Four groups of Ss were exposed to a probability learning situation in which they guessed which of two stimuli would next appear. One set of stimuli contained angry and smiling faces, while the other or neutral set contained big and little kangaroos. When the input ratio was 70 per cent angry faces to 30 per cent smiling faces, Ss markedly underestimated the dominant input. When the ratio was reversed (70 per cent smiling, 30 per cent angry), expectancies for the dominant stimulus approximated objective input. Thus, relative preferences for the stimuli appeared to dictate expectations. Expectancy curves for the relatively neutral kangaroos fell between the curves for the affective stimuli. Considerable interindividual variability was found for affective expectancies. These individual differences were tentatively associated with personality differences.