{"id":"https://openalex.org/W7161188972","doi":"https://doi.org/10.48550/arxiv.2605.12549","title":"What Happens Before Decoding? Prefill Determines GUI Grounding in VLMs","display_name":"What Happens Before Decoding? Prefill Determines GUI Grounding in VLMs","publication_year":2026,"publication_date":"2026-05-10","ids":{"openalex":"https://openalex.org/W7161188972","doi":"https://doi.org/10.48550/arxiv.2605.12549"},"language":null,"primary_location":{"id":"doi:10.48550/arxiv.2605.12549","is_oa":true,"landing_page_url":"https://doi.org/10.48550/arxiv.2605.12549","pdf_url":null,"source":{"id":"https://openalex.org/S4306400194","display_name":"arXiv (Cornell University)","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I205783295","host_organization_name":"Cornell University","host_organization_lineage":["https://openalex.org/I205783295"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":null,"is_accepted":false,"is_published":false,"raw_source_name":null,"raw_type":"Preprint"},"type":"preprint","indexed_in":["datacite"],"open_access":{"is_oa":true,"oa_status":"green","oa_url":"https://doi.org/10.48550/arxiv.2605.12549","any_repository_has_fulltext":true},"authorships":[{"author_position":"first","author":{"id":"https://openalex.org/A5101436310","display_name":"Jiaping Lin","orcid":"https://orcid.org/0000-0002-4363-1801"},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Lin, Jiaping","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5136166883","display_name":"Fei Shen","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Shen, Fei","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5136158203","display_name":"Junzhe Li","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Li, Junzhe","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5136171803","display_name":"Ping Nie","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Nie, Ping","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5136094208","display_name":"Fei YU","orcid":"https://orcid.org/0000-0002-7857-4827"},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Yu, Fei","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5136099230","display_name":"Ming Li","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Li, Ming","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"last","author":{"id":"https://openalex.org/A5136103834","display_name":"Haizhou Li","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Li, Haizhou","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]}],"institutions":[],"countries_distinct_count":0,"institutions_distinct_count":0,"corresponding_author_ids":[],"corresponding_institution_ids":[],"apc_list":null,"apc_paid":null,"fwci":null,"has_fulltext":false,"cited_by_count":0,"citation_normalized_percentile":null,"cited_by_percentile_year":null,"biblio":{"volume":null,"issue":null,"first_page":null,"last_page":null},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T11714","display_name":"Multimodal Machine Learning Applications","score":0.8959000110626221,"subfield":{"id":"https://openalex.org/subfields/1707","display_name":"Computer Vision and Pattern Recognition"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},"topics":[{"id":"https://openalex.org/T11714","display_name":"Multimodal Machine Learning Applications","score":0.8959000110626221,"subfield":{"id":"https://openalex.org/subfields/1707","display_name":"Computer Vision and Pattern Recognition"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T11307","display_name":"Domain Adaptation and Few-Shot Learning","score":0.028300000354647636,"subfield":{"id":"https://openalex.org/subfields/1702","display_name":"Artificial Intelligence"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T10036","display_name":"Advanced Neural Network Applications","score":0.01810000091791153,"subfield":{"id":"https://openalex.org/subfields/1707","display_name":"Computer Vision and Pattern Recognition"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}}],"keywords":[{"id":"https://openalex.org/keywords/inference","display_name":"Inference","score":0.6190999746322632},{"id":"https://openalex.org/keywords/selection","display_name":"Selection (genetic algorithm)","score":0.5342000126838684},{"id":"https://openalex.org/keywords/ground","display_name":"Ground","score":0.5170000195503235},{"id":"https://openalex.org/keywords/decoding-methods","display_name":"Decoding methods","score":0.4424000084400177},{"id":"https://openalex.org/keywords/code","display_name":"Code (set theory)","score":0.42649999260902405},{"id":"https://openalex.org/keywords/visualization","display_name":"Visualization","score":0.3668000102043152},{"id":"https://openalex.org/keywords/scheme","display_name":"Scheme (mathematics)","score":0.34619998931884766},{"id":"https://openalex.org/keywords/source-code","display_name":"Source code","score":0.33309999108314514}],"concepts":[{"id":"https://openalex.org/C41008148","wikidata":"https://www.wikidata.org/wiki/Q21198","display_name":"Computer science","level":0,"score":0.7563999891281128},{"id":"https://openalex.org/C2776214188","wikidata":"https://www.wikidata.org/wiki/Q408386","display_name":"Inference","level":2,"score":0.6190999746322632},{"id":"https://openalex.org/C81917197","wikidata":"https://www.wikidata.org/wiki/Q628760","display_name":"Selection (genetic algorithm)","level":2,"score":0.5342000126838684},{"id":"https://openalex.org/C168993435","wikidata":"https://www.wikidata.org/wiki/Q6501125","display_name":"Ground","level":2,"score":0.5170000195503235},{"id":"https://openalex.org/C154945302","wikidata":"https://www.wikidata.org/wiki/Q11660","display_name":"Artificial intelligence","level":1,"score":0.5098000168800354},{"id":"https://openalex.org/C57273362","wikidata":"https://www.wikidata.org/wiki/Q576722","display_name":"Decoding methods","level":2,"score":0.4424000084400177},{"id":"https://openalex.org/C2776760102","wikidata":"https://www.wikidata.org/wiki/Q5139990","display_name":"Code (set theory)","level":3,"score":0.42649999260902405},{"id":"https://openalex.org/C36464697","wikidata":"https://www.wikidata.org/wiki/Q451553","display_name":"Visualization","level":2,"score":0.3668000102043152},{"id":"https://openalex.org/C77618280","wikidata":"https://www.wikidata.org/wiki/Q1155772","display_name":"Scheme (mathematics)","level":2,"score":0.34619998931884766},{"id":"https://openalex.org/C43126263","wikidata":"https://www.wikidata.org/wiki/Q128751","display_name":"Source code","level":2,"score":0.33309999108314514},{"id":"https://openalex.org/C119857082","wikidata":"https://www.wikidata.org/wiki/Q2539","display_name":"Machine learning","level":1,"score":0.3264999985694885},{"id":"https://openalex.org/C31972630","wikidata":"https://www.wikidata.org/wiki/Q844240","display_name":"Computer vision","level":1,"score":0.3163999915122986},{"id":"https://openalex.org/C2780451532","wikidata":"https://www.wikidata.org/wiki/Q759676","display_name":"Task (project management)","level":2,"score":0.30730000138282776},{"id":"https://openalex.org/C2776401178","wikidata":"https://www.wikidata.org/wiki/Q12050496","display_name":"Feature (linguistics)","level":2,"score":0.30720001459121704},{"id":"https://openalex.org/C125411270","wikidata":"https://www.wikidata.org/wiki/Q18653","display_name":"Encoding (memory)","level":2,"score":0.28859999775886536},{"id":"https://openalex.org/C2777055276","wikidata":"https://www.wikidata.org/wiki/Q7936580","display_name":"Visual approach","level":2,"score":0.2847000062465668},{"id":"https://openalex.org/C204321447","wikidata":"https://www.wikidata.org/wiki/Q30642","display_name":"Natural language processing","level":1,"score":0.28279998898506165},{"id":"https://openalex.org/C2777508537","wikidata":"https://www.wikidata.org/wiki/Q7936620","display_name":"Visual reasoning","level":2,"score":0.2818000018596649},{"id":"https://openalex.org/C26517878","wikidata":"https://www.wikidata.org/wiki/Q228039","display_name":"Key (lock)","level":2,"score":0.26089999079704285},{"id":"https://openalex.org/C44291984","wikidata":"https://www.wikidata.org/wiki/Q1074173","display_name":"Question answering","level":2,"score":0.257099986076355},{"id":"https://openalex.org/C137293760","wikidata":"https://www.wikidata.org/wiki/Q3621696","display_name":"Language model","level":2,"score":0.25540000200271606},{"id":"https://openalex.org/C199360897","wikidata":"https://www.wikidata.org/wiki/Q9143","display_name":"Programming language","level":1,"score":0.25519999861717224},{"id":"https://openalex.org/C107457646","wikidata":"https://www.wikidata.org/wiki/Q207434","display_name":"Human\u2013computer interaction","level":1,"score":0.25360000133514404}],"mesh":[],"locations_count":1,"locations":[{"id":"doi:10.48550/arxiv.2605.12549","is_oa":true,"landing_page_url":"https://doi.org/10.48550/arxiv.2605.12549","pdf_url":null,"source":{"id":"https://openalex.org/S4306400194","display_name":"arXiv (Cornell University)","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I205783295","host_organization_name":"Cornell University","host_organization_lineage":["https://openalex.org/I205783295"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":null,"is_accepted":false,"is_published":null,"raw_source_name":null,"raw_type":"Preprint"}],"best_oa_location":{"id":"doi:10.48550/arxiv.2605.12549","is_oa":true,"landing_page_url":"https://doi.org/10.48550/arxiv.2605.12549","pdf_url":null,"source":{"id":"https://openalex.org/S4306400194","display_name":"arXiv (Cornell University)","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I205783295","host_organization_name":"Cornell University","host_organization_lineage":["https://openalex.org/I205783295"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":null,"is_accepted":false,"is_published":false,"raw_source_name":null,"raw_type":"Preprint"},"sustainable_development_goals":[{"id":"https://metadata.un.org/sdg/16","display_name":"Peace, Justice and strong institutions","score":0.5202977061271667}],"awards":[],"funders":[],"has_content":{"grobid_xml":false,"pdf":false},"content_urls":null,"referenced_works_count":0,"referenced_works":[],"related_works":[],"abstract_inverted_index":{"Existing":[0],"training-free":[1,118],"approaches":[2],"for":[3],"GUI":[4,55],"grounding":[5,56,70],"often":[6],"rely":[7],"on":[8,111,207],"multiple":[9],"inference":[10,122],"runs,":[11],"such":[12],"as":[13,95,99,154],"iterative":[14],"cropping":[15],"or":[16],"candidate":[17,79,102],"aggregation,":[18],"to":[19,130,161,173,205],"identify":[20,62],"target":[21,132,157],"elements.":[22],"Despite":[23],"this":[24,48,112],"additional":[25,199],"computation,":[26],"each":[27],"forward":[28],"pass":[29],"still":[30],"independently":[31],"interprets":[32],"the":[33,37,75,83,88,96,143,147,162,166,171],"instruction":[34,167],"and":[35,61,159,185,193],"parses":[36],"visual":[38,45,135],"layout,":[39],"without":[40,198],"enabling":[41,170],"progressive":[42],"interaction":[43],"among":[44],"tokens.":[46],"In":[47],"paper,":[49],"we":[50,114],"study":[51],"what":[52],"happens":[53],"during":[54,108],"in":[57,101],"Vision-Language":[58],"Models":[59],"(VLMs)":[60],"a":[63,72,117,155],"previously":[64],"overlooked":[65],"bottleneck.":[66],"We":[67],"show":[68],"that":[69,120,137],"follows":[71],"two-stage":[73],"paradigm:":[74],"prefill":[76,94,128],"stage":[77,85,129],"determines":[78],"UI":[80],"elements,":[81],"while":[82],"decoding":[84],"subsequently":[86],"refines":[87],"final":[89,148],"coordinates.":[90],"This":[91],"asymmetry":[92],"establishes":[93],"critical":[97],"step,":[98],"errors":[100],"selection":[103],"cannot":[104],"be":[105,211],"effectively":[106],"corrected":[107],"decoding.":[109],"Based":[110],"observation,":[113],"propose":[115],"Re-Prefill,":[116],"method":[119],"revisits":[121],"by":[123],"introducing":[124],"an":[125],"attention-guided":[126],"second":[127],"refine":[131],"selection.":[133],"Specifically,":[134],"tokens":[136],"consistently":[138],"receive":[139],"high":[140],"attention":[141],"from":[142],"query":[144],"position,":[145],"i.e.,":[146],"token,":[149],"across":[150,182],"layers":[151],"are":[152],"extracted":[153],"preliminary":[156],"hypothesis":[158],"appended":[160],"input,":[163],"together":[164],"with":[165,201],"hidden":[168],"states,":[169],"model":[172],"deeply":[174],"re-think":[175],"its":[176],"decision":[177],"before":[178],"coordinate":[179],"generation.":[180],"Experiments":[181],"four":[183],"VLMs":[184],"five":[186],"benchmarks,":[187],"including":[188],"ScreenSpot-Pro,":[189],"ScreenSpot-V2,":[190],"OSWorld-G,":[191],"UI-Vision,":[192],"MMBench-GUI,":[194],"demonstrate":[195],"consistent":[196],"improvements":[197],"training,":[200],"gains":[202],"of":[203],"up":[204],"4.3%":[206],"ScreenSpot-Pro.":[208],"Code":[209],"will":[210],"available":[212],"at":[213],"https://github.com/linjiaping1/Re-Prefill.":[214]},"counts_by_year":[],"updated_date":"2026-07-01T06:00:48.157686","created_date":"2026-05-15T00:00:00"}
