Driving and visuospatial performance in people with hemianopia

Practical fitness to drive was studied in 28 patients with homonymous hemianopia (HH). More specifically, visual performance during driving and neuropsychological visuospatial test performance were compared and related. Visuospatial tests were a priori classified in four visuospatial sets, and were...

Full description

Saved in:
Bibliographic Details
Published in:Neuropsychological rehabilitation Vol. 12; no. 5; pp. 419 - 437
Main Authors: Tant, M.L.M., Brouwer, W.H., Cornelissen, F.W., Kooijman, A.C.
Format: Journal Article
Language:English
Published: Hove Taylor & Francis Group 01-12-2002
Taylor & Francis
Psychology Press
Subjects:
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Abstract Practical fitness to drive was studied in 28 patients with homonymous hemianopia (HH). More specifically, visual performance during driving and neuropsychological visuospatial test performance were compared and related. Visuospatial tests were a priori classified in four visuospatial sets, and were evaluated on three measures, namely lateralisation, speed, and accuracy. Driving safety and fluency was assessed by means of a practical test-ride and scored using a structured protocol. It was concluded that HH cannot be considered a definite contraindication for holding a drivers' licence since not all patients failed the testride. The most frequent remark made by the driving expert was a lack of stability in steering. It was found that visual performance during driving was significantly related to visuospatial test performance, operationally defined as a function of typical visual HH disability. A specific combination of the lateralisation, speed and accuracy measures of the visuospatial sets explained 77% of the variance in visual performance during driving. For deciding which type of mobility rehabilitation goal is feasible in HH, our results suggested administering the Grey Scales task, the Trailmaking test, the Bells test and a Hidden Figures test.
AbstractList Practical fitness to drive was studied in 28 patients with homonymous hemianopia (HH). More specifically, visual performance during driving and neuropsychological visuospatial test performance were compared and related. Visuospatial tests were a priori classified in four visuospatial sets, and were evaluated on three measures, namely lateralisation, speed, and accuracy. Driving safety and fluency was assessed by means of a practical test-ride and scored using a structured protocol. It was concluded that HH cannot be considered a definite contraindication for holding a drivers' licence since not all patients failed the testride. The most frequent remark made by the driving expert was a lack of stability in steering. It was found that visual performance during driving was significantly related to visuospatial test performance, operationally defined as a function of typical visual HH disability. A specific combination of the lateralisation, speed and accuracy measures of the visuospatial sets explained 77% of the variance in visual performance during driving. For deciding which type of mobility rehabilitation goal is feasible in HH, our results suggested administering the Grey Scales task, the Trailmaking test, the Bells test and a Hidden Figures test.
Practical fitness to drive was studied in 28 patients with homonymous hemianopia (HH). More specifically, visual performance during driving and neuropsychological visuospatial test performance were compared and related. Visuospatial tests were a priori classified in four visuospatial sets, and were evaluated on three measures, namely lateralisation, speed, and accuracy. Driving safety and fluency was assessed by means of a practical test-ride and scored using a structured protocol. It was concluded that HH cannot be considered a definite contraindication for holding a drivers' licence since not all patients failed the test-ride. The most frequent remark made by the driving expert was a lack of stability in steering. It was found that visual performance during driving was significantly related to visuospatial test performance, operationally defined as a function of typical visual HH disability. A specific combination of the lateralisation, speed and accuracy measures of the visuospatial sets explained 77% of the variance in visual performance during driving. For deciding which type of mobility rehabilitation goal is feasible in HH, our results suggested administering the Grey Scales task, the Trailmaking test, the Bells test and a Hidden Figures test. (Original abstract)
Author Cornelissen, F.W.
Tant, M.L.M.
Brouwer, W.H.
Kooijman, A.C.
Author_xml – sequence: 1
  givenname: M.L.M.
  surname: Tant
  fullname: Tant, M.L.M.
– sequence: 2
  givenname: W.H.
  surname: Brouwer
  fullname: Brouwer, W.H.
– sequence: 3
  givenname: F.W.
  surname: Cornelissen
  fullname: Cornelissen, F.W.
– sequence: 4
  givenname: A.C.
  surname: Kooijman
  fullname: Kooijman, A.C.
BackLink http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=14398956$$DView record in Pascal Francis
BookMark eNqFkF1LwzAUhoNMcJv-AO96o3fVk4-mKYgg8xMG3uw-pG3iIl1Sk25z_97OTbwY4lU45HleznlHaOC80widY7jCIOAaCg4EMBDGAAALeoSGmHGWAi_YAA23_2kP4BM0ivF9iwDjQ3R7H-zKurdEuTpZ2bj0sVWdVU3S6mB8WChX6cS6fvRto5O17ebJXC-scr616hQdG9VEfbZ_x2j2-DCbPKfT16eXyd00rRgTXUo5MdQIXLOyzhWnkAtjMtIPZQFKC1rWFQPMc6hqwjGpDQWTs9KouiQFoWN0uYttg_9Y6tjJhY2VbhrltF9GmeWYZEzQHsQ7sAo-xqCNbINdqLCRGOS2KHlQVO9c7MNVrFRjQn-yjb8io4UoMt5z-Y6z7ruYtQ9NLTu1aXz4kQ7SZffZ9ebNvyb9e8EvaoiO3Q
CitedBy_id crossref_primary_10_1016_j_ncl_2015_08_009
crossref_primary_10_1016_j_visres_2011_10_019
crossref_primary_10_1111_cxo_12425
crossref_primary_10_3389_fnhum_2022_938140
crossref_primary_10_1155_2012_176806
crossref_primary_10_1080_15389588_2015_1038786
crossref_primary_10_1371_journal_pone_0056615
crossref_primary_10_1097_WAD_0000000000000221
crossref_primary_10_1016_j_cortex_2015_05_010
crossref_primary_10_1016_j_survophthal_2013_02_006
crossref_primary_10_3233_JAD_181095
crossref_primary_10_1111_cxo_12391
crossref_primary_10_1097_OPX_0000000000001421
crossref_primary_10_22599_bioj_129
crossref_primary_10_1080_13882350390486965
crossref_primary_10_5014_ajot_2019_030973
crossref_primary_10_1146_annurev_vision_100820_085030
crossref_primary_10_1177_0308022614562786
crossref_primary_10_1016_j_visres_2012_06_004
crossref_primary_10_1371_journal_pone_0299129
crossref_primary_10_1016_j_neuropsychologia_2003_07_007
crossref_primary_10_1080_15389588_2016_1232809
crossref_primary_10_3109_02713683_2010_548893
crossref_primary_10_1002_gps_5854
crossref_primary_10_2182_cjot_2011_78_2_3
crossref_primary_10_1007_s00415_014_7554_x
crossref_primary_10_1371_journal_pone_0149566
crossref_primary_10_1080_02703181_2021_1873476
crossref_primary_10_1111_j_1442_9071_2007_01544_x
crossref_primary_10_1016_j_cortex_2019_09_008
crossref_primary_10_1111_j_1755_3768_2011_02315_x
crossref_primary_10_1371_journal_pone_0087470
crossref_primary_10_5014_ajot_64_2_268
Cites_doi 10.1212/WNL.30.5.509
10.1097/00002060-199903000-00010
10.1080/01688638908400936
10.1016/S0028-3932(98)00074-8
10.1080/09602019108520162
10.3109/02699059409150996
10.1016/S0042-6989(02)00044-5
10.1136/jnnp.51.12.1481
10.1016/S0028-3932(01)00197-X
10.1037/0894-4105.4.2.87
10.1177/001872089103300503
10.1097/00006324-199312000-00007
10.1076/vimr.1.1.23.4450
10.1007/s001150050355
10.1016/S0039-6257(99)00035-1
10.1093/brain/105.2.301
10.1080/J148v03n02_05
ContentType Journal Article
Copyright Copyright Taylor & Francis Group, LLC 2002
2003 INIST-CNRS
Copyright_xml – notice: Copyright Taylor & Francis Group, LLC 2002
– notice: 2003 INIST-CNRS
DBID IQODW
AAYXX
CITATION
7QJ
DOI 10.1080/09602010244000183
DatabaseName Pascal-Francis
CrossRef
Applied Social Sciences Index & Abstracts (ASSIA)
DatabaseTitle CrossRef
Applied Social Sciences Index and Abstracts (ASSIA)
DatabaseTitleList
Applied Social Sciences Index and Abstracts (ASSIA)
DeliveryMethod fulltext_linktorsrc
Discipline Medicine
EISSN 1464-0694
EndPage 437
ExternalDocumentID 10_1080_09602010244000183
14398956
10098935
Genre Original Articles
GroupedDBID ---
.7I
.GJ
.QK
0BK
0R~
123
29N
2QV
36B
4.4
53G
5VS
AAAVI
AAGZJ
AAMFJ
AAMIU
AAPUL
AATTQ
AAWTL
AAZMC
ABBKH
ABCCY
ABDBF
ABFIM
ABIVO
ABJVF
ABLIJ
ABPEM
ABPTK
ABPTX
ABQHQ
ABRYG
ABSSG
ABTAH
ABTAI
ABXUL
ABZLS
ACGEJ
ACGFO
ACGFS
ACLSK
ACPRK
ACRBO
ACTIO
ACTOA
ADAHI
ADCVX
ADEWX
ADXPE
AECIN
AEGXH
AEGYZ
AEISY
AEKEX
AENEX
AEOZL
AEPSL
AEXSR
AEYOC
AEZRU
AFHDM
AFOLD
AFWLO
AGDLA
AGMYJ
AGRBW
AHMBA
AIAGR
AIJEM
AJWEG
AKBVH
ALLRG
ALMA_UNASSIGNED_HOLDINGS
ALQZU
AVBZW
AWYRJ
BEJHT
BLEHA
BMOTO
BOHLJ
CAG
CCCUG
COF
CQ1
CS3
DGFLZ
DGXZK
DKSSO
DU5
DXH
EAP
EBD
EBS
EFRLQ
EGDCR
EJD
EMK
EPL
EPS
ESX
E~B
E~C
F5P
FEDTE
FMBMU
FUNRP
FXNIP
G-F
GTTXZ
HZ~
IPNFZ
J.O
KDLKA
KRBQP
KSSTO
KWAYT
KYCEM
LGLTD
M4Z
MLAFT
NA5
NW-
O9-
P2P
PQEST
PQQKQ
RBICI
RIG
RNANH
ROSJB
RSYQP
S-F
STATR
TEH
TFH
TFL
TFW
TNTFI
TRJHH
UT5
UT9
V1K
VAE
ZY4
~01
~S~
07M
1TA
4B3
ABVXC
ABWZE
ABXYU
ACIKQ
ADIUE
C5A
CBZAQ
CKOZC
C~T
H13
HF~
IQODW
JLMOS
L7Y
LJTGL
QZZOY
TBH
UA1
AANPH
AAYXX
ABJNI
ACPKE
ADKVQ
ADXAZ
AHDZW
AIXGP
CITATION
HVGLF
TBQAZ
TUROJ
7QJ
ID FETCH-LOGICAL-c448t-362f3f81d4bd7a63078ff52bd7b90ae83bdc401670cd2612df30f74bfadb2923
IEDL.DBID TFW
ISSN 0960-2011
IngestDate Fri Oct 25 10:41:44 EDT 2024
Fri Nov 22 00:28:19 EST 2024
Sun Oct 22 16:04:27 EDT 2023
Tue Jun 13 19:51:20 EDT 2023
Mon May 13 12:08:44 EDT 2019
IsDoiOpenAccess false
IsOpenAccess true
IsPeerReviewed true
IsScholarly true
Issue 5
Keywords Human
Visual field disease
Vehicle driving
Vision
Neuropsychological test
Hemianopsia
Spatial ability
Cognition
Space perception
Cerebral disorder
Language English
License CC BY 4.0
LinkModel DirectLink
MergedId FETCHMERGED-LOGICAL-c448t-362f3f81d4bd7a63078ff52bd7b90ae83bdc401670cd2612df30f74bfadb2923
Notes ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
OpenAccessLink https://pure.rug.nl/ws/files/215334905/Driving_and_visuospatial_performance_in_people_with_hemianopia.pdf
PQID 57125483
PQPubID 24071
PageCount 19
ParticipantIDs informaworld_taylorfrancis_310_1080_09602010244000183
pascalfrancis_primary_14398956
crossref_primary_10_1080_09602010244000183
proquest_miscellaneous_57125483
PublicationCentury 2000
PublicationDate 2002-12-01
PublicationDateYYYYMMDD 2002-12-01
PublicationDate_xml – month: 12
  year: 2002
  text: 2002-12-01
  day: 01
PublicationDecade 2000
PublicationPlace Hove
PublicationPlace_xml – name: Hove
PublicationTitle Neuropsychological rehabilitation
PublicationYear 2002
Publisher Taylor & Francis Group
Taylor & Francis
Psychology Press
Publisher_xml – name: Taylor & Francis Group
– name: Taylor & Francis
– name: Psychology Press
References Sivak M. (CIT0018) 1981; 62
CIT0032
Kerkhoff G. (CIT0010) 1999; 15
CIT0012
Wilson B. (CIT0030) 1987; 68
Zihl J. (CIT0033) 2000
Vos J. J. (CIT0027) 1976; 173
Gauthier L. (CIT0006) 1989; 11
CIT0014
CIT0013
CIT0016
Stevens J. (CIT0020) 1996
Withaar F. K. (CIT0031) 2000
Brouwer W. H. (CIT0001) 2002
CIT0019
Kerkhoff G. (CIT0011) 1990; 61
CIT0021
Schenkenberg T. (CIT0015) 1980; 30
CIT0023
Tant M. L. M. (CIT0022) 2002
Shinar D. (CIT0017) 1991; 33
Deelman B. G. (CIT0005) 1987
De Raedt R. (CIT0003) 2000
CIT0024
CIT0004
CIT0026
CIT0007
CIT0029
De Graaf A. (CIT0002) 1991
CIT0028
CIT0009
Van Deusen J. (CIT0025) 1984; 3
CIT0008
References_xml – volume: 61
  start-page: 711
  year: 1990
  ident: CIT0011
  publication-title: Nervenarzt
  contributor:
    fullname: Kerkhoff G.
– volume-title: Visual performance in homonymous hemianopia : Assessment, training and driving (PDF)
  year: 2002
  ident: CIT0022
  contributor:
    fullname: Tant M. L. M.
– volume: 30
  start-page: 509
  year: 1980
  ident: CIT0015
  publication-title: Neurology
  doi: 10.1212/WNL.30.5.509
  contributor:
    fullname: Schenkenberg T.
– volume-title: Applied neuropsychology of attention
  year: 2002
  ident: CIT0001
  contributor:
    fullname: Brouwer W. H.
– ident: CIT0016
  doi: 10.1097/00002060-199903000-00010
– volume: 173
  start-page: 427
  year: 1976
  ident: CIT0027
  publication-title: Ophthalmologia
  contributor:
    fullname: Vos J. J.
– ident: CIT0007
  doi: 10.1080/01688638908400936
– ident: CIT0012
  doi: 10.1016/S0028-3932(98)00074-8
– volume-title: Cognitive/neuropsychological functioning and compensation related to car driving performance in older adults
  year: 2000
  ident: CIT0003
  contributor:
    fullname: De Raedt R.
– volume: 62
  start-page: 476
  year: 1981
  ident: CIT0018
  publication-title: Archives of Physical Medicine and Rehabilitation
  contributor:
    fullname: Sivak M.
– ident: CIT0009
  doi: 10.1080/09602019108520162
– volume: 68
  start-page: 98
  year: 1987
  ident: CIT0030
  publication-title: Archives of Physical Medicine and Rehabilitation
  contributor:
    fullname: Wilson B.
– volume-title: Applied multivariate statistics for the social sciences
  year: 1996
  ident: CIT0020
  contributor:
    fullname: Stevens J.
– ident: CIT0019
  doi: 10.3109/02699059409150996
– ident: CIT0023
  doi: 10.1016/S0042-6989(02)00044-5
– ident: CIT0029
  doi: 10.1136/jnnp.51.12.1481
– volume: 11
  start-page: 49
  year: 1989
  ident: CIT0006
  publication-title: International Journal of Clinical Neuropsychology
  contributor:
    fullname: Gauthier L.
– ident: CIT0024
  doi: 10.1016/S0028-3932(01)00197-X
– ident: CIT0026
  doi: 10.1037/0894-4105.4.2.87
– volume-title: Cognitieve Screening Test [Cognitive Screening Test]
  year: 1991
  ident: CIT0002
  contributor:
    fullname: De Graaf A.
– volume: 33
  start-page: 507
  year: 1991
  ident: CIT0017
  publication-title: Human Factors
  doi: 10.1177/001872089103300503
  contributor:
    fullname: Shinar D.
– ident: CIT0021
  doi: 10.1097/00006324-199312000-00007
– ident: CIT0032
  doi: 10.1076/vimr.1.1.23.4450
– volume-title: Divided attention and driving: The effects of aging and brain injury
  year: 2000
  ident: CIT0031
  contributor:
    fullname: Withaar F. K.
– ident: CIT0014
– volume: 15
  start-page: 255
  year: 1999
  ident: CIT0010
  publication-title: Restorative Neurology and Neuroscience
  contributor:
    fullname: Kerkhoff G.
– ident: CIT0008
  doi: 10.1007/s001150050355
– ident: CIT0028
– volume-title: SAN test
  year: 1987
  ident: CIT0005
  contributor:
    fullname: Deelman B. G.
– volume-title: Rehabilitation of visual disorders after brain injury
  year: 2000
  ident: CIT0033
  contributor:
    fullname: Zihl J.
– ident: CIT0013
  doi: 10.1016/S0039-6257(99)00035-1
– ident: CIT0004
  doi: 10.1093/brain/105.2.301
– volume: 3
  start-page: 49
  year: 1984
  ident: CIT0025
  publication-title: Physical and Occupational Therapy in Geriatrics
  doi: 10.1080/J148v03n02_05
  contributor:
    fullname: Van Deusen J.
SSID ssj0018046
Score 1.8970505
Snippet Practical fitness to drive was studied in 28 patients with homonymous hemianopia (HH). More specifically, visual performance during driving and...
SourceID proquest
crossref
pascalfrancis
informaworld
SourceType Aggregation Database
Index Database
Enrichment Source
Publisher
StartPage 419
SubjectTerms Adult and adolescent clinical studies
Biological and medical sciences
Brain laterality
Driving
Medical sciences
Motor vehicles
Neuropsychological tests
Organic mental disorders. Neuropsychology
Psychology. Psychoanalysis. Psychiatry
Psychopathology. Psychiatry
Visual-Spatial ability
Visually impaired people
Title Driving and visuospatial performance in people with hemianopia
URI https://www.tandfonline.com/doi/abs/10.1080/09602010244000183
https://search.proquest.com/docview/57125483
Volume 12
hasFullText 1
inHoldings 1
isFullTextHit
isPrint
link http://sdu.summon.serialssolutions.com/2.0.0/link/0/eLvHCXMwpV05T8MwFLagA2LhRoSjeGBCikjqpHYGkBBtxQILlWCLfMRSlqRqEsTP570clFLUAcZIPmI_2-_zOz4TchUwg6xj2vXh8IcLirauZNxzB4yHnAkRSVObLl7485sYjZEm57bLhcGwSrxD24Yooj6rcXNLVXQRcTeIutGJC5oJIYpArk_k24bVPJ28fvkQhNek6UBpF9Vc59P8rYUlrbTEWYrBkrKA-bLNQxcrZ3atiCa7_xzCHtlpESi9b5bMPtlIsgOy9dT62A_J3WieopWBQuP0PS2qvMCoa6gyWyQZ0DSjTfA5RUsuRdoBmeWzVB6R6WQ8fXh021cWXA1Xs9IFDWaZBdgaKMPlEPa8sDYcwIeKPJkIpowOMFnB0wb5xoxlnuWBstKoAcDDY9LL8iw5IZRrnfgGxmUtoCwWyqFkQeRFKjJaaWUdct1NcjxruDRiv6Mo_TkhDvG-iyEuawNGK4TV4nH5UTokXFOFremqvyTixc8BWhNwgXTIZSfzGHYfulRkluRVEYccAGIg2Okfuz4j293zMp5_TnrlvEouyGZhqn69mD8BsL_v2w
link.rule.ids 315,782,786,1455,1509,27934,27935,58023,59736,60525
linkProvider Taylor & Francis
linkToHtml http://sdu.summon.serialssolutions.com/2.0.0/link/0/eLvHCXMwpV3NT8IwFH9RTNSL30b8gB08mSxudGPdhcQIBCNwkURvS9euyS6DsM345_vexkTEcNDjkn6sfW3fr-_jV4BbhyliHZOmjYc_XlCkNgXzLLPFPNdjnPtCFaaLF2_8xrs9osnpVLkwFFZJd2hdEkUUZzVtbjJGVyFx9wS7yYuLqokwCmfbsIPAmNEKn_Rfv7wI3CoTdbC4SYqu8mr-1sSKXlphLaVwSZHijOnyqYu1U7tQRf3D_w7iCA4WINR4KFfNMWxFyQnsjhZu9lPodOcxGRoMbN14j9N8mlLgNVaZLfMMjDgxyvhzg4y5BjEPiGQ6i8UZTPq9yePAXDy0YEq8nWUmKjHNNCJXJ1SeaOO251q7LfwIfUtEnIVKOpSvYElFlGNKM0t7TqiFCluIEM-hlkyT6AIMT8rIVjgurRFoMVe0BXN8yw99JUMZ6jrcVbMczEo6jcCuWEp_TkgdrO9yCLLChrGQwnrxIPvI6uBuqMI2dNVYkfHy5xCwcbxD1qFZCT3ADUheFZFE0zwNXA8xosPZ5R-7bsLeYDIaBsOn8fMV7FevzVj2NdSyeR7dwHaq8kaxsj8B3-z0AQ
linkToPdf http://sdu.summon.serialssolutions.com/2.0.0/link/0/eLvHCXMwpV1LS8NAEB5sheLFtxgfbQ6ehGDaTZrNQUGsRVGLYEFvYbObhVyS0KTiz3cmaay10oMeA_vI7uzufPMGOHOYoqxj0uri448CitSWYJ5t9ZjneoxzX6hSdfHijd744JbS5FzWsTDkVkkytK4SRZRvNV3uTOnaI-6CUDcZcZEzEUThrAHrfarHhsd5PHz9MiJwu4rTweYW8bnaqPnbEAtsaSFpKXlLihw3TFeVLpYe7ZITDbf-uYZt2JxBUPO6OjM7sBYlu9B6mhnZ9-BqMIlJzWDi4OZ7nE_TnNyusUs2jzIw48SsvM9NUuWalHdAJGkWi30YD2_HN3fWrMyCJVE2KyxkYZppxK1OqDzRx0vPtXZ7-BH6tog4C5V0KFrBlooSjinNbO05oRYq7CE-PIBmkibRIZielFFX4bq0RpjFXNEXzPFtP_SVDGWoDTivNznIqmQaQbfOUfpzQwywv5MhKEoNxowIy82D4qMwwF3Rha2Yqr1A4vnPIVzjKEEa0KlpHuD1I5uKSKJ0mgeuhwjR4ezoj1N3oPU8GAaP96OHY9ioS83Y3RNoFpNpdAqNXE3b5bn-BODr8qU
openUrl ctx_ver=Z39.88-2004&ctx_enc=info%3Aofi%2Fenc%3AUTF-8&rfr_id=info%3Asid%2Fsummon.serialssolutions.com&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=Driving+and+visuospatial+performance+in+people+with+hemianopia&rft.jtitle=Neuropsychological+rehabilitation&rft.au=Tant%2C+M.L.M.&rft.au=Brouwer%2C+W.H.&rft.au=Cornelissen%2C+F.W.&rft.au=Kooijman%2C+A.C.&rft.date=2002-12-01&rft.pub=Taylor+%26+Francis+Group&rft.issn=0960-2011&rft.eissn=1464-0694&rft.volume=12&rft.issue=5&rft.spage=419&rft.epage=437&rft_id=info:doi/10.1080%2F09602010244000183&rft.externalDocID=10098935
thumbnail_l http://covers-cdn.summon.serialssolutions.com/index.aspx?isbn=/lc.gif&issn=0960-2011&client=summon
thumbnail_m http://covers-cdn.summon.serialssolutions.com/index.aspx?isbn=/mc.gif&issn=0960-2011&client=summon
thumbnail_s http://covers-cdn.summon.serialssolutions.com/index.aspx?isbn=/sc.gif&issn=0960-2011&client=summon