Do birds (pigeons and bantams) know how confident they are of their perceptual decisions?

Rhesus monkeys are known to recognize confidence about their immediate perceptual and cognitive decisions by using a betting procedure (Son and Kornell in The missing link in cognition: origins of self-reflective consciousness. Oxford University Press, New York, pp 296–320, 2005; Kornell et al. in Psychol Sci 18:64–71, 2007). In this report, we examined whether this ability is shared in two avian species (pigeons and bantams) in order to know how widespread this metacognitive ability is among animals. We trained pigeons and bantams to search for a differently colored disk (target) among others (distracters) displayed on a touch-sensitive monitor. In test, the subjects were required to choose one of two confidence icons, “risk” and “safe”, after the visual search. A peck at the “risk” icon after a correct response in the visual search (i.e., a peck at the target) was reinforced by food and light, while that after an incorrect response (i.e., a peck at a distracter) resulted in a timeout. A peck at the “safe” icon was always reinforced by food and light, or by light only, regardless of the visual search result. The percentages of “safe” choices after incorrect responses were higher than after correct responses in all six pigeons and two of three bantams. This behavior generalized to novel stimuli in some subjects, and even to a novel line-classification task in a pigeon. These results suggest that these two distantly related avian species have in common a metacognitive ability that allows them to recognize confidence about their immediate perceptual decisions.     

Effects of luminance contrast on color spreading and illusory contour in the neon color spreading effect

The present study examined whether color spreading and illusory contours in the neon color spreading effect of Ehrenstein figures are governed by different mechanisms. In the experiment, Ehrenstein figures with colored crosses inserted in the central gaps were used. There were three luminance conditions: the luminance of the Ehrenstein figures was lower than, the same as, or higher than the luminance of the background. In each condition, 16 trials (2 sets of instructions X 8 repetitions) were conducted in a random order. Subjects were required to adjust the luminance of the colored crosses according to one of the two sets of instruction given before each trial. One was to adjust the upper and lower thresholds in the luminance of the colored crosses such that their color was seen to spread out of the crosses. The other was to adjust the thresholds such that circular illusory contours were visible. It was found that illusory contours disappeared and the color spreading remained when the crosses and the Ehrenstein figures were in or nearly in isoluminance or when the Ehrenstein figures and the background were in isoluminance. These results suggest that color spreading and illusory contours are governed by different mechanisms.     

Texture and motion spreading,the aperture problem,and transparency

When a cross of either static or moving texture is inserted in the intersection of an Ehrenstein figure, we find that the texture and its motion appear to spread outside of the cross. We suggest that these phenomena are analogous to neon color spreading, wherein an interpretation of a transparent surface makes the properties of that surface, which are physically visible only inside the cross, appear to spread over its apparent extent. In our experiments, the texture and the motion of the cross are attributed to the transparent surface. In addition, the spreading changes the apparent aperture within which the texture and its motion are seen, leading to a corresponding change in the apparent direction of motion.     

Planning over the day span: memory for the content of plans

The purpose of this study was to clarify the effect of the time of day on memory for the content of plans, and to examine the influence of knowledge of daily activities on it. Twenty‐four undergraduates participated as subjects in the experiment. Participants were told to memorize 24 plans of one day (e.g. ‘13:00’, ‘making a telephone call’), and were then asked to recall them in the test phase. Furthermore, we tried to explore their knowledge of everyday activities using a questionnaire. The result showed that plans of night, morning, and evening were recalled better than that of afternoon. This result was explained by the notion that knowledge of one's personal daily activities might affect memory of plans. Copyright © 2002 John Wiley & Sons, Ltd.     

The type A behavior pattern and immune reactivity to brief stress: change of volume of secretory immunoglobulin A in saliva

This article presents findings of a laboratory experiment on the association of the Type A behavior pattern with reactivity of secretory immune functioning to brief stress. 38 female undergraduate students classified as Type A (n = 19) or as Type B (n = 19) on the basis of their scores on the Kwansei Gakuin Type A scale performed a continuous arithmetic task in a situation in which they were exposed to aversive loud noise. Secretory immunoglobulin A (s-IgA) in saliva and autonomic measures (heart rate and frequency of eyeblink) were evaluated before and after the manipulation of stress. The volume of s-IgA at baseline was significantly higher for the Type A group than for the Type B group, suggesting that the former relative to the latter might be chronically higher in mucosal immune functioning. Also, the volume of s-IgA significantly increased after exposure to a brief stress for the Type B group but did not change for the Type A group, a finding which might indicate that the Type A group may have less immune reactivity to a brief stress.     

Representation of plans: activation in memory

The purpose of this study is to examine the temporal representation of plans in memory. Two experiments using a priming paradigm were conducted to investigate which plans would be activated in memory when participants processed a particular plan. The 64 undergraduates who participated in Experiment 1 were asked to memorise a 1-month schedule of plans. Results showed that when participants were presented with a particular plan as a prime, the preceding plan in the schedule was immediately activated. After the activation of the preceding plan, the plan following the prime plan in the schedule was activated. Experiment 2 was conducted to examine whether the sequential effect found in Experiment 1 might be based on day order (e.g., plans for day 1, plans for day 2, etc.) or simple ordering of plans (e.g., plan 1, plan 2, etc.). However, in the results of Experiment 2, with 48 undergraduate participants, the dynamic transition in the activation of plans along the time course, seen in Experiment 1, was not observed.