The Department of Cognitive Science cordially invites you to the public defense of the PhD thesis of
Primary supervisor: Christophe Heintz
Secondary supervisor: Dan Sperber
External advisor: OIivier Morin
Venue: Popper Room, Nador street 9.
Time: 2 pm
This thesis aims at developing a framework for empirical research in cultural evolution, drawing on cultural attraction theory. This framework is outlined in the Introduction. The five chapters of the thesis demonstrate the robustness of this framework across different cultural domains and diverse types of causal factors relevant to explaining the emergence, success, and evolution of cultural types.
Chapter 1 reviews the use of cultural transmission experiments (transmission chains, replacement, closed groups and seeded groups) in studying cumulative cultural evolution. Cumulative cultural evolution is usually defined as the process by which traditions are gradually modified. This chapter identifies several mismatches between theoretical definitions of cumulative culture and their implementation in cultural transmission experiments, and suggests possible solutions to reduce these mismatches.
Chapter 2 documents an exception to Zipf’s law of abbreviation (which relates more frequent signals to shorter signal lengths) by observing two large corpus of European heraldic motifs (total N = 25115). Our results suggest that lacking –or at least losing- iconicity may be a precondition for Zipf’s Law of Abbreviation to obtain in a graphic code.
Chapter 3 tests hypotheses on possible determinants of visual complexity in characters, using a standardized collection of 47,880 pictures from 133 writing systems, and two measures of visual complexity (algorithmic and perimetric). This chapter provides evidence that (1) the size of a script’s inventory influences character complexity, (2) one of the main determinant of character complexity is the script’s type (e.g., alphabetic, syllabic), and (3) there is a surprising lack of evolutionary change in character complexity.
Chapter 4 provides evidence of the existence of a forward bias in human profile-oriented portraits: there is a widespread tendency (total N = 1833, from 582 unique painters) to represent sitters with more space in front of them than behind them. It also suggests that this bias became more frequently and more strongly expressed over time.
Chapter 5 shows that different physical affordances can influence the rhythms naïve participants produce in a transmission chain experiment. Rhythmical sequences produced by participants having to adapt to use different movements reflected such constrains in both their structure and timing.
Two shorter introductions to chapter 2 and 3 and to chapter 4 and 5 outline the commonalities between the two chapters they each introduce. The conclusion revisits the question raised and the framework outlined in the introduction in the light of the five chapters of the thesis.