Preview Conditions Research Articles

Visual search, singleton capture, and the control of attentional set in ADHD

We report the data on effects on visual search of (1) preview displays and (2) singleton targets and distractors in IQ‐matched ADHD and control children. All children showed interference from singleton distractors even when targets never carried singleton values. This interference from singleton distractors increased under preview conditions, indicating that the children then had fewer resources available to control attention. There was also one selective deficit for ADHD children; they showed marked problems in responding to singleton targets following preview displays. This suggests that, in ADHD, there is either a selective delay or an impairment in switching attentional sets (from a negative set to the preview to a positive set to a singleton target). We discuss the implications for understanding both ADHD and the development of selective attention.

Parieto-occipital areas involved in efficient filtering in search: a time course analysis of visual marking using behavioural and functional imaging procedures.

Search for a colour-form conjunction target can be facilitated by presenting one set of distractors prior to the second set of distractors and the target: the preview benefit (Watson & Humphreys, 1997). The early presentation of one set of distractors enables them to be efficiently filtered from search. We report two studies investigating the time course of the preview benefit. In Experiment 1 we use a standard reaction time analysis to show that the benefit has a relatively slow time course; old items need to precede the new set by 600 ms or more in order to be fully filtered from search. Furthermore, the reductions in reaction time across time in the preview condition varied nonlinearly with the display size, suggesting that old items were discounted from search in parallel. In Experiment 2 we examined the neural locus of this filtering effect over time, using positron emission tomography (PET). We show that regions of parieto-occipital cortex are selectively activated in a preview search condition relative to a detection baseline. These regions also increase in activation as the preview interval increases (and search then becomes easier), consistent with them modulating the parallel filtering of distractors from targets in spatial search. Interestingly, the same areas as those activated in preview search were also active in conjunction search relative to its own detection baseline. Thus these regions either modulate parallel filtering in conjunction search too, or they modulate different behavioural functions according to task constraints.

Does Previewing One Stimulus Feature Help Conjunction Search?

We examined the effects of previewing one aspect of a search display, in order to determine what subset of display information is most useful as a prelude to a search task. Observers were asked to indicate the presence or absence of a known target, in a conjunction search where the target was defined by the combination of colour and orientation (a yellow horizontal line presented among yellow vertical and pink horizontal distractors). In the colour preview condition of experiment 1, observers were first shown a 1 s preview of the locations and colours of the search items before the actual search set was presented. That is, search items first appeared as yellow and pink squares for 1 s, which each then turned into yellow and pink oriented lines (in the same locations) which comprised the display to be searched. In the orientation preview condition, observers were first shown a 1 s preview of the locations and orientations of the search items before the actual search display was presented. These two conditions were compared to a control condition consisting of standard conjunction search without any preview display. There was no effect of colour preview; there was a marginal effect of orientation preview, but in the opposite direction from what was expected reaction time increased for orientation preview searches. In experiment 2 these previews were compared to two spatial cueing conditions; in this experiment the colour preview did provide a small amount of help. Finally, in experiment 3 both previews were presented in succession, and increased facilitation was found, in particular when the colour preview preceded the orientation preview. These findings are discussed in relation to the literature, in particular the Guided Search model (Wolfe et al 1989 Journal of Experimental Psychology: Human Perception and Performance 15 419-433; Wolfe 1994 Psychonomic Bulletin & Review 1 202-238).

Exploring selective attention in ADHD: visual search through space and time.

In order to examine the mechanisms mediating selective attention in Attention Deficit Hyperactivity Disorder (ADHD), this study compared the performance of children diagnosed with ADHD to non-clinical controls on a visual search task in three conditions. In the single feature condition, the target differed from distractors in terms of shape only, whilst in the conjunction baseline, the target was defined by shape and colour relative to distractors. In the preview condition, the conjunction stimuli were segmented over time, so that one set of distractors appeared first, followed 1000 ms later by the second set with the target. Although children with ADHD were slower overall than controls, RTs revealed no difference in search mechanisms between groups; for all children, search was more efficient in the single feature and preview conditions than in the conjunction baseline. However, children with ADHD made more errors, especially in the conjunction and preview conditions. Children with ADHD were not impaired in their mechanisms of visual search relative to controls, but their error patterns implied the adoption of a premature response deadline in the conjunction search condition, and an occasional failure to inhibit old items in the preview condition.

Distinct Subsystems for the Parafoveal Processing of Spatial and Linguistic Information during Eye Fixations in Reading

Two experiments examined readers' use of parafoveally obtained word length information for word recognition. Both experiments manipulated the length (number of constituent characters) of a parafoveally previewed target word so that it was either accurately or inaccurately specified. In Experiment 1, previews also either revealed or denied useful orthographic information. In Experiment 2, parafoveal targets were either high- or low-frequency words. Eye movement contingent display changes were used to show the intact target upon its fixation. Examination of target viewing duration showed completely additive effects of word length previews and of ortho-graphic previews in Experiment 1, viewing duration being shorter in the accurate-length and the orthographic preview conditions. Experiment 2 showed completely additive effects of word length and word frequency, target viewing being shorter in the accurate-length and the high-frequency conditions. Together these results indicate that functionally distinct subsystems control the use of parafoveally visible spatial and linguistic information in reading. Parafoveally visible spatial information appears to be used for two distinct extralinguistic computations: visual object selection and saccade specification.

Visual marking inhibits singleton capture

This paper is concerned with how we prioritize the selection of new objects in visual scenes. We present four experiments investigating the effects of distractor previews on visual search through new objects. Participants viewed a set of to-be-ignored nontargets, with the task being to search for a target in a second set, added to the first after 1000 ms. This second set could contain a salient feature singleton, defined in terms of its color, orientation, or both color and orientation. When the singleton was a distractor, search was slowed relative to when there was no singleton. Search was facilitated when the singleton was a target. Interestingly, both the interference and facilitation effects were modulated when the preview shared features with the singleton. Follow-up experiments showed that this reduction of singleton effects was not due to: (i) low-level sensory aspects of the displays, (ii) increased heterogeneity in the search set in the preview condition, or (iii) color-based grouping of old and new items. Instead, we suggest that there is an inhibitory carry-over from the first to the second set of items based on feature similarity. We suggest the suppression stems from a process termed visual marking, which suppresses irrelevant visual objects in anticipation of more relevant new objects ( Watson & Humphreys, 1997). The findings argue against alternative explanations such as the automatic capture by abrupt new onsets account.

Visual marking for search: behavioral and event-related potential analyses

Visual marking is an attentional mechanism of prioritizing the selection of new static or moving objects via top-down intentional inhibition of old objects [ Psychol. Rev. 104 (1997) 90–122]. The present study investigated the operation of visual marking using event-related brain potentials (ERPs). Participants searched a display for one of two target letters among randomly selected letter distractors. Two item set sizes were used in a two-stage display. Half of the items appeared for 1000 ms in the first stage followed by the remainder in the second stage. Three blocked conditions were used. In the Preview condition, targets appeared as one of a set of new items in Display 2. Items in Display 1 could thus be excluded from search by visual marking. In the Control condition, old items changed when new items appeared, and the target was equally likely to be at an old or a new position. In this condition marking is unlikely to be engaged since old locations could contain the target. In the Search condition, targets appeared either in Display 1 (80%) or Display 2 (20%), and Display 1 items did not change. The results showed condition-contingent attentional modulations in the N1/N2 range. In addition, a broadly distributed centrally-preponderant sustained negativity was obtained in the 350–750 ms time range after the onset of Display 1 for the Preview–Control comparison. This latter negativity is interpreted to reflect the processes involved in setting up and maintaining of visual marking. It demonstrated an effect of visual marking well prior to Display 2 onset, thereby ruling out an account of the preview benefit solely due to attentional capture by Display 2 item onset.

Inhibition of return in visual marking? The importance of the interstimulus interval and the type of search task

Four experiments are presented that examine the possibility that inhibition of return (IOR) may occur in visual marking. Previously, Watson and Humphreys (1997), using a cue duration of 750 ms and an interstimulus interval (ISI) of 250 ms, concluded that IOR was not present in visual marking. In the present study, the first experiment examined three ISIs (250 ms, 500 ms, and 750 ms) with a constant stimulus onset asynchrony (SOA, 1000 ms) in a typical cueing paradigm and failed to find IOR with the short ISI. Based on these findings, the second (feature search) and third (conjunction search) experiments tested for IOR by using a visual marking paradigm with a 500 ms ISI. Evidence for IOR was found in the feature search (preview condition similar to half-elements baseline condition) and not in the conjunction search (preview condition similar to the all-elements baseline). The typical preview effect was found in Experiment 4 with a cue duration 1000 ms and no ISI. Overall, these findings indicate that IOR may play a role in visual marking, but only with feature search tasks and long ISIs between displays.

Inter-response interference contributes to the sequencing deficit in frontal lobe lesions.

In this study we investigated the contribution of inter-response interference to the sequencing deficit in frontal lobe lesions. We examined inter-response interference in choice sequences through the reduction in inter-response interval produced by stimulus preview when compared with sequences performed without preview. If frontal lobe lesions result in a stronger inter-response interference, the facilitative effect of preview on inter-response interval should be attenuated. We compared nine patients with a frontal excision with nine patients with a temporal excision and nine controls in a task requiring rapid keypress responses to each of five letters in a sequence. In the no-preview condition, the five letters were presented one at a time, immediately following the previous response. In the preview condition, the five letters were presented simultaneously before the response sequence. Patients with a frontal lesion showed slower response times than the other groups. In normal subjects and patients with a temporal lesion, stimulus preview produced the expected reduction of inter-response time and the slowing of sequence initiation. In frontal lesions, however, preview did not reduce inter-response time and exacerbated the slowing of sequence initiation. The results indicate that patients with a frontal lobe lesion show increased interference between adjacent responses as well as a sequence initiation problem.

Effects of Job Previews on Self-Selection and Job Choice

Although the self-selection matching hypothesis is considered to be an integral part of the psychological effects of realistic job previews (RJPs), several writers have concluded that self-selection is not a valid explanation for the effect of RJPs on job survival (Colarelli, 1984; Reilly, Brown, Blood, & Malatesta, 1981). This conclusion, however, is based on research that has measured job acceptance rates as a surrogate measure for self-selection (Rynes, 1991; Wanous & Colella, 1989) and research that has often ignored the perception of choice boundary condition of RJPs (Breaugh, 1983). In the present study, a simulation of the job choice process was conducted in which 138 undergraduate commerce students were randomly assigned to either a one-job preview condition (an RJP or a traditional job preview, TJP) or a two-job preview condition (RJP and TJP) in order to examine the effects of job previews on self-selection and job choice. In addition, we also tested expectancy theory as a theoretical model to explain the effects of job previews on job choice. The relation between self-efficacy and job choice was also examined. As expected, differences in job acceptance rates were only found in the two-job preview condition in which most subjects (71.4%) selected the traditional job preview. Support was also found for the effect of job previews on self-selection and for expectancy theory as a model for the effects of job previews on job choice. Further, subjects with stronger self-efficacy beliefs were more likely to choose the RJP than the TJP, and self-efficacy significantly increased the accuracy of the expectancy theory model in predicting subjects′ job choice decision. Both the practical and research implications of the effects of job previews on self-selection and job choice are discussed.

Effects of optimistic versus realistic previews of training programs on self‐reported transfer of training

AbstractThe purpose of this study was to examine the impact of realistic versus optimistic previews of training programs on training transfer. Hicks and Klimoski (1987) suggested that a realistic training preview should increase trainee motivation by clarifying expectations and by matching training programs to individual needs. In contrast, this study predicted that an informative and optimistic training preview would not only help trainees see the relevance of the training program to their own jobs but also increase outcome expectations, self‐efficacy, motivation, learning, and transfer. When quantity of information was held constant across training preview conditions, the optimistic training preview had a more positive impact on outcome expectations, motivation, learning, reactions to training, and transfer than the realistic training preview.

Effects of Keying Method, Image Preview and Work/Rest Schedule on Posture of the Remote Bar Coding Operators

The main objectives of this study were to investigate the effects of different work/rest schedules, keying methods and preview conditions on postures preferred by the remote bar coding (RBC) operators, as well as on the patterns of postural changes over time, and to relate these to the perceived postural discomfort at work. Twelve operators (nine females and three males) were hired through a local employment service. A participation requirement was a minimum typing speed of 40 correct words per minute. Three factorial (2 × 2 × 3) design with replication was used. The experiment consisted of twelve scenarios utilizing three factors, i.e. 1) keying methodology (key all or key 5 digits only), 2) image preview (none or one), and 3) work/break schedule (50 minute/10 minute, 2 hour/15 minute, or flexible schedule). The data collection for biomechanical analysis of the RBC operators was performed using the video-recording technique. Assessment of the operator's postural discomfort was performed before the work started, immediately after each work period (during the break), and immediately after the task was completed. The results of postural discomfort analysis showed the significant effects of data collection time on all reported discomfort scores. The instruction to “key all” resulted in significantly higher wrist discomfort levels than the instruction “key 5 characters only.” The neck/head flexion was the lowest (mean = 30.2 degrees) for the flexible work/break schedule, and the highest (mean = 36.5 degrees) for the 50 minute work/10 minute break schedule. The preview condition resulted in smaller arm flexion (mean = 108.2 degrees) than the no preview condition (mean = 115.6 degrees). On average, the subjects used back support 34.7% of the time. When working with no image preview, the back rest was used 25% of the time. The back rest utilization increased for 50% of the time with the image preview, indicating more relaxed posture at work with the preview condition. The upper trunk angle (back inclination) assumed by the RBC operators was on average by 10 degrees greater than the angle preferred by the VDT operators.

The impact of task preview information as a function of recipient self-efficacy

Perceived general self-efficacy of a sample of 87 university students performing a job simulation task was hypothesized to moderate the relationship between task preview exposure and task performance and between task preview exposure and task self-efficacy. Two types of task previews (Favorable and Realistic) were used to test the proposed relationship. Using moderated regression analyses, significant General Self-Efficacy × Task Preview condition interaction effects were found for task performance. Task self-efficacy was significantly predicted by the levels of task preview condition. Implications for Realistic Job Preview research are discussed.

Lexical access during eye fixations in reading: Are word access codes used to integrate lexical information across interword fixations?

Eye fixation records during reading were obtained to test whether lexical access of a word is distributed across successive interword fixations. Specifically, prelexical analyses discerning the word access code could be performed during the parafoveal processing of a word and lexical access could be completed during the word's subsequent fixation. A series of sentences was read with each sentence containing either a 6-letter compound word (e.g., cowboy), a 6-letter pseudocompound word (e.g., carpet), or a 6-letter control word (e.g., mirror). Reading occurred under four parafoveal text preview conditions affording either no usable preview, preview of a word's beginning three letters, preview of a word's beginning four letters, or preview of a complete parafoveal word. Previews of three and four letters either corresponded to linguistically defined subword units (putative word access codes) or violated these units. The results showed that parafoveal preview benefits from 3- and 4-letter sequences were unaffected by the linguistic status of previewed letters, indicating that word access codes are not used to integrate lexical information across interword fixations. Parafoveal previews of whole words revealed, however, effects of linguistic status. Preview benefits were largest for pseudocompound words which comprised high frequency beginning and ending subword constituents and smallest for control words which did not contain subword constituents with lexical representations. These results support models of parafoveal word recognition which posit, first, that all letters of a parafoveal word contribute to the early phase of word identification and, second, that these letters form mutually reinforcing letter coalitions.

A study of the dynamic damper with a preview action. Experiment of the dynamic damper with a preview action.

This paper deals with a realization of a dynamic damper with a preview action already proposed by the authors. It is also the purpose of this paper to verify the control effect of the dynamic damper for the suppression of a transient vibration resulting from an impact force. First, this paper shows a mechanism of a newly designed dynamic damper with a preview action. Then, based upon three kinds of preview actions proposed in the previous papers, and impact experiment is carried out, verifying the effectiveness of these preview methods. Furthermore, an influence of the maximum impact force upon the control effect for the suppression of the first wave of the transient vibration is investigated. In addition, by varying preview conditions such as a preview time and an initial displacement of a damper mass, the control effect in terms of the preview action is considered.

Response programming, response production, and fractionated reaction time

A feature common to many studies investigating the relationship between reaction time (RT) and motor task demands is that, prior to responding, subjects have been able to preview the parameters of the movement they are required to make. This introduces the possibility of preprogramming the movement before entering the RT period, thus making it more difficult to detect a consistent relationship between RT and motor task demands. A “no-preview” condition (movement parameters concealed prior to the subject responding) was used in the present study to avoid this confusion. Reaction time was fractionated using surface EMG recording, and premotor RT (central component) was found to vary with motor task demands in a fashion supporting a study by Sheridan (1981). Movement velocity was implicated as a factor influencing programming difficulty, with low velocity movements appearing to present the greatest problem. A strong negative correlation was observed between premotor RT and average movement velocity. A “delay” condition was incorporated into the present study to consider the retention in memory of the programmed information. Briefly, the pattern of results for the delay condition fell between the no-preview and preview conditions. The implications of these findings are discussed.

Color Balance and Density of Films for Tungsten (Theatrical) and Arc (TV Preview) Projection

Contrary to expectations, it was found that there was not a significant difference in the preferred color balance of prints selected from a large range of color balances viewed in a darkened room with tungsten (3600-K) projection or in a TV preview room (5400-K with lighted surround). All prints ranked good or excellent in the TV preview room were given a similar ranking in the theatrical projection room. The converse was not true — some prints accepted under the less critical darkened-room viewing were not acceptable under TV preview conditions. The same print density, also, is preferred under both viewing conditions. The conclusion is drawn that only one print balance, that selected under the more rigorous TV preview-room conditions, is needed for both theatrical and TV use.

EXTRA-OCULAR FEEDBACK IN BINOCULAR RIVALRY.

Current theorizing has led to the proposal that feedback from contour scanning eye nlovements plays a role in the visibility of the contour scanned. It is assumed that a central mechanism establishes match or mismatch relations between the pattern of stimulation fed back from the extra-ocular muscles and the many patterns of stimulation that may arise from scanning one contour in a field of many. The particular retinal stimulations that match extra-ocular feedback are enhanced in visibility. Thus, in regard to binocular rivalry, rhe expectation is that the stimulus seen on initial viewing will be the one that matches contemporaneous extra-ocular feedback. To test this expectation, binocular rivalry was induced by having S view stereoscopically the red vertical and green horizontal members of a cross. In two previewing conditions, S scanned for 30 sec. with eyes closed. In one condition S scanned vertically and in the other condition, S scanned horizontally. Thus, when S opens his eyes to view the two stimuli, preview conditions have provided, it is assumed, aftereffects of feedback from scanning. These aftereffects provide the hypothesized match with one of the two stimuli presented, viz., vertical preview with vertical stimulus and horizontal preview with horizontal stimulus. All Ss were practiced in reporting by telegraph key the duration that one stimulus was seen alone or in front of the other stimulus. Ss were tested twice for each preview condition. A Latin square design controlled for sequence of conditions within two double fatigue orders.