{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/101245"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/101245","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Systematic variability in stage-one processing as revealed by eye movements in efficient visual search","abstract":"Most models of visual search have reported that efficient search tasks are characterized by “flat” search slopes of less than 10ms/item. Based on this, such models have concluded that stage-one processing times are invariant. In contrast, our lab recently reported systematic variability in stage-one processing times. In an efficient search task with a fixed target, reaction times were observed to increase logarithmically with set size. In addition, this logarithmic increase was modulated by the visual similarity between the target and the lures. We thus proposed a new model of visual search: stage-one processing is characterized by a parallel, capacity-unlimited evidence accumulation process that is affected by both lure-target similarity (due to resolution limits of the eye) as well as the number of items on the display (due to the exhaustive nature of evidence accumulation). Here, we examined eye movements to further elaborate on these novel contributions of our model. When lure-target similarity was high, participants made more fixations, had longer initial saccade latencies, and were more likely to make an initial saccade that is target-uninformed. Effects of set size were also observed on some of these variables. Interestingly, these eye movement results are incompatible with our model’s proposal of a completely exhaustive stage-one process. To reconcile these differences, we update our model to propose that (1) top-down control factors such as strategy and task instructions influence the time to stop evidence accumulation in stage one and (2) exhaustive processing occurs at a smaller spatial scale (i.e. not necessarily across the entire display) although all locations are accumulating evidence.","abstract_html":"Most models of visual search have reported that efficient search tasks are characterized by “flat” search slopes of less than 10ms/item. Based on this, such models have concluded that stage-one processing times are invariant. In contrast, our lab recently reported systematic variability in stage-one processing times. In an efficient search task with a fixed target, reaction times were observed to increase logarithmically with set size. In addition, this logarithmic increase was modulated by the visual similarity between the target and the lures. We thus proposed a new model of visual search: stage-one processing is characterized by a parallel, capacity-unlimited evidence accumulation process that is affected by both lure-target similarity (due to resolution limits of the eye) as well as the number of items on the display (due to the exhaustive nature of evidence accumulation). Here, we examined eye movements to further elaborate on these novel contributions of our model. When lure-target similarity was high, participants made more fixations, had longer initial saccade latencies, and were more likely to make an initial saccade that is target-uninformed. Effects of set size were also observed on some of these variables. Interestingly, these eye movement results are incompatible with our model’s proposal of a completely exhaustive stage-one process. To reconcile these differences, we update our model to propose that (1) top-down control factors such as strategy and task instructions influence the time to stop evidence accumulation in stage one and (2) exhaustive processing occurs at a smaller spatial scale (i.e. not necessarily across the entire display) although all locations are accumulating evidence.","abstract_has_math":false,"creators":["Ng, Gavin Jun Peng"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Psychology","degree_department":null,"school":null,"contributors":["Lleras, Alejandro","Buetti, Simona"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018-09-04T20:42:02Z","date_published":"2018-09-04T20:42:02Z","updated_at":"2026-07-22T22:24:38Z","subjects":["visual search","efficient search","eye movements"],"languages":["en"],"rights":["Copyright 2018 Gavin Ng"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/101245","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Lleras, Alejandro","Buetti, Simona"]},{"key":"dc:creator","label":"Author","values":["Ng, Gavin Jun Peng"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-09-04T20:42:02Z","2020-09-05T09:15:09Z","2018-04-27","2018-05"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Psychology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["visual search","efficient search","eye movements"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2018 Gavin Ng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/101245"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Most models of visual search have reported that efficient search tasks are characterized by “flat” search slopes of less than 10ms/item. Based on this, such models have concluded that stage-one processing times are invariant. In contrast, our lab recently reported systematic variability in stage-one processing times. In an efficient search task with a fixed target, reaction times were observed to increase logarithmically with set size. In addition, this logarithmic increase was modulated by the visual similarity between the target and the lures. We thus proposed a new model of visual search: stage-one processing is characterized by a parallel, capacity-unlimited evidence accumulation process that is affected by both lure-target similarity (due to resolution limits of the eye) as well as the number of items on the display (due to the exhaustive nature of evidence accumulation). Here, we examined eye movements to further elaborate on these novel contributions of our model. When lure-target similarity was high, participants made more fixations, had longer initial saccade latencies, and were more likely to make an initial saccade that is target-uninformed. Effects of set size were also observed on some of these variables. Interestingly, these eye movement results are incompatible with our model’s proposal of a completely exhaustive stage-one process. To reconcile these differences, we update our model to propose that (1) top-down control factors such as strategy and task instructions influence the time to stop evidence accumulation in stage one and (2) exhaustive processing occurs at a smaller spatial scale (i.e. not necessarily across the entire display) although all locations are accumulating evidence.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2020-05-01","The student, Gavin Ng, accepted the attached license on 2018-04-27 at 13:53.","The student, Gavin Ng, submitted this Thesis for approval on 2018-04-27 at 14:29.","This Thesis was approved for publication on 2018-04-27 at 16:02.","DSpace SAF Submission Ingestion Package generated from Vireo submission #12542 on 2018-08-31 at 17:21:51","Made available in DSpace on 2018-09-04T20:42:02Z (GMT). No. of bitstreams: 2 NG-THESIS-2018.pdf: 667301 bytes, checksum: 0270bf410766575e4c949844dc1d8992 (MD5) LICENSE.txt: 4205 bytes, checksum: 75c1798559fb566cb0565bb43ac4bbe3 (MD5) Previous issue date: 2018-04-27","Embargo set by: Seth Robbins for item 107330 Lift date: 2020-09-04T20:42:08Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 107330 on 2020-09-05T09:15:09Z."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Systematic variability in stage-one processing as revealed by eye movements in efficient visual search"]}]}],"canonical_facts":{"dc:contributor":["Lleras, Alejandro","Buetti, Simona"],"dc:creator":["Ng, Gavin Jun Peng"],"dc:date":["2018-09-04T20:42:02Z","2020-09-05T09:15:09Z","2018-04-27","2018-05"],"dc:description":["Most models of visual search have reported that efficient search tasks are characterized by “flat” search slopes of less than 10ms/item. Based on this, such models have concluded that stage-one processing times are invariant. In contrast, our lab recently reported systematic variability in stage-one processing times. In an efficient search task with a fixed target, reaction times were observed to increase logarithmically with set size. In addition, this logarithmic increase was modulated by the visual similarity between the target and the lures. We thus proposed a new model of visual search: stage-one processing is characterized by a parallel, capacity-unlimited evidence accumulation process that is affected by both lure-target similarity (due to resolution limits of the eye) as well as the number of items on the display (due to the exhaustive nature of evidence accumulation). Here, we examined eye movements to further elaborate on these novel contributions of our model. When lure-target similarity was high, participants made more fixations, had longer initial saccade latencies, and were more likely to make an initial saccade that is target-uninformed. Effects of set size were also observed on some of these variables. Interestingly, these eye movement results are incompatible with our model’s proposal of a completely exhaustive stage-one process. To reconcile these differences, we update our model to propose that (1) top-down control factors such as strategy and task instructions influence the time to stop evidence accumulation in stage one and (2) exhaustive processing occurs at a smaller spatial scale (i.e. not necessarily across the entire display) although all locations are accumulating evidence.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2020-05-01","The student, Gavin Ng, accepted the attached license on 2018-04-27 at 13:53.","The student, Gavin Ng, submitted this Thesis for approval on 2018-04-27 at 14:29.","This Thesis was approved for publication on 2018-04-27 at 16:02.","DSpace SAF Submission Ingestion Package generated from Vireo submission #12542 on 2018-08-31 at 17:21:51","Made available in DSpace on 2018-09-04T20:42:02Z (GMT). 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