automatic response triggered only by peripheral cues. Rather, an identical or similar attentional process seems to be activated by either type of cue, although perhaps in different ways. Peripheral cues seem to have an automatic component, however, in that once attention is engaged by a peripheral cue, it cannot easily be disengaged for refocus elsewhere. In Experiment 2, after several sessions of practice, subjects were able to circumvent automatic attentional capture by an abrupt-onset peripheral cue and to volitionally redirect the focus of attention. Thus, attentional capture by abrupt-onset stimuli is not strongly automatic.

Adult↗
PubMed1982

Reading with and without eye movements: reply to Just, Carpenter, and Woolley.

Just, Carpenter, and Woolley propose that measures of single-word processing times, such as gaze durations during normal reading or durations of reader-controlled exposures, can be used both for developing theories of comprehension and for determining the course of new reading technologies. We argue that better understanding of comprehension processes does not necessarily follow from observed correlations between text variables and eye-fixation parameters. Further, recent rapid serial visual presentation (RSVP) research suggests that eye fixation data obtained from studies of normal reading might have little practical value in optimizing the readability of RSVP displays and other means of text presentation.

Eye Movements↗
PubMed1979

Cognitive loci of impairments in picture naming by aphasic subjects.

In order to identify the process or processes responsible for impaired naming by aphasic patients, ten aphasic adults and ten normal adults performed three independent tasks--picture naming, modified Sternberg picture recognition, and modified Sternberg random shape recognition (Sternberg, 1966). Response times and error percentages were the dependent variables. Independent variables in naming were stimulus codability measured in bits of uncertainty (two levels) and number of naming trials (three trials). Independent variables in the recognition tasks were uncertainty (two levels), number of stimuli to be remembered (two or four stimuli) and response type ("yes" or "no"). The results showed that uncertainty had significant effects on naming but not on recognition performance. The aphasic group produced significantly longer naming response times regardless of uncertainty level. The differences between groups were much greater for high-uncertainty pictures (1100 msec) than for low-uncertainty pictures (270 msec). A comparison of estimates of word retrieval times showed that the two subject groups differed significantly for high-uncertainty but not for low-uncertainty items. It was concluded that (1) use of the term "word retrieval problem" rather than "loss of memory problem" was justified to describe the major component in the aphasic naming impairment for high-uncertainty items, and (2) when naming low-uncertainty items these aphasic subjects did not demonstrate a word retrieval problem. The results indicate that treatment procedures designed to improve naming should be process rather than content oriented.

Adult↗