{"id":40300,"date":"2020-03-23T13:28:26","date_gmt":"2020-03-23T13:28:26","guid":{"rendered":"http:\/\/www.labri.fr\/perso\/barla\/blog\/?p=40300"},"modified":"2020-03-23T13:28:28","modified_gmt":"2020-03-23T13:28:28","slug":"computational-psycho-physics","status":"publish","type":"post","link":"https:\/\/www.labri.fr\/perso\/barla\/blog\/?p=40300","title":{"rendered":"Computational Psycho-physics?"},"content":{"rendered":"<p id=\"top\" \/>\n<h3 class=\"wp-block-heading\">Goals of 3D visual perception<\/h3>\n\n\n\n<ol class=\"wp-block-list\"><li> Identify: what properties of light reaching eyes can be used to  perceive X ? <\/li><li>Explain: what mechanisms in a brain are responsible for  perceiving X ? <\/li><\/ol>\n\n\n\n<p>Main challenge: find a systematic approach, allow for theory formulation  and validation\/falsification.<br>Goal 1 should be related to evolution: availability of optical  properties and relevance to survival\/reproduction. <br>Goal 2 should be answered at different levels: functional,  neurophysiological, chemical, etc. <\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Classical psychophysics <\/h3>\n\n\n\n<p>Scientific methodology centered on evaluating capacities\/abilities of  the HVS for specific tasks. Goals 1 and 2 are most often addressed in discussions, only rarely  explicitly tested for in experiments. <\/p>\n\n\n\n<p>One reason is the difficulty to apply classical psychophysics to complex  (ecologically-relevant) stimuli. <\/p>\n\n\n\n<p>Let&#8217; s review the different stages of the experimental approach and  comment on limitations w.r.t. 3D perception.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Stimuli <\/h4>\n\n\n\n<p>Initially simple (grating\/pedestal), with variables directly controlling  image. Most often not ecologically meaningful > move to real or synthetic  complex stimuli. Now variables instead control the image formation process (more or less  remote from image). <\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Tasks <\/h4>\n\n\n\n<p>Static (not interactive): predetermined set of images and motion. <br>Labels, probes: various ways to affect outcome! <br>AFC: comparisons across different scenes (unnatural)  <\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Computational psychophysics<\/h3>\n\n\n\n<p>Exists to some extent (image statistics), but relevance and scope remain  limited: both scene and observer are static. <\/p>\n\n\n\n<p>Observe that goal 1 is independent of the subject for the most part:  ecological optics, only requires a (moving) viewpoint. <br>Aim to characterize spatio-temporal optical array structure from  physical 3D scene definition that could potentially be used for perception.  <\/p>\n\n\n\n<p>In contrast, goal 2 should be highly dependent on the subject, which  should be considered as a dynamical process. Now the objective is to find (one or more) &#8220;attractors&#8221; that settle  perception in a stable state for a given scene. <\/p>\n\n\n\n<p>Let&#8217;s revisit the different experimental stages so that goals 1 and 2  are at the core of the scientific investigation. <\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Stimuli<\/h4>\n\n\n\n<p>Not only rendering\/composited\/drawn image, but also additional feature  images. Different approaches to alter the image features, so as to probe their  impact on perception. <\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Task<\/h4>\n\n\n\n<p>Dynamic: interactive, track body motion (e.g., eye and head) > light field?<br>One scene that gets modified by the subject herself: avoid unnatural  saccades (AFC) or unnatural stimulus (gauge). <\/p>\n\n\n\n<p>Local modifications: shape reconstructed by subject and compared in  different lighting until perceived the same. <br>Global modifications: input mirror material modified in a 2D latent  space and compared in different lighting&#8230; <\/p>\n","protected":false},"excerpt":{"rendered":"<p>Goals of 3D visual perception Identify: what properties of light reaching eyes can be used to perceive X ? Explain: what mechanisms in a brain are responsible for perceiving X ? Main challenge: find a systematic approach, allow for theory formulation and validation\/falsification.Goal 1 should be related to evolution: availability of optical properties and relevance &#8230; <a title=\"Computational Psycho-physics?\" class=\"read-more\" href=\"https:\/\/www.labri.fr\/perso\/barla\/blog\/?p=40300\" aria-label=\"Read more about Computational Psycho-physics?\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[651],"tags":[],"class_list":["post-40300","post","type-post","status-publish","format-standard","hentry","category-thoughts"],"_links":{"self":[{"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/posts\/40300","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=40300"}],"version-history":[{"count":1,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/posts\/40300\/revisions"}],"predecessor-version":[{"id":40301,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/posts\/40300\/revisions\/40301"}],"wp:attachment":[{"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=40300"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=40300"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=40300"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}