Indicative conditionals,conditional probabilities,and the “defective truth-table”: A request for more experiments

While there is now considerable experimental evidence that, on the one hand, participants assign to the indicative conditional as probability the conditional probability of consequent given antecedent and, on the other, they assign to the indicative conditional the “defective truth-table” in which a conditional with false antecedent is deemed neither true nor false, these findings do not in themselves establish which multi-premise inferences involving conditionals participants endorse. A natural extension of the truth-table semantics pronounces as valid numerous inference patterns that do seem to be part of ordinary usage. However, coupled with something the probability account gives us—namely that when conditional-free ? entails conditional-free ψ, “if ? then ψ” is a trivial, uninformative truth—we have enough logic to derive the paradoxes of material implication. It thus becomes a matter of some urgency to determine which inference patterns involving indicative conditionals participants do endorse. Only thus will we be able to arrive at a realistic, systematic semantics for the indicative conditional.     

Now you see it,now you don't: Explaining inconsistent evidence on gender stereotyping of newborns

Parental gender‐stereotyped perceptions of newborns—particularly their physical characteristics—have been discussed as important determinants of sex role socialization from birth on. However, corresponding empirical evidence is inconclusive. We propose that inconsistent findings on gender‐correlated perceptions are due to whether or not actual physical differences between newborn girls and boys are properly (statistically or experimentally) taken into account. In our study, 55 mother–father pairs rated both their own and two unknown newborns, labeled either female or male. Although we successfully replicated the typical gender‐correlated perceptions of own newborns' physical characteristics, all effects were explainable by actual physical sex differences in length and weight at birth. Similarly, no gender‐specific rating differences emerged as a function of labeled gender of unknown children matched in actual physical characteristics. Altogether, the findings demonstrate the vital importance of considering existing sex differences between newborn girls and boys for drawing valid conclusions on gender stereotyping of newborns.     

Rhythmic organization of heart rate in breast-fed and bottle-fed newborn infants

Heart rates and behavioural states of 14 breast-fed and 14 bottlefed newborn infants were assessed every 30 seconds for 2 continuous hours. The 240 observations of heart rate were treated as time-series data and spectrum-analysed for behavioural rhythmicities. Of the 28 infants, 25 showed reliable cycles in heart rate; 22 of the 25 infants showed a dominant frequency with a 30–60 min periodicity, one that approximates the basic-rest activity cycle (BRAC). In addition to this basic cycle, additional higher frequency cycles in long-term heart rate variability were evident in the spectra of many infants. Breast-fed newborns had greater numbers of reliable cycles in heart rate than bottle-fed newborns. Further, breast-fed newborns had lower overall mean heart rates and lower mean heart rates in Quiet and Active Sleep states than bottle-fed newborns. Bottle-fed newborns were observed more often in Quiet Sleep than breast-fed newborns. Without knowledge of the specific mechanisms causing these behavioural differences, the results of this study suggest that the context in which breast-feeding occurs results in a more complex and energy-efficient pattern of behavioural organization than the context of bottle-feeding.