with the notion that people have an intrinsic preference for reciprocity. There is little evidence that contestants' propensity to cooperate depends positively on the likelihood that their opponent will cooperate (i.e., they find little evidence for conditional cooperation). Young males are less cooperative than young females, but this gender effect reverses for older contestants since men become increasingly more cooperative as their age increases. Contestants that promised to split were more likely to split. Two evolutionary biologists, including Stuart West, have also analysed the correlates of decisions of the final contestants and found similar results. In addition, they also found the following: Contestants were less likely to split when their partner had previously lied about the value of their cash balls, but not to hide their killer balls. Contestants that initiated laughter were more likely to split. In contrast, contestants that initiated physical contact were less likely to split, and being touched was also correlated with being less likely to split. Another study focuses on whether it is possible to predict the behavior of contestants by carefully analyzing what they say. They find that contestants who make statements that carry an element of conditionality ("I will split if you split") or implicitness ("I want to split", "I came here to split") are less likely to cooperate than contestants who make more explicit promises ("I will split"). Reception The first show opened with 1.6 million viewers. Viewership climbed to a steady 2 million viewers. In the same 17:00 timeslot, eight of the first eleven episodes beat Channel 4's Richard & Judy, and The Weakest Link on BBC Two also took a dent from the show's success. Series 2 went on to average 2.1 million viewers in early 2008. As of summer 2009, the show's popularity fell; it attracted only around 1.2 million viewers, which led to the show's termination on 18 December 2009. It is still regularly shown throughout the week on Challenge in the UK and Republic of Ireland although usually during off-peak times. It is now also showing on ITV again but usually after midnight. British psychologist Adrian Raine criticised the show, arguing that it "encourages deceitfulness", and that many of its contestants are celebrated for displaying "characteristics of psychopathy". In a review of another ITV quiz show—The Colour of Money—Charlie Brooker criticised Golden Balls rules, saying that "[Golden Balls] has more rules and clauses than the European Convention