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\title[] % (optional, use only with long paper titles)
{Category discrimination by infants}

\subtitle {A talk on {\em Basic-level category discriminations by 7- and 9-months-old in an object examination task} by Denis Mareschal, Daisy Powell and Agnes Volein}

\author[] % (optional, use only with lots of authors)
{Andreas van Cranenburgh}

\institute[] % (optional, but mostly needed)
{Universiteit van Amsterdam}

\date[] % (optional)
{November 7th, 2007}

\subject{Talks}
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\begin{document}
\section{Title}
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\section{Abstract}
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{\bf Abstract} 
\begin{itemize}
\item Infants can separate cat and dog figures \medskip
\item Cats are easier to distinguish from dogs than vice versa \medskip 
\item Categories are based on feature distributions \medskip
\end{itemize}

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\section{Introduction}
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{\bf Introduction}
\bigskip

A basic-level category is maximally informative:

\begin{itemize}
\item most common attributes shared with its members \medskip
\item least attributes shared with other categories \medskip
\end{itemize}

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\bigskip
``Conceptual structure'' might be in place at birth

\bigskip

Open question: are initial concept broad and narrowed down gradually, or the other way around?

\bigskip

Some research claims the former; only after 11 months cats and dogs would be distinguished
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\newpage

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\bigskip

However, {\em preferential looking} methods suggest the contrary. (Eimas et al, 1994)

\bigskip

Infants are shown photos. On the basis of attention the category forming is revealed.

\begin{itemize}
\item According to research, 3- to 4- month-olds can discriminate between basic level objects
\item A catogory of cats excluded dogs birds, dogs, horses and tigers
\item Mammals were excluded from birds and fish
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\bigskip

Critics argue that visual preference says nothing about conceptual capabilities:

\begin{itemize}
\item perceiving is different from acting upon
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\bigskip

However, the paper to be discussed (Mareschal et al, 2002) argues that whether visual or tactile, {\em feature-based recognition occurs} 

\begin{itemize}
\item Discrimination seems to correlate with variability of stimuli
\item Cats and dogs are familiarized in separate experiments
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The experiments:

\begin{itemize}
\item Each experiment: 30 infants (7 and 9 month-old)
\item Experiment 1: 4 cats during familiarization
\item Experiment 2: 4 dogs during familiarization
\item Remaining figures presented in test trials \\ (more cats \& dogs, and an eagle)
\end{itemize}

During test trials, the examining times were measured. Longer means more novel.
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Analysis of data reveals these results for cats (experiment 1):
\begin{itemize}
\item Significant decrease in examination time between first and second trial
\item Examination times correlate negatively with similarity
\end{itemize}

Also, analyzing the figures and their features shows:
\begin{itemize}
\item Only external body features contribute to discrimination
\item ...whereas head and facial features do not contribute significantly to discrimination.
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Analysis of data reveals these results for dogs (experiment 2):
\begin{itemize}
\item First and second trial do not differ significantly
\item Category includes both dogs and cats, but excludes eagles
\end{itemize}

Also, analyzing the figures and their features shows:
\begin{itemize}
\item Facial features contribute to discrimination
\item ...whereas the other features do not contribute significantly to discrimination.
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\newpage
\section{Conclusion}
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{\bf Conclusion}
\begin{itemize}
\item Cats are `more similar' to dogs than vice versa (dogs subsume cats)
\item Children use bottom-up strategies for discrimination (hence the assymmetry)
\item ... unlike adults, who (presumably) use top-down approaches
\item Object-examination tasks do not necessarily require conceptual processing (alternative: feature distribution)
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\newpage
\section{Bibliography}
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{\bf Bibliography}
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\bibitem{Mareschal} 
	Denis Mareschal, Daisy Powell and Agnes Volein,
	\emph{Basic-level category discriminations by 7- and 9-months-old in an object examination task},
	Journal of Experimental Child Psychology, 86, 87-107 (2002).

\bibitem{Eimas}
	Peter D. Eimas, Pail C. Quinn and Pamela Cowan,
	\emph{Development of Exclusivity in Perceptually Based Categories of Young Infants},
	Journal of Experimental Child Psychology, 58, 418-431 (1994).

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