Multitasking

Question 1

COGNITIVE CAPACITY

Answer 1

• even in singular tasks, cognitive capacity = limited
• memory retrieval/decision making = time consuming
• input processes (ie. syntactic parsing) handling limits
• representational/storage capacity (ie. WM) = limited
• limits = obvious when resources shared via tasks ie. more than 1 in certain time/some = time critical; simultaneous/switch between

Question 2

MULTI-TASKING

Answer 2

• ie. cooking/ironing/baby monitoring/phone calling
• ie. chef/pilot/taxi driver
• limitations = important theoretically (global computational architecture of brain) + practically (efficiency/risk/human error)

Question 3

MUTLI-TASKING DEMANDS

Answer 3

• competition for shared resources in simultaneous tasks (dual-task interference)
• task-switching = set-shifting/task shifting costs/retrospective memory (what’s left to do?)/prospective memory (ie. trigger monitoring (is it time to do X?)/trigger meaning (ie. what is X?))
• OVERALL not single competence

Question 4

EXECUTIVE CONTROL DEMANDS

Answer 4

• planning/scheduling/prioritising/coordinating the two task streams
• trouble shooting/problem solving when it goes wrong/unexpected conditions arise
• overall critical

Question 5

USING PHONE WHILE DRIVING

Answer 5

• epidemiological studies = ^ accidents; relative risk similar to driving at legal alcohol limit
• observational studies = delayed braking at T-junction
• experimental studies = impaired braking/hazard detection especially in young drivers

Question 6

RELATIVE RISK X USING PHONE WHILE DRIVING

Answer 6

STRAYER, DREWS & CROUCH (2006)

• pp in simulator; follows pacer car in motorway 15m; tries distance maintenance; pacer sometimes brakes
• baseline VS alcohol (80mg/100ml) VS casual hh/hf mobile talk (initiated before; terminated after measure)
• phone = slower reactions/recovery/^ tail-end collisions
• alcohol = ^ aggressive (closer following/harder braking)
• NO STATSIG between hh/hf!

Question 7

DRIVING SIMULATOR STUDIES +

Answer 7

STRAYER (2015)
HF MOBILE
- < 50%: anticipatory glances to safety critical areas (ie. parked lorry blocking zebra)/later recognition memory of driving environment objects/P300 amplitude to brake light onset in followed car
- ^ unsafe lane change prob
- crash risk data suggests dif effect in direct talking; passengers = sensitive to driver’s load (ie. stop talking/wait for reply); help spot hazards/distractions

Question 8

LAB DUAL-TASK INTERFERENCE MEASURING

Answer 8

• only 2 tasks designed measurement/manipulation

- typically measures performance on tasks A/B alone/A+B; questions performance deterioration in cs

Question 9

DUAL-TASK INTERFERENCE SOURCES

Answer 9

• slower/inaccurate performance possibly via:
• specialised domain-specific resource competition (ie. body effectors/sense organs/brain modules/processes/representations)
• general purpose processing capacity competition (ie. central processor/GP processing resource pool)
• limited executive control mechanism capacity (sets up/manages system info flow)/subliminal control strategies

Question 10

DOMAIN-SPECIFIC RESOURCE COMPETITION

Answer 10

• two continuous speech inputs cannot be understood/repeated simultaneously BUT both can be monitored for target word-meaning
• spatial tracking task interferes w/visual imagery to remember (both use visuo-spatial working memory)
• 2 dif tasks use same perceptual processes/response mechanisms/central translation/coordination processes = dual-task interference UNLESS info rate low enough to switch resource use
• question of concurrent performance by any task pair = some interference?

Question 11

GENERAL-PURPOSE PROCESSOR COMPETITION

Answer 11

BROADBENT’S P-SYSTEM (1958)

• analogous to standard late 20th century digital computers w/single CPU
• assumed required for pattern recognition/memory access/decision making/action selection/awareness
• others (ie. POSNER (1978) identified consciousness w/central processor

Question 12

GENERAL-PURPOSE RESOURCE POOL COMPETITON

Answer 12

KAHNEMAN (1975)

• first proposed shared concurrent task effort
• capacity varies on:
• over/within people (alertness)
• sustained/available attention (diminishes w/boredom/fatigue; ^ w/time of day (NOT post-lunch dip)/moderate stressors (noise/heat)/emotional arousal/conscious effort

Question 13

CENTRAL PROCESSOR/RESOURCE POOL ASSUMPTION

Answer 13

• capacity shared by any 2 tasks
• cap demand sum + NO exceeding total = no interference; exceeding = interference/^ 1 task difficulty = cap reduction for other
• hard to know a priori how much cap task needs
• test theory via pair use in tasks; obvs each would require all/most central capacity

Question 14

DEMANDING COMBINED TASKS W/O INTERFERENCE

Answer 14

ANTONIS & REYNOLDS (1972)
- Reading uni Y3 music students (competent pianists)
- A = G2(e)/G4(h) sight read; B = Austen(e)/Old Norse(h) novel shadow prose; little practice (10m shadowing for 2 no omission trials; 2m sight reading, 7m dual tasks)
- 2 sessions of dual tasks for easy/hard combos + 1m sight reading/shadowing alone (order balanced)
RESULTS
- shadowing/errors = no dif w/w/o concurrent sight; concurrent shadowing = no ^ sight errors
- ^ h shadow/sight errors (difficulty manipulations work) BUT neither affected by session 2

Question 15

DEMANDING COMBINED TASKS W/O INTERFERENCE (MORE EXAMPLES)

Answer 15

SHAFFER (1975)
- tasks combined w/o apparent interference
- skilled visual-type copying combined w/prose shadowing = no interference
NORTH (1977)
- one task insensitive to difficulty of other
- continuous tracking/digit = key task of: key press/before present one/successive pair digit identification
- no difficulty effect of task on tracking delays

Question 16

NO CENTRAL GENERAL-PURPOSE PROCESSOR/RESOURCE

Answer 16

ALLPORT (1980)

• complex input-output translation task pairs can be combined w/little/no inter if using non-overlapping modules (dif input codes/modalities/action systems/central representations/networks)
• SO general-purpose central processor = unnecessary
• BUT even when tasks use dif modules some inter arises via coordination/control demands (ie. specialised executive processes load consequence)

Question 17

NO CGP X DRIVING HYPOTHESIS

Answer 17

• rebooted hypothesis:
  a) driving/navigation (visuo/spatial input -> hand/foot response) + conversation (speech input meaning speech production) = v dif module use?
• YES/NO! dif input/output modalities BUT both require mental model construction (ie. driving = route/goals/progress/road-signs/observed events/potential hazard prediction etc.)
• driving mental model construction interfered via convo asking for visuo-spatial arrangements (ie. “when we get to X, do you know how to find Y?”)/imagine movements

Question 18

IMPORTANCE OF PRACTICE

Answer 18

SPELKE HIRST & NEISSER (1976)

• uncombinable w/o inter tasks = easier combined w/practice (ie. changing gear)
• 85h practice reading stories (comprehension) simultaneously w/dictation writing (6w) then reading concurrent w/writing spoken words (11w)
• some pp = little dual-task inter as:
• practicing 1 task automates it (reduces executive control of constituent processes need)
• practicing combo tasks develops optimal control strategies for combining the specific task pair

Question 19

BROADBENT’S OBJECTION TO ALLPORT EXPS

Answer 19

BROADBENT (1982)

• continuous task pairs (ie. shadowing/sight reading) =
• some input predictability/anticipation
• substantial input/output lag (temp WM storage)
• SO could still be central processor task switching (time-sharing); while servicing one task, input/output in other stored in WM buffers
• processor-switching revealed in tests is concurrent tasks w/small input/output lags used + next stimuli = unpredictable (ie. RT tasks)

Question 20

PRP (PSYCHOLOGICAL REFRACTORY PERIOD)

Answer 20

WELFORD (1952)
- 2 choice RT tasks
- stimulus onsets separated via variable/short interval (SOA (stimulus onset asynchrony))
SCHUMACHER et al (2001)
- 1 = audio-vocal (low/m/high tone = 1-3)
- 2 = visuo-manual (000 = index/m/ring finger)
- PRP effect (robust to practice) occurs even when stimuli/responses for 2 tasks = dif modalities

Question 21

PASHLER’S PRP THEORY

Answer 21

PASHLER (1990)

• response selection = bottleneck; performed only p/task; if stimuli 2 arrives/identified, must wait til response selection mechanism = free
• capacity limitation must be in central translation processes (perceptual processes -> central trans -> response execution)

Question 22

PRP CRITICISMS

Answer 22

• RT task pairs w/no PRP interference exist (ie. GREENWALD & SHULMAN (1973); repeat spoken letter word + move lever w/arrow); all w/natural/practiced input/output mapping
• observed PRP effect = not via structural bottleneck but cautious control strategy pps adopt to avoid responding to stimuli 2 (ie. MEYER & KIERAS (1997))
• if pps trained w/liberal strategy = PRP disappears
• dual task cost in PRP paradigm via bottleneck (response selection mechanism) VS soft capacity limits w/control strategies = still questioned
• response-selection mechanism = NOT GPP

Question 23

SUMMARY

Answer 23

• much inter between simultaneous tasks = via specialised resources competition
• general purpose processing capacity for high cognition (consciousness?) = popular BUT few evidence
• dual task inter cases interpreted as via GPP limited capacity competition/generic response-selection mechanism = better explained as:
• domain-specific resource competition
• specialised executive control mechanism capacity
• inefficient control strategy use