1. Are the effects of age of acquisition across words, objects, and faces the same?
Viv Moore
University of Kent.
Jamie Smith-Spark
Tim Valentine
Goldsmiths College, University of London.
Acknowledgements: ESRC Grant R

2. Talk Outline. Introduction. Rationale for the course of study.
Experiment.
Conclusions.

3. Introduction I.
Age of acquisition (AoA) – faster processing of early-acquired than late-acquired words.
Empirical effects of AoA:
Object naming (Morrison et al., 1992).
Word reading (Gerhand & Barry, 1998).
Visual LDT (Gerhand & Barry, 1999).
Auditory LDT (Turner, Valentine, & Ellis, 1999).
Object perception (Moore, Smith-Spark, & Valentine, in press).
Written motor output (Bonin, Fayol, & Chalard, 2001).
Multiplication facts (Adams & Muncer, in press).

4. Introduction II.
Many word frequency studies fail to control for effects of AoA.
Sometimes effects argued to be ‘interchangeable’ (Seidenberg et al., 1996) or reinterpreted as ‘trajectory frequency’ (Zevin & Seidenberg, 2002).
AoA and frequency effects are highly correlated.

5. Introduction III.
But cannot explain evidence of AoA in domains where correlations not so strong, e.g. names and faces of celebrities.
Face & name naming (Moore & Valentine, 1998).
Face & name perception (Moore & Valentine, 1999).

6. The AoA Effect: Locus or Loci?
The ‘phonological completeness’ hypothesis (Brown & Watson, 1987).
Neural plasticity (Ellis & Lambon Ralph, 2000).
Set up of a Specialised Processing System (Moore & Valentine, 1999; Moore, 2003).
Cumulative frequency (Zevin & Seidenberg, 2002).

7. Empirical Effects of AoA.
Perceptual register.
Motor output.
Semantic?

8. Phonological Completeness.
Early items are represented in a more complete form than late-acquired items. Late items are fragmented, requiring re-assembling for production.
People processing problems for the locus:
e.g. 2 x John Smiths acquired both early & late.
Problematic for the mechanism:
AoA advantage for objects and faces without naming.
Phonological completeness hypothesis:
Phonological representations of early-acquired words should be stored in a more complete form than representations of later acquired words.
Effect located at speech output lexicon by Morrison et al. (1992).
Automatic activation of phonology in output lexicon on visual lexical decision tasks.
Learning during a ‘critical period’.
But challenged by AoA in famous name and face processing tasks, particularly when no verbal response is required (e.g. Moore & Valentine, 1999).
Celebrity stimuli are learnt later in life.

9. Neural Plasticity. AoA is a ‘natural property’ of back propagation.
No catastrophic interference.
Early patterns reduced network’s plasticity
Sequential learning (as people learn).

10. Neural Plasticity: Simulations.
Monaghan & Ellis (2002).
Two assumptions:
Each network represents an individual perceptual register.
Facilitation will occur for the learning of new highly correlated items.
Semantic?

11. SSPS Hypothesis.
When new important exemplars are encountered that cannot be mediated by existing semantic knowledge, a level of affect is raised to almost a pre-startle level (Moore, 2003).
Heightened affect is responsible for setting up a dedicated and specialised processing system (or module) for mediating further exemplars of the same type of material.
SSPS:
AoA effect reflects order of acquisition of items in a specific stimulus domain, rather than age per se at which they were acquired.
Initial exemplars of a new type of information stimulate an attentional orienting response, effectively initialising a specialised processing system.
AoA should affect any perceptual or lexical processing task for which specialised representations have been established (Moore, 2000).

12. Predictions.
There should be an effect of AoA on all perceptual and all motor tasks.
An SSPS will occur at an individual level based on a person’s prior knowledge.
Therefore, semantic tasks will not be affected by AoA in the same way as perceptual and motor tasks.

13. Rationale for the Course of Study.
If AoA affects processing in all domains, then it should influence performance on a semantic decision task.
Little evidence in support of AoA affecting responses on semantic classification tasks (e.g. Morrison et al., 1992; Moore, 2003).
An AoA effect is not predicted by the phonological completeness hypothesis (Brown & Watson, 1987) nor the ‘phonological mapping’ hypothesis (Ellis & Lambon Ralph, 2000).

14. The Experiment. To investigate:
whether effects of AoA the same across stimulus types (objects vs. people).
whether effects of AoA the same across stimulus formats (pictures/faces vs. names).
influence of AoA on naming and semantic classification tasks.
Therefore, the experiment includes names, faces, and pictures and requires naming or semantic classification responses (are stimuli associated with the indoors or the outdoors?).

15. Method: Participants. 96 students and staff (53 female, 43 male).
Mean age = years, SD = 3.76, range years.
Divided equally between four conditions.

16. Method: Design I. Four major independent variables to the experiment:
Type of stimulus: objects vs. people.
Format of stimulus: pictures/faces vs. names.
Task: naming vs. semantic classification.
Age of Acquisition.
A 2 x 2 x 2 x 2 factorial design.
Between-participant factors: Task (naming vs. classification) and mode of presentation Format (words vs. pictures).
Within-participant factors: Stimulus (celebrity vs. object) and AoA (early vs. late).

17. Design: Experimental Conditions.
Condition 1: Reading names and words.
Condition 2: Semantic decision to names and words.
Condition 3: Naming faces and pictures of objects.
Condition 4: Semantic decision to faces and pictures of objects.
Order of presentation counterbalanced fully within each condition.
N = 24 per condition.

18. Method: Materials I. 80 critical stimuli (40 celebrities, 40 objects).
Foils comprised 50% of stimuli presented.
Grouped according to rated AoA.
Celebrity stimuli matched for number of syllables, familiarity and distinctiveness.
Object stimuli matched for visual complexity, word frequency, number of syllables, name agreement. Taken from Rossion and Pourtois’ (2001) set of Snodgrass and Vanderwart-like pictures.

19. Method: Materials II. E-Prime experiment generator.
Naming responses collected using a voice key. Errors recorded by experimenter using keyboard.
Classification responses recorded using a push button response box.

20. Method: Procedure. Conditions 1 and 2 used printed words.
Conditions 3 and 4 used 256x256 pixel greyscale images.
A short practice preceded each experiment.
Foils comprised 50% of the stimuli presented.

21. Method: Ratings Scales I.
Participants rated stimuli for AoA, familiarity, and, in the case of celebrities, facial distinctiveness (Moore & Valentine, 1998).
7-point scales for each variable.
AoA: 1 = unknown, 2 = under 3 years old, then up in multiples of 3 years to 7 = over 18 years old.
Familiarity: 1 = unknown, 7 = very familiar.
Distinctiveness: 1 = typical, 7 = highly distinctive.

22. Method: Ratings Scales II.
AoA: estimate when "first became aware...." of each stimulus.
Familiarity: estimate how many times, prior to the experiment, each stimulus had been encountered by the participant in everyday life, TV, films, newspapers, magazines, posters, etc.
Distinctiveness (celebrities only): estimate how easy to spot on crowded railway platform on facial features alone.

23. Results I: Main Effects.
AoA: early faster than late.
F(1,92)=188.15, p<.001.
Stimulus type: objects faster than celebrities.
F(1,92)=15.26, p<.001.
Task: naming faster than classification.
F(1,92)=17.67, p<.001.
Stimulus format: words faster than pictures.
F(1,92)=118.08, p<.001.

24. Results II: Interactions.
AoA x task: naming faster than classification.
F(1,92)=45.57, p<.001.
AoA x format: names faster than pictures.
F(1,92)=69.12, p<.001.
AoA x format x task:
F(1,92)=70.73, p<.001.
Type x format:
F(1,92)=7.46 p<.008.
Task x format:
F(1,92)=125.26, p<.001.

25. Post Hoc Ratings Results: Objects.
Early AoA
Late AoA
Sig.
Familiarity
6.12
5.85
0.101
AoA
2.71
3.37
< 0.001

26. Post Hoc Ratings Results: Celebrities.
Early AoA
Late AoA
Sig.
Familiarity
4.66
4.69
0.840
Distinctiveness
4.97
4.73
0.188
AoA
4.32
6.17
< 0.001

27. Conclusions I. Major findings:
AoA - participants responded to early-acquired stimuli faster than late-acquired stimuli across the board.
Task - Participants faster at naming than classifying same stimuli.
Stimulus type - participants responded to object faster than to celebrity stimuli.
Stimulus format - participants faster to respond to words than to pictures, but faster to respond to object pictures than celebrity pictures.

28. Conclusions II.
Main effect of early-acquired stimuli across all conditions.
Other findings consistent with previous literature:
response latencies to objects faster than to celebrities.
words processed faster than pictures.

29. Conclusions III.
Equivalence of magnitude of AoA effect does not fit easily with arbitrary mapping hypothesis (Zevin & Seidenberg, 2002) or phonological mapping.
Most readily explained by a multiple loci hypothesis, the SSPS (Set-up of a Specialised Processing System) hypothesis of Moore (In press).

30. Contact Details. Dr Viv Moore, Department of Psychology,
Keynes College,
University of Kent,
Canterbury,
Kent,
CT2 7NP.