Diane E. Williams

Preattentive guidance of eye movements during triple conjunction search tasks: the effects of feature discriminability and saccadic amplitude.

Eye movements were monitored during the performance of triple conjunction search tasks. Stimuli varied in color, shape, and orientation. Across trials, the target was either present or absent, and displays consisted of 6, 12, or 24 stimuli. Stimulus discriminability was manipulated for the shape dimension, with half of the participants seeing displays of Es and Fs (low-discriminability [LD] condition) and half seeing displays of Cs and Ts (high-discriminability [HD] condition). Participants in both conditions performed two search tasks. In the single-feature (SF) task, the target stimulus shared one feature with each of the distractors, whereas in the two-feature (TF) task, it shared two features with each distractor. An examination of saccadic endpoints revealed that participants were more likely to fixate on distractor stimuli sharing color (SF task) or color and shape (TF task) with the target. This was a robust finding, being observed across participants, saccades of different amplitudes and sequential position, and following short and long latencies to move. The extent to which participants made use of shape information increased with discriminability.

Saccadic Selectivity During Visual Search: The Influence of Central Processing Difficulty

Publisher Summary This chapter examines the robustness of guidance of eye movements during visual search. Visual search is one of the dominant paradigms used for investigating visual attention. In a typical visual search task, participants have to decide whether a search display contains a designated target among distractors (nontarget elements). Consistent with major visual search theories, experiments discussed in the chapter demonstrate that participants direct their saccades selectively during the search process, revealing a strong correspondence between target-distractor similarity and saccadic frequency toward the respective distractors. While the duration of current fixations increased with increasing target-distractor similarity, there was no evidence that saccadic selectivity was influenced by the target-distractor similarity of the previously fixated display item or the duration of the previous fixation. These findings are inconsistent with the predictions by the waiting-room model. The chapter manipulates the difficulty of the central discrimination by introducing a concurrent visual task and presenting a gaze-contingent moving foveal mask. Although manipulations substantially degraded the overall visual search performance, the magnitude of peripheral selection was not affected. This is not consistent with the notion that the central discrimination and the peripheral analysis share the same pool of attentional resources as suggested by the foveal load model. Thus, these experiments provide convergent evidence that peripheral selection is a robust process, largely independent of the central processing difficulty.

Decision making in palliative radiation therapy: reframing hope in caregivers and patients with brain metastases

Goals of workTo explore the major factors important in decision making for whole-brain radiotherapy (WBRT) for patients with brain metastases and their caregivers.Patients and methodsTwo parallel qualitative studies, one for patients and one for caregivers of patients with newly diagnosed brain metastases, were conducted. Semistructured interviews were conducted and audiotaped with each participant. Content analysis and theme extraction of the transcripts were undertaken to identify recurring themes and relational patterns.ResultsTwenty patients and 19 caregivers (including eight patient and caregiver pairs) were recruited into the study. Four major factors were identified to influence decision making of whole-brain radiation: hope, knowledge, expectations of radiation therapy, and current symptoms. Analysis reveals that patients generally focus on current informational needs, while caregivers want more information about the future (e.g., life expectancy and anticipated symptoms). Caregivers expressed frustration when unable to explore future needs because patients were unprepared to discuss prognostic issues. Participants expressed substantial relief when offered WBRT after the diagnosis, but WBRT is often considered the only available plan rather than an informed choice.ConclusionsGiven the importance of caregivers in the care of patients with brain metastases, fulfilling their unique informational needs appears to require more attention. The blurred boundary between hopes and expectations for WBRT creates unique challenges in joint treatment decision making for patients with brain metastases and their caregivers.

Saccadic Selectivity During Visual Search

Publisher Summary This chapter examines the robustness of guidance of eye movements during visual search. Visual search is one of the dominant paradigms used for investigating visual attention. In a typical visual search task, participants have to decide whether a search display contains a designated target among distractors (nontarget elements). Consistent with major visual search theories, experiments discussed in the chapter demonstrate that participants direct their saccades selectively during the search process, revealing a strong correspondence between target-distractor similarity and saccadic frequency toward the respective distractors. While the duration of current fixations increased with increasing target-distractor similarity, there was no evidence that saccadic selectivity was influenced by the target-distractor similarity of the previously fixated display item or the duration of the previous fixation. These findings are inconsistent with the predictions by the waiting-room model. The chapter manipulates the difficulty of the central discrimination by introducing a concurrent visual task and presenting a gaze-contingent moving foveal mask. Although manipulations substantially degraded the overall visual search performance, the magnitude of peripheral selection was not affected. This is not consistent with the notion that the central discrimination and the peripheral analysis share the same pool of attentional resources as suggested by the foveal load model. Thus, these experiments provide convergent evidence that peripheral selection is a robust process, largely independent of the central processing difficulty.

Chapter 4 – Saccadic Selectivity During Visual Search: The Influence of Central Processing Difficulty

Publisher Summary This chapter examines the robustness of guidance of eye movements during visual search. Visual search is one of the dominant paradigms used for investigating visual attention. In a typical visual search task, participants have to decide whether a search display contains a designated target among distractors (nontarget elements). Consistent with major visual search theories, experiments discussed in the chapter demonstrate that participants direct their saccades selectively during the search process, revealing a strong correspondence between target-distractor similarity and saccadic frequency toward the respective distractors. While the duration of current fixations increased with increasing target-distractor similarity, there was no evidence that saccadic selectivity was influenced by the target-distractor similarity of the previously fixated display item or the duration of the previous fixation. These findings are inconsistent with the predictions by the waiting-room model. The chapter manipulates the difficulty of the central discrimination by introducing a concurrent visual task and presenting a gaze-contingent moving foveal mask. Although manipulations substantially degraded the overall visual search performance, the magnitude of peripheral selection was not affected. This is not consistent with the notion that the central discrimination and the peripheral analysis share the same pool of attentional resources as suggested by the foveal load model. Thus, these experiments provide convergent evidence that peripheral selection is a robust process, largely independent of the central processing difficulty.