Expertise effect in Expertise effect in enumeration: enumeration:

subitizing or counting?subitizing or counting?

Roy Allen & Peter McGeorgeRoy Allen & Peter McGeorge

IntroductionIntroduction

Previous MOT research:Previous MOT research:• Suggests the initial activation of a limited Suggests the initial activation of a limited

number (circa 3/4) of preattentive indexes number (circa 3/4) of preattentive indexes (Pylyshyn & Storm, 1988);(Pylyshyn & Storm, 1988);

• That modality-specific (visuospatial) attentional That modality-specific (visuospatial) attentional processes are involved during the static period processes are involved during the static period of target acquisition (strategies?), and;of target acquisition (strategies?), and;

• Central executive (general attentional) Central executive (general attentional) processes predominate during dynamic target processes predominate during dynamic target tracking (iterating strategies?) (Allen, tracking (iterating strategies?) (Allen, McGeorge, Pearson & Milne, 2006)McGeorge, Pearson & Milne, 2006)

Also significant expertise/practice effect Also significant expertise/practice effect amongst:amongst:• radar operators (Allen, McGeorge, Pearson & radar operators (Allen, McGeorge, Pearson &

Milne, 2004), and;Milne, 2004), and;• action video game players (Green & Bavelier, action video game players (Green & Bavelier,

2006).2006).

experts better than novices at the MOT experts better than novices at the MOT task (circa 5/12 versus 3/12); task (circa 5/12 versus 3/12);

And more resilient to the effect of a And more resilient to the effect of a secondary visuo-verbal task (circa 4/12 secondary visuo-verbal task (circa 4/12 versus 2/12) (Allen et al., 2004). versus 2/12) (Allen et al., 2004).

How does this effect arise?How does this effect arise?

May be due to Experts’:May be due to Experts’:• better visuospatial strategies, or the strategies better visuospatial strategies, or the strategies

more effective mobilisation (Allen et al., 2004);more effective mobilisation (Allen et al., 2004);

• better fidelity of memory or their faster speed better fidelity of memory or their faster speed of processing (Green and Bavelier, 2006).of processing (Green and Bavelier, 2006).

Trick and Pylyshyn (1993, 1994) - Trick and Pylyshyn (1993, 1994) - preattentive indexes that underpin preattentive indexes that underpin performance on the MOT task also performance on the MOT task also fundamental to enumeration tasks where fundamental to enumeration tasks where fast, consistently accurate quantification is fast, consistently accurate quantification is associated with the number of active indexes,associated with the number of active indexes,

Might therefore expect expertise effect in Might therefore expect expertise effect in enumeration tasks.enumeration tasks.

Green and Bavelier (2006) and Allen and Green and Bavelier (2006) and Allen and McGeorge (2006) have reported this but only McGeorge (2006) have reported this but only for > 4 items, i.e. within counting, not for > 4 items, i.e. within counting, not subitizing, range.subitizing, range.

However, no work to date has looked at However, no work to date has looked at experts’ dual-task resilience in experts’ dual-task resilience in enumeration. Our paradigm:enumeration. Our paradigm:

Stimuli Stimuli • 1 – 8 quasi-randomly arranged plus signs (+’s) 1 – 8 quasi-randomly arranged plus signs (+’s)

in a 3 x 3 grid within a 50mm dia circle at the in a 3 x 3 grid within a 50mm dia circle at the centre of the monitor. Items jittered so as not centre of the monitor. Items jittered so as not to form straight lines;to form straight lines;

• Presented silently then with a simultaneous Presented silently then with a simultaneous tone (low-400hz, medium – 700hz, high – tone (low-400hz, medium – 700hz, high – 1000hz), counterbalanced for pitch and ear 1000hz), counterbalanced for pitch and ear (subsequently collapsed over ear)(subsequently collapsed over ear)

Pilot studyPilot study 2 novice groups - for each trial:2 novice groups - for each trial:

• IgnoreIgnore tone, indicate number of items (fast but tone, indicate number of items (fast but accurate) using numeric keys above accurate) using numeric keys above “QWERTY” keys – passive dual task (affect “QWERTY” keys – passive dual task (affect subitizing range?),subitizing range?),

• ReactReact to tone, still indicate number of items to tone, still indicate number of items (fast but accurate) but switch between (fast but accurate) but switch between numeric keys above “QWERTY” keys and numeric keys above “QWERTY” keys and numeric keypad dependent upon tone pitch – numeric keypad dependent upon tone pitch – active dual task (affect counting range?);active dual task (affect counting range?);

• Presentation time was 26ms (2 x refresh rate).Presentation time was 26ms (2 x refresh rate).

Task x Number of itemsTask x Number of items (F(3.02, 93.64) = 5.21, MSE = 2628.20, p < .01, (F(3.02, 93.64) = 5.21, MSE = 2628.20, p < .01, pp

2 2 = 0.14)= 0.14)

Task only produces significant performance differences (independent t-Task only produces significant performance differences (independent t-tests) for 4- (t(31) = 3.46, p < .006), 5- (t(31) = 4.30, p < .006) & 6-item tests) for 4- (t(31) = 3.46, p < .006), 5- (t(31) = 4.30, p < .006) & 6-item (t(31) = 4.02, p < .006) trials.(t(31) = 4.02, p < .006) trials.

Task x Number of items interaction

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react

REACT condition clearly has debilitating REACT condition clearly has debilitating effect over counting (>3) range,effect over counting (>3) range,

no effect of IGNORE condition, i.e. no no effect of IGNORE condition, i.e. no

reduction in performance across subitizing reduction in performance across subitizing range,range,

curiously, in REACT condition RTs to tone curiously, in REACT condition RTs to tone trials were slower, yet in IGNORE condition trials were slower, yet in IGNORE condition RTs to tone trials were significantly faster RTs to tone trials were significantly faster (Tone x Task (F(1, 31) = 11.36, MSE = (Tone x Task (F(1, 31) = 11.36, MSE = 1611718.17, p < .01, 1611718.17, p < .01, pp

22 = 0.27) = 0.27)

First experiment:First experiment:• previous REACT condition group versus previous REACT condition group versus

matched group of prospective radar matched group of prospective radar operators, operators, beforebefore training (i.e., passed training (i.e., passed requisite aptitude tests)requisite aptitude tests)

• presentation times were 26ms and presentation times were 26ms and 208ms (refresh multiples) – 208ms (refresh multiples) – subitizing/counting?subitizing/counting?

Expert x Number of itemsExpert x Number of items (F(3.02, 118.50) = 8.79, MSE = 2298.57, p (F(3.02, 118.50) = 8.79, MSE = 2298.57, p

< .01, < .01, pp22 = 0.23) = 0.23)

Task only produces significant performance differences (independent t-Task only produces significant performance differences (independent t-tests) for 6 (t(30) = 5.49, p < .006) & 7 (t(30) = 3.78, p < .006) items tests) for 6 (t(30) = 5.49, p < .006) & 7 (t(30) = 3.78, p < .006) items

Expert x Number of items interaction

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Unusually, prospective experts’ 5-item performance poorer Unusually, prospective experts’ 5-item performance poorer than 6-item though RTs were sig. faster (i.e., no greater than 6-item though RTs were sig. faster (i.e., no greater cognitive load in former). Also:cognitive load in former). Also:

Tone x Number of itemsTone x Number of items (F(4.05, 121.62) = 5.37, MSE = 622.41, p < .01, (F(4.05, 121.62) = 5.37, MSE = 622.41, p < .01, pp

22 = 0.15) = 0.15)

Task only produces a significant performance difference, as judged by Task only produces a significant performance difference, as judged by paired t-tests, for 5- (t(31) = 3.17, p < .006) & 8-item (t(31) = 3.02, p paired t-tests, for 5- (t(31) = 3.17, p < .006) & 8-item (t(31) = 3.02, p < .006)trials.< .006)trials.

Tone x Number of items interaction

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tone

Why does the REACT condition only affect prospective experts on Why does the REACT condition only affect prospective experts on 5-item trials?5-item trials?

Indexes amodal? Task-switching – response keys and Indexes amodal? Task-switching – response keys and subitizing/counting?subitizing/counting?

Greater variability at 5-item trials; decrease in performance primarily due to under-estimationGreater variability at 5-item trials; decrease in performance primarily due to under-estimation

Response accuracy collapsed over time

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Second experiment:Second experiment:

• previous prospective radar operators, previous prospective radar operators, beforebefore training versus same group training versus same group afterafter basic training (5 weeks)basic training (5 weeks)

• presentation times were 26ms and presentation times were 26ms and 208ms (refresh multiples) – 208ms (refresh multiples) – subitizing/counting?subitizing/counting?

• Crucial finding – effect of tone (or task-Crucial finding – effect of tone (or task-switching) at 5-item trials disappears switching) at 5-item trials disappears with trainingwith training

When (before/after training) x Tone (present/absent) x Number of items (1 When (before/after training) x Tone (present/absent) x Number of items (1 – 8) (F(2.86, 34.29) = 3.64 MSE = 898.37, p < .01, – 8) (F(2.86, 34.29) = 3.64 MSE = 898.37, p < .01, pp

22 = 0.23 = 0.23

5-item trials differ significantly t(14) = 3.06, p < .015-item trials differ significantly t(14) = 3.06, p < .01

When x tone x Number of items - pre-training

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No significant differencesNo significant differences

When x Tone x Number of items - post-training

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Response accuracy collapsed over time

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Preliminary studies – presently repeating, but:Preliminary studies – presently repeating, but:

A secondary, switching task, directed by an A secondary, switching task, directed by an auditory tone, seems to have a debilitating effect auditory tone, seems to have a debilitating effect on enumeration, but only within the counting not on enumeration, but only within the counting not subitizing range;subitizing range;

Prospective experts out-perform novices on the Prospective experts out-perform novices on the dual-task enumeration task, but only in counting dual-task enumeration task, but only in counting range;range;

Prospective experts’ performance seems to “dip” Prospective experts’ performance seems to “dip” at 5-item trials, but this effect disappears after at 5-item trials, but this effect disappears after trainingtraining