Attention and control practical Flashcards
the visual search exp
Can we process info from whole visual field at once? Or must we process one object (/region) at a time?
Depends on what kind of processing required?
Treisman and Gelade (1980) measured time taken to search for target object differing from background objects, and varied number of objects N in display:
- If process one object at a time, then larger N is, longer should take to detect prescence/absence of target
- If can perf necessary discrimination for all objects on display simultaneously, time taken to detect presence absence target shouldn’t increase much with N
Target differed from background items by:
- Single feature
- combination (/conjunction) of features
On each trial, see array of ‘objects’ - blue, green/brown, Ns, Xs/Os
the Stroop effect
First reported by Stroop (1935)
Much harder to name colour of names of colour than other symbols
Exp on:
- Selective attention - asking subject to selectively attend to one of two attributes of object and ignore other
- Control of cog processes - have 2 familiar stimulus-to-action mappings in comp - greater RT for naming coloured cowards than control items (interference/response conflict effect) measures difficulty of suppressing more practiced but irrelevant reading response
- Effects of emotion on attention and control because in some lists we use emotion words
control of task-set
Each stimulus in current env affords many tasks
Can select ‘at will’
- Which stimulus/attribute to process - Attentional control
- Which cog task to perf- Intentional control
- According to current goals
- Appropriate organisation of processes to carry out particular task = ‘task-set
the task switching exp
The processes that reorganise the mind to do one task rather than another = ‘executive/control’ processes
visual search
Anne Treisman (PhD Oxford, 1960)
exp design IVs
no. of items on display - no. varies unpredictably from trial to trial, objects positioned randomly in grid
Target present on half trials, absent on others - varies unpredictably from trial to trial
Target differs from background by either
- Single feature
- A feature conjunction
Manipulated between blocks of trials, order balanced
exp design DVs
RT
Error rate
prediction: illusory conjunctions
Very brief display (200ms) followed by pattern mask: P told to attend to and report lateral digits - then cued to report object in one of 4 (unattended) locations by features: e.g. ‘big outline red circle
More reports of erroneous conjunctions of features from display: e.g. outline green circle’ than would be predicted by random guessing from the set of colours, shapes etc. used in the exp
Need attention to bind features together
Patients who have difficulty finding conjunction targets (cannot find Wally) and are esp. susceptible to illusory conjunctions (Balint’s syndrome) and can search for only one feature
visual attention in complex scenes
Details of Treisman’s account of visual search have been challenged
- For many target/distractor pairs, pref in between ‘serial search’ patterns dn ‘pop-out’ pattern
- Slow of search function depends on target-distractor similarity (not just conjunction v single-feature)
however, amendments to theory leave idea intact that features of not-yet-attended objects not ‘bound’ into object description
Adds to other demonstrations that processing unattended visual objects shallow
response neg v neutral words in depression
Mitterschifthaler et al. (2008)
Main effect of valence (sad > neutral), group (MDD > controls), valence x group (MDD > controls for negative, not neutral words).
L ACC activation (negative > neutral) was greater in MDD than controls. ACC activation correlated positively with latencies to negative emotional words in MDD (r = 0.68, p = 0.003). Rostral ACC involved in attention allocation and conflict monitoring
Slowing of 100ms (84ms on average across clinical studies)
response to neg v neutral words in healthy controls
Emotional stroop shows slowing to disorder-relevant words (threat words in anx, injury-related in PTSD, food in bulimia, exam/achievement in students before exams etc)
Both ‘relatedness to current concern’ and negativity cause greater interference in patients
Unclear what it really measures - selective attention, interference from emotional reaction, ‘cog avoidance’ (suppressing the meaning of word), mental preoccupation?
Effects seen with subliminal presentation
emotional stroop
Colour name neg, pos, neutral words
Time taken to name colour increases as attention to emotion word increases
Patients with depression tend to be slower to name the colour of neg words (indirect neg bias)
Used as an indirect measure of emotional bias in psych disorders (as opposed to e.g. recognising emotions in faces, which is a direct measurement of bias)
