The rewarding effects of number and surface area of food in rats

Visual cues have an important role in food preference for both rats and humans. Here, we aim to isolate the effects of numerosity, density, and surface area on food preference and running speed in rats, by using a forced-choice maze paradigm. In Experiment 1, rats preferred and ran faster for a group of multiple smaller pellets rather than a single large pellet, corroborating previous research (Capaldi, Miller, & Alptekin Journal of Experimental Psychology: Animal Behavior Processes, 15(1), 75–80, 1989). Further experiments tested the prevailing hypothesis that multiple food pieces are more reinforcing because they occupy a larger surface area. Experiment 2 controlled for numerosity by utilizing a continuous food: mashed potatoes flattened to cover a larger surface area or rounded into a ball. The rats preferred and ran faster for the flattened potatoes, suggesting surface area plays a role in quantity estimations. Finally, in Experiment 3, rats displayed no preference or difference in running speed between a group of scattered and clustered pellets when number of pellets were kept constant. Taken together, these results suggest that density has an important role in food perception—that is, the rewarding effect of higher numerosity or larger surface area is removed when the food does not fill out the entire space. Alternative explanations and implications for human diet are discussed.     

文化与幼儿教育的北美视角:关注优质与独特

北美地区区域十分辽阔，有着多种化和种族群体。无论在现代化的美国本土，还是在寒冷的阿拉斯加和加拿大，或是在荒漠、炎热和潮湿的北美区域，都有我们早期教育的课堂。早期教育渗透在拥挤的都市，同时也深入到了偏远条件艰苦的地方。北美地区的幼儿教育，是差别很大的概念。     

Psychosocial correlates of child abuse potential in multiply disadvantaged adolescent mothers

OBJECTIVE: This study had two aims: First to examine psychosocial correlates of child maltreatment risk, and second to assess the validity of the CAP Inventory (Milner, 1986) with multiply disadvantaged teenage mothers. METHOD: Participants were 75 adolescent mothers who were wards of the Illinois child protection system. Mothers (aged 14-18) and infants participated in home-based psychosocial assessment of personal and parenting functioning. Group comparisons examined differences for mothers with elevated versus normal versus invalid CAP scores due to faking good. RESULTS: Findings indicated that abuse risk groups differed on emotional distress, social support satisfaction, reading achievement, and years of education, but not on parenting beliefs or quality of child stimulation. Differences favored the normal over the elevated risk group in all significant comparisons, whereas mothers with elevated faking good differed from normals only in lower reading achievement. Multiple regression analysis highlighted emotional distress, support dissatisfaction, and low achievement as significant predictors of greater abuse risk. CONCLUSIONS: Despite sharing multiple disadvantages, adolescent wards are a heterogeneous group who show different levels of psychosocial functioning corresponding to levels of child maltreatment risk. The findings provide support for the concurrent validity and clinical applicability of the CAP Inventory with disadvantaged teenage mothers.