Experimental Psychology Course Notes PDF

ATTENTION COURSE OF EXPERIMENTAL PSYCHOLOGY Università Cattolica del Sacro Cuore MILAN CLAUDIA REPETTO  TOC * Definitions and functions * Spatial attention * Visual attention: features integration theory * Attention control * Object-b...

ATTENTION COURSE OF EXPERIMENTAL PSYCHOLOGY Università Cattolica del Sacro Cuore MILAN CLAUDIA REPETTO  TOC * Definitions and functions * Spatial attention * Visual attention: features integration theory * Attention control * Object-based attention * When attention fails: “experimental” deficit and neurologic deficit  Definition and functions Have you ever thought about how many stimuli reach our senses in each moment? Attention is a selection process implemented by the brain against the continuous and large flow of stimuli coming from the sense organs  Definition and functions This selection implies that some stimuli will be processed in details, whereas other ones will be neglected àmetaphor of sieve Selection is necessary because our cognitive system has limited resources  SPATIAL ATTENTION * Spatial attention can be used to direct our interest towards a portion of the space or of the visual field BUT * Not necessarily the portion of the space towards which the attention is directed is the same we are staring at (i.e. “ to see out of the corner of your eye”)  SPATIAL ATTENTION: Posner’s paradigm * Posner has studied the shift of attention in space by means of the spatial cues * His classic paradigm is run in a laboratory, with the aid of a computer that records reaction times (time spent to provide an answer, as required by the experimental task) + + +  SPATIAL ATTENTION: Posner’s paradigm * The provided cue was correct in 80% of the trials (valid trials) and incorrect in 20% of the trials (invalid trials) * Results demonstrate that people are faster in answering to valid trialsà therefore the shift of attention towards the space where the target will appear increases information speed of processing  SPATIAL ATTENTION: Posner’s paradigm * Metaphor of attention as spotlight * Metaphor of lens focus  VISUAL ATTENTION: Treisman’s Features Integration Theory * It refers to the study of the mechanisms underlying visual research * Paradigm used to study which characteristics of the target (with respect to the distractors, i.e. the other elements presented that are not the target) make its search more or less efficient, and to infer the mechanisms (attentive and otherwise) adopted by the visual system to analyze the scene  VISUAL ATTENTION: Treisman’s Features Integration Theory * If an element is very distinctive from the others (it has a characteristic that makes it unique) its identification is very quick and does not depend on the number of distractors  VISUAL ATTENTION: Treisman’s Features Integration Theory * If the target must be identified by combining two characteristics or is very similar to the distractors then the RTs are proportional to the number of distractors  nt ive a t t e Pre- attentive Elements’ number  ATTENTION CONTROL * Automatic vs voluntary orientation Quick presentation of Posner’s paradigm peripheral light signal +  ATTENTION CONTROL * Automatic vs voluntary orientation Independent of the cognitive load Resistant to suppression It doesn't depend on expectations  ATTENTION CONTROL * Interaction between automatic and voluntary factors: they usually work in synergy, but sometimes they compete  ATTENTION CONTROL * Interaction between automatic and voluntary factors: they usually work in synergy, but sometimes they compete Attention can be automatically captured by irrelevant elements but… According to the Contingent Capture Theory this only happens if the distractor is similar to the target for some characteristics Contingent Capture Theory  OBJECT-BASED ATTENTION * According to this hypothesis, attention does not move only according to spatial coordinates but it is captured by objects * Although objects and space are related, it can be shown that attention acts on the basis of the objects regardless of the space they occupy  OBJECT-BASED ATTENTION “is the outline of “is the outline of the square the square dashed? Is the dashed? Is the triangle tilted?” square tilted?” RTs are faster in the second case because it is not necessary to shift attention from the representation of one object to that of the other  OBJECT-BASED ATTENTION * The hypothesis that shapes organize the percept had already been advanced by Gestalt * At a pre-attentive level, segmentation into perceptual units takes place * Perceptual units are formed following the laws of grouping * This implies that distant objects can be part of a unit but they respect the rule of Similarity or common Movement  When attention fails: "experimental deficits" Attentional blink Attention studied through its "failures", induced by ad hoc experimental procedures Change blindness  Attentional blink * Difficulty in discriminating a target stimulus when the attention is already engaged in processing another stimulus LET’S TRY TOGETHER! ATT1: Is there an x or a y? Att2 e Att3: spot the red letter and the presence of X or Y  Change blindness Video “the door study” https://www.youtube.com/watch?v=FWSxSQsspiQ&t=12 s  Change blindness * Inability to consciously notice relevant changes in the scene when these occur in conjunction with other disturbing visual events (screen flash), or when suddenly other objects appear on the scene * Flicker paradigm: repetition of images in sequence with a short blank (no images) in the between Let’s see an example! http://nivea.psycho.univ- paris5.fr/Mudsplash/Nature_Supp_Inf/Movies/Movie_Lis t.html [Notre Dame; Parking]  Let’s test ourselves https://www.youtube.com/watch?v=vJG698U2Mvo https://www.youtube.com/watch?v=IGQmdoK_ZfY  When attention fails: neurological deficits Specific brain lesions can lead to attention deficit, in the absence Neglect of concomitant perceptual deficits Inability to process stimuli located in the left side of the visual field  Neglect: clinical picture and assessment * Pathology usually resulting from injury to the right parietal cortex * The “neglected” portion of the visual field varies from patient to patient * It also involves peripersonal space and one's own body * It often spontaneously regresses after the acute phase of the trauma Visual field scan in patient with neglect (in yellow eye movements recording) Barrage test Drawing copy Spontaneous drawing