Study: Depression affects visual perception … making it more accurate

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The bright­ness of Fig­ures A and B is exact­ly the same, but they are per­ceived dif­fer­ent­ly due to a dif­fer­ence in the back­ground. This illu­sion was per­ceived sim­i­lar­ly by the patients and healthy con­trol sub­jects. The con­trast of Fig­ures C and D is exact­ly the same as well, but the per­cep­tion of this illu­sion was weak­er among the depressed patients than the con­trol sub­jects. (Salmela et al, J. Psy­chi­a­try Neu­rosci, 2021)

Depres­sion affects visu­al per­cep­tion (press release by Uni­ver­si­ty of Helsinki):

Researchers spe­cialised in psy­chi­a­try and psy­chol­o­gy at the Uni­ver­si­ty of Helsin­ki inves­ti­gat­ed the effects of depres­sion on visu­al per­cep­tion. The study con­firmed that the pro­cess­ing of visu­al infor­ma­tion is altered in depressed peo­ple, a phe­nom­e­non most like­ly linked with the pro­cess­ing of infor­ma­tion in the cere­bral cortex.

In the study, the pro­cess­ing of visu­al infor­ma­tion by patients with depres­sion was com­pared to that of a con­trol group by util­is­ing two visu­al tests. In the per­cep­tion tests, the study sub­jects com­pared the bright­ness and con­trast of sim­ple patterns.

“What came as a sur­prise was that depressed patients per­ceived the con­trast of the images shown dif­fer­ent­ly from non-depressed indi­vid­u­als,” says Acad­e­my of Fin­land Research Fel­low Vil­ja­mi Salmela … “It would be ben­e­fi­cial to assess and fur­ther devel­op the usabil­i­ty of per­cep­tion tests, as both research meth­ods and poten­tial ways of iden­ti­fy­ing dis­tur­bances of infor­ma­tion pro­cess­ing in patients,” Salmela says.

Per­cep­tion tests could, for exam­ple, serve as an addi­tion­al tool when assess­ing the effect of var­i­ous ther­a­pies as the treat­ment progresses.

The Study:

Reduced visu­al con­trast sup­pres­sion dur­ing major depres­sive episodes (Jour­nal of Psy­chi­a­try and Neu­ro­science). Full study avail­able Here (free, opens PDF). From the Abstract:

  • Back­ground: Pre­vi­ous stud­ies have sug­gest­ed that pro­cess­ing of visu­al con­trast infor­ma­tion could be altered in major depres­sive dis­or­der. To clar­i­fy the changes at dif­fer­ent lev­els of the visu­al hier­ar­chy, we behav­ioural­ly mea­sured con­trast per­cep­tion in 2 cen­tre-sur­round con­di­tions, assess­ing reti­nal and cor­ti­cal processing.
  • Meth­ods: As part of a prospec­tive cohort study, our sam­ple con­sist­ed of con­trols (n = 29; 21 female) and patients with unipo­lar depres­sion, bipo­lar dis­or­der and bor­der­line per­son­al­i­ty dis­or­der who had base­line major depres­sive episodes (n = 111; 74 female). In a bright­ness induc­tion test that assessed reti­nal pro­cess­ing, par­tic­i­pants com­pared the per­ceived lumi­nance of uni­form patch­es (pre­sent­ed on a com­put­er screen) as the lumi­nance of the back­grounds was var­ied. In a con­trast sup­pres­sion test that assessed cor­ti­cal pro­cess­ing, par­tic­i­pants com­pared the per­ceived con­trast of grat­ings, which were pre­sent­ed with collinear­ly or orthog­o­nal­ly ori­ent­ed backgrounds.
  • Results: Bright­ness induc­tion was sim­i­lar for patients with major depres­sive episodes and con­trols (p = 0.60, d = 0.115, Bayes fac­tor = 3.9), but con­trast sup­pres­sion was sig­nif­i­cant­ly low­er for patients than for con­trols (p < 0.006, d = 0.663, Bayes fac­tor = 35.2). We observed no sta­tis­ti­cal­ly sig­nif­i­cant asso­ci­a­tions between con­trast sup­pres­sion and age, sex, or med­ica­tion or diag­nos­tic sub­group. At fol­low-up (n = 74), we observed some nor­mal­iza­tion of con­trast perception.
  • Lim­i­ta­tions: We assessed con­trast per­cep­tion using behav­iour­al tests instead of electrophysiology.

The Study in Context: