Hypotheses in perception: their development about unambiguous stimuli in the environment

A series of seven photographs which depict a real scene as it is approached by an observer were shown, in sequence, to ninety-six university students. The photographs were either projected colour transparencies or black-and-white prints. Two sixes of photographs were used in each set and the series was presented with or without the first photograph. In earlier studies in which blurred photographs were used as stimuli, observers were unsure about their hypotheses. That was not the case in this study. Although individual observers differed widely in their initial hypotheses, the initial photographs were not perceived as ambiguous. It required on average from 2.9 photographs (large, black-and-white, full series) to 4.5 photographs (small, colour, full series) for correct identification. In general, colour is a hindrance to correct identification. For the full series approximately three hypotheses are put forward before the scene is correctly identified.     

Isolating the contributions of familiarity and source information to item recognition: a time course analysis.

Recognition memory may be mediated by the retrieval of distinct types of information, notably, a general assessment of familiarity and the recovery of specific source information. A response-signal speed-accuracy trade-off variant of an exclusion procedure was used to isolate the retrieval time course for familiarity and source information. In 2 experiments, participants studied spoken and read lists (with various numbers of presentations) and then performed an exclusion task, judging an item as old only if it was in the heard list. Dual-process fits of the time course data indicated that familiarity information typically is retrieved before source information. The implications that these data have for models of recognition, including dual-process and global memory models, are discussed.     

The structure of emotion: An empirical comparison of six models

There are a number of conflicting approaches to the problem of the relationship between different emotions. One category of models focuses on the valence of emotional experience and typically reports evidence for dimensional approaches to emotion. A second category of models argues for the possibility of discrete basic emotions, but typically focuses on evidence from emotion systems other than conscious experience. In the present study, a list of emotion terms was drawn up that were derived conceptually from a set of basic emotions. A group of participants filled out a questionnaire that asked how much in general they experienced each of the emotions. A structural equation modelling approach was then used with the resultant dataset, an approach that permitted the comparison of six different models that ranged from the positive-negative affect models to models of discrete basic emotions. The analyses gave support for a set of five basic emotions but only when these were allowed to correlate with each other. Implications for theories of emotion are considered.     

Apparent reversal frequencies in squares and trapezia: the effect of invariant and variant information

Three studies of apparent reversals (ARs) in rotating rectangular and trapezoid arrays are reported, together with a mathematical analysis. Study 1 explores the effect of different degrees of outline suppression on the frequency and distribution of ARs in squares and trapezia. Study 2 examines how modifications in both types of array reduce AR frequency, demonstrates a manipulation whereby ARs in rotating squares are eliminated, and suggests that ARs in squares and trapezia are of different origins. In the mathematical analysis, an invariant characteristic of the transformations of rotating rectangles is reported, and from this a numerical index is developed that expresses the extent to which a rotating trapezium may appear to pause just before each point of oscillation. In study 3 it is shown that this measure is a better predictor of AR frequencies than the heuristic proposed by Braunstein.     

Apparent movement induced by afterimages

A small light source viewed in the dark through an afterimage produced by an electronic flash may appear to move along short random paths. Experiment 1 shows that this is not an instance of the autokinetic phenomenon, and experiment 2 shows that it is not related to the 'fluttering hearts' phenomenon. On the basis of experiments 1 and 3 it is concluded that small-scale ocular drifts, microsaccades, and possibly tremors cause the whole afterimage to move. The afterimage serves as a frame of reference and induces movement of the light source.