Simultaneous presentation of similar stimuli produces perceptual learning in human picture processing

Human participants received unsupervised exposure to difficult-to-discriminate stimuli (e.g., A and A'), created with a morphing procedure from photographs of faces, before learning a discrimination between them. Experiments 1 and 2 demonstrated that prior exposure enhanced later discrimination and that intermixed exposure (A, A', A, A'...) resulted in better subsequent discrimination than blocked exposure (B, B, ...B', B'...). Experiments 3 and 4 showed that simultaneous exposure to 2 similar stimuli facilitated the later acquisition of both a simultaneous and a successive discrimination, and this effect was observed even though simultaneous exposure to 2 stimuli fostered the development of an excitatory association between them (Experiment 5). The findings of Experiments 1 and 2 revealed a perceptual learning effect with pictures of faces, and the findings of Experiments 3-5 are difficult to reconcile with associative analyses of perceptual learning.     

Class Size and Student Achievement

Contents:
Introduction, p.1
Quasi-Experimental Studies, p.3
Experimental and Quasi-Experimental Studies, p.15
Why Does Class Size Matter? Inferences from Existing Research, p.20
Implications of the Class-Size Findings, p.25
References, p.26
Appendix, p.29     

Perceiving affect from the voice and the face

This experiment examines how emotion is perceived by using facial and vocal cues of a speaker. Three levels of facial affect were presented using a computer-generated face. Three levels of vocal affect were obtained by recording the voice of a male amateur actor who spoke a semantically neutral word in different simulated emotional states. These two independent variables were presented to subjects in all possible permutations—visual cues alone, vocal cues alone, and visual and vocal cues together—which gave a total set of 15 stimuli. The subjects were asked to judge the emotion of the stimuli in a two-alternative forced choice task (either HAPPY or ANGRY). The results indicate that subjects evaluate and integrate information from both modalities to perceive emotion. The influence of one modality was greater to the extent that the other was ambiguous (neutral). The fuzzy logical model of perception (FLMP) fit the judgments significantly better than an additive model, which weakens theories based on an additive combination of modalities, categorical perception, and influence from only a single modality.     

Perceiving speech from inverted faces

We examined whether the orientation of the face influences speech perception in face-to-face communication. Participants identified auditory syllables, visible syllables, and bimodal syllables presented in an expanded factorial design. The syllables were /ba/, /va/, /δa/, or /da/. The auditory syllables were taken from natural speech whereas the visible syllables were produced by computer animation of a realistic talking face. The animated face was presented either as viewed in normal upright orientation or inverted orientation (180° frontal rotation). The central intent of the study was to determine if an inverted view of the face would change the nature of processing bimodal speech or simply influence the information available in visible speech. The results with both the upright and inverted face views were adequately described by the fuzzy logical model of perception (FLMP). The observed differences in the FLMP’s parameter values corresponding to the visual information indicate that inverting the view of the face influences the amount of visible information but does not change the nature of the information processing in bimodal speech perception     

Clinical,developmental and social aspects of infant crying and colic

Persistent unexplained infant crying in the first few months is a common source of distress for parents and is costly for the health services. The aim was to assess the merits of developmental and social conceptualizations of this phenomenon, compared to the clinical approach as represented by the concept of colic. From a community sample of 530 infants, 67 who met the ‘rule of threes’ definition of colic by fussing and crying for 3 or more hours per day at 4-5 weeks of age were chosen. To avoid confusion, these infants were called ‘persistent criers’. Groups of ‘evening criers’ (N = 38) and ‘moderate cries’ (N = 55) were also selected. These 160 infants were assessed by researcher measures of their consolability and by maternal diary measures of their amounts of fussing, crying and colic behaviour when 5-6 weeks old. The persistent and evening criers cried more than the moderate criers. However, irritable, ‘fussy’ behaviour was the predominant form of distress for all three groups of infants. Colic bouts–defined as ‘bouts of intense, unsoothable crying and other behaviour, perhaps due to stomach or bowel pain’–were rare even among the persistent criers and only 7% of these infants were found to be inconsolable. The results support growing evidence that normal infant developmental processes are central to this phenomenon. In addition, social interactions between infants and parents, and parental subjective variables, appear to be involved. Colic was distinguished as a rare and separate form of distress by the infants' mothers. Further evidence needs to determine whether colic is a distinct clinical phenomenon or an extreme degree of normal distress interpreted within a western cultural framework.     

The perception of rotated shapes: A process analysis of shape constancy

Ss made objective shape judgments of circular objects rotated in depth to provide a process analysis of shape constancy. The significant finding was that task difficulty, as reflected by proportion errors and correct reaction times; increased with increases in rotation from the frontal-parallel plane. This effect was located at the perceptual encoding stage of the shape judgment process. It was demonstrated that, in contrast to true shape information, the time to interpret slant and two-dimensional projected shape information was not critically dependent on degree of rotation. These results and a number of other additional observations demonstrate that the invariance hypothesis does not provide a sufficient account of shape constancy. Although projected shape and’ slant judgments can be made easily, perception of true shape involves encoding a figure-ground relationship by a process that does not rely exclusively on the discrete values of projected shape and slant.