Consistency and evidence

Williamson (2000) appeals to considerations about when it is natural to say that a hypothesis is consistent with one’s evidence in order to motivate the claim that all and only knowledge is evidence. It is argued here that the relevant considerations do not support this claim, and in fact conflict with it.     

Smoking cessation among self-quitters.

We examined cessation among 630 smokers who quit abruptly on their own. Continuous, complete abstinence rates were 33% at 2 days, 24% at 7 days, 22% at 14 days, 19% at 1 month, 11% at 3 months, 8% at 6 months postcessation, and 3% at 6 months with biochemical verification. Slipping (smoking an average of less than 1 cigarette/day) was common (9% to 15% of subjects) and was a strong predictor of relapse; however, 23% of long-term abstainers slipped at some point. These results challenge beliefs that most smokers can initially stop smoking and that most relapse occurs later on postcessation.     

The perceived duration of gratings.

Since visible persistence of grating patterns increases with spatial frequency, it is often inferred that the perceived duration of a grating is also longer at higher spatial frequencies. However, other work has demonstrated that the perceived onset of a grating is also delayed at higher spatial frequencies. Thus it is impossible to infer the subjective duration from the results of visible persistence studies alone. In order to estimate perceived duration in the present study, reaction times (RTs) to grating onsets and offsets were measured for a range of spatial frequencies. The results indicate that although the perceived duration (ie the difference between offset and onset RTs) was consistently longer than the physical duration, the estimates of perceived duration did not vary with changes in spatial frequency. Differences between the present results and earlier findings are interpreted in the context of the different methods used to measure perceived offset.     

I’ll just watch: Do the pro-social effects of coordination really generalize to non-actors?

ABSTRACT

Moving in time together has been shown to cultivate pro-social effects in co-actors, such as cooperation and helping. But less is known about who these effects apply to – whether they are restricted only to co-actors, or whether they generalize to those not involved in the coordination. One difference between past work finding generalized vs. restricted effects is whether these “outsiders” were present for the coordination or not. The present study explores whether the pro-social effects of coordination are seen towards observers as well as co-actors, and whether the absence or presence of observers during the coordination is a determining factor. Results show that greater cooperation following coordination is only seen amongst co- actors, regardless of whether the observers were present during the task or not. Findings are discussed in the context of the literature and alternative explanations for research showing generalized effects are suggested.