Tuesday, 7 February 2017

UNI ESSAYS The effects of Age of Acquisition on recognising familiar faces.

Abstract

The age of acquisition effect states that people respond faster to words/objects they learnt at a younger age. The age of acquisition effect has been looked at from many perspectives, however, there is not much research with the age of acquisition effect on facial recognition. The idea being that faces we were exposed to at a younger age would be recalled quicker than those we were exposed to at a later age. The test consisted of 40 faces. 20 of these were ‘familiar’ faces in that they were celebrities one may recognise (10 of these would be early acquired and 10 late) and 20 faces that were ‘unfamiliar’. The participant was to respond via a computer with Y if they recognise the face and N if not. This was timed in milliseconds. The results of this experiment were similar to the results of other age of acquisition experiments where words/objects were tested. The faces acquired earlier were recognised faster than those acquired later.

Introduction 
In previous experiments, it has been shown that words acquired earlier in life are recalled easier than those acquired later.  The same principle applies to objects and images.
In 2005, Juhasz found that words and pictures acquired earlier in life are processed quicker and therefore easier to recall than those acquired later. 
In an experiment conducted in 1998, Moore and Valentine found similar results when they tested recognition of “celebrities”. Again, the names of those celebrities acquired earlier in life were easier and quicker to recall. This is different to the experiment outlined in this assignment as it focuses on naming celebrities as opposed to recognising faces.
In 2004, Moore, Smith-Spark and Valentine conducted 2 experiments on the ‘Effects of age of acquisition on object perception’. In the first experiment, there were 39 participants (26 female & 13 male with a mean age of 28.33 (SD = 10.04) ). The participants were presented with stimuli (48 pictures from Snodgrass & Vanderwart 1980) and were encouraged to make fast responses. 24 of the pictures were early acquired and 24 were late acquired. The participants had to decide whether the images were of real objects or not. The real objects were recognised faster (mean = 568 ms, SEM = 5.38) than the non-objects (mean = 694ms, SEM = 5.90). Furthermore, the participants recognised the early acquired objects significantly faster than the late acquired objects. There was a lot of focus on answering fast in the experiment which may have impeded their accuracy.
In the second experiment, there were 38 participants (33 female, 5 male; mean age = 20.75 years, SD = 4.82). The stimuli presented were the same as those in the first experiment however they were regrouped into sets with high or low frequency names. There were 48 real objects and 48 non objects. The participants were significantly faster at recognising the pictures of objects with low frequency names (mean = 532ms SEM =3.21) than they were at recognising the pictures of objects with high frequency names (mean = 555ms, SEM = 3.55). The results were not as they had expected in this second experiment. 
The experimenters had fully expected the results of the first experiment however, the results of the second experiment came as a surprise as it was hypothesised that the high frequency words would have been recalled faster and more accurate than the low frequency words. This shows the significance of the effect of Age of Acquisition.
The aim of this particular experiment was to see if the same hypothesis could apply to facial recognition. 

Method

Participants
The participants were all undergraduate students enrolled in a Research Methods class. 104 participants took part in this experiment, 68 female and 34 male. 2 of the participants did not disclose their gender. 77 of the participants were UK students and 25 were international students. 2 participants did not disclose this information. The mean age of the participants was 25.36 years (SD = 8.95) and the range was 36.

Materials
The experiment was conducted using the experiment generator software programme, Superlab (Cedrus Corporation), which records reaction time to each stimulus (ms) on an IBM compatible computer. The images presented were all in greyscale and measured 256x256 pixels. Participants were told to type Y if they recognised the faces and N if not.

  
Design
The experiment was a ‘within subject’ design as all of the participants took part in both conditions of the experiment.  The independent variable was the Age of Acquisition, the dependant variable was the reaction time measured in milliseconds and the levels of treatment were early acquisition and late acquisition. Each image was presented with no apparent order with no clear pattern (e.g not MFMFMF or ELELEL etc). Once the participant had responded to one image the next image appeared immediately.

Procedure
Participants were shown to the experiment lab in the psychology department of London South Bank University.  Each participant had access to a computer and were asked to enter their gender, student ID, initials and whether they were a home or international student. Participants were then able to do a trail-run of the experiment beforehand which consisted of 6 images in the same format as the actual experiment in order that they were familiar with the procedure being used. The experiment itself consisted of 40 images and the participants were instructed to press Y if they recognised the face and N if they didn’t. Reaction time (ms) was recorded by the software programme. The image would remain on the screen until such a time when the participant responded with Y or N and then the next image followed immediately after. Once the test was finished the students were told to return to their normal classrooms.
  

Results
The results showed that faces acquired earlier in life had a quicker reaction time (mean = 929.61, SD = 355.23) than those acquired later (mean = 1013.89, SD = 373.44).
It is clear from these results that early acquired faces were recalled faster than both late acquired and also unfamiliar faces.
Discussion
The results of this experiment follow a similar pattern to the results of other Age of Acquisition experiments in that the earlier acquired faces were recognised faster and with greater accuracy than the later acquired faces. This supports the hypothesis proposed for this experiment.
Despite the accuracy of the hypothesis for this experiment, there are some problems with this method. Not everyone is exposed to the same faces at the same age. Faces that are early acquired for someone in their 40s may be late acquired for someone in their 20s. Similarly, someone in their 20s may acquire some faces earlier than someone in their 40s. Furthermore, some participants may not be aware that they have been exposed to certain faces and therefore may not recognise them. There is also a cultural issue with this experiment. In some cultures, people may be exposed to certain faces earlier or later than people in other cultures.

References 

Juhasz, BJ. (2005) Age of Acquisition effects in word and picture identification. Massachusetts: American Psychological Association.
Moore, V. & Valentine. T. (1998) The effect of age of acquisition on speed and accuracy of naming famous faces. United Kingdon: Taylor & Francis.
Moore, V., Smith-Spark, J. & Valentine, J. (2004) The effects of age of acquisition on object perception. European Journal of Cognitive Psychology.

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