Category learning and multiple memory systems

Categorization is a vitally important skill that people use every day. Early theories of category learning assumed a single learning system, but recent evidence suggests that human category learning may depend on many of the major memory systems that have been hypothesized by memory researchers. As different memory systems flourish under different conditions, an understanding of how categorization uses available memory systems will improve our understanding of a basic human skill, lead to better insights into the cognitive changes that result from a variety of neurological disorders, and suggest improvements in training procedures for complex categorization tasks.     

Successive reversal of concurrent discriminations by macaques (Macaca mulatta): proactive interference effects

Rhesus monkeys received concurrent within-session training on eight, two-choice object pairs and then underwent successive reversals of these problems. Initially, reversals required about six times more training than acquisition with no improvement over seven successive reversals. Surprisingly, performance on these eight problems was unimpaired if they were embedded in different eight-problem tasks, thereby indicating a release from proactive interference. When the original eight problems again underwent successive reversal, no improvement was seen over seven reversals, although there was significantly less error-per-reversal than in the initial test. Subsequently, monkeys appeared to be developing a learning set for successive reversal because performance on successive reversal of eight novel problems was not different from that seen with the old familiar task. Set acquisition was confirmed when proficient reversal was eventually achieved on both old and new concurrent tasks. Thus, concurrent reversal set did develop, but it required arduous training to overcome proactive interference effects on memory. The ubiquitous influence of measurement context on organization of monkey memory was noted.     

Women's exposure to thin-and-beautiful media images: body image effects of media-ideal internalization and impact-reduction interventions

Exposure to media images of thin-and-beautiful women negatively affects the body image and mood states of young women. However, not all women are equally susceptible to these effects. The present experimental investigation with 123 young college women evaluated the moderating effects of the extent of internalization of media ideals. It also examined the preventative impact of two brief interventions (i.e., media literacy information with and without a dissonance-induction procedure). Results indicated that relative to a control group, the exposure to thin-and-beautiful media images adversely influenced the state body image of participants with high internalization levels. Media-literacy psychoeducation prior to the media exposure prevented this adverse effect. Adding a pre-exposure dissonance-induction procedure did not significantly enhance the preventative effects relative to psychoeducation alone. These results and their implications for the treatment and prevention of body image disturbances are discussed in the context of the empirical literature on the media's effects on body image.     

A blank look in reading: the effect of blank space on the identification of letters and words during reading

Two experiments investigated the effect of visual blank space on reading by varying the amount of interletter and interline blank space in prose passages. Increasing interletter blank spacing slowed the reading process overall, presumably because it disrupted the unitization of words and word identification, but it also improved the identification of the letters within words. By contrast, increasing interline blank spacing sped up the reading process overall, while also improving the identification of words and the letters within words, presumably because the extra spacing reduced the amount of visual information that was processed during reading. The latter finding supports the conclusion that information from surrounding lines of single-spaced text may interfere with reading.     

A study of 60- to 89-mo.-old children's skill at writing numerals

The skill of writing numerals necessitates a certain developmental maturity. Studying the age at which children start to develop this skill and assessing problems they encounter while writing numerals should give direction to their training. From 8 schools a total of 267 children, ages 60 to 89 mo., were asked to write the numerals 1 to 9. Analysis showed that 80% of the children wrote most of the numerals correctly, 15% wrote inverted numerals, 2.0% wrote some numerals as letters, and 4% did not write certain numerals at all. In addition, 64% of children ages 60 to 65 mo. gave correct responses, and the perception of correct responses increased across age groups until 95% were correct in the group who were 84 to 89 mo. There was no significant difference between girls and boys in these writing skills.     

Associative interference in recognition memory: A dual-process account

Associative interference from overlapping word pairs (A-B, A-D) reduces recall but has inconsistent effects on recognition. A dual-process account suggests that interference conditions reduce recollection but increase familiarity. This is predicted to increase recognition false alarms but have variable effects on recognition hits, depending on the relative contribution of recollection and familiarity. In three experiments that varied materials (sentences or random nouns) and test type (associative or pair recognition), interference conditions always increased recognition false alarms, but sometimes increased and sometimes decreased recognition hits. However, remember hits always decreased and know hits always increased with interference, patterns predicted of the recollection and familiarity processes, respectively. According to the dual-process view, a manipulation that affects the component processes in opposite ways can produce inconsistent patterns of recognition performance as the relative contribution of recollection and familiarity changes across tasks.     

Measuring Impulsivity in School-Aged Boys and Examining Its Relationship with ADHD and ODD Ratings

Seven different laboratory measures of impulsivity were administered to a group of 165 school-aged boys. Parents' and teachers' ratings of Attention Deficit and Hyperactivity Disorder and Oppositional/Defiant Disorder were also obtained. Factor analyses of impulsivity measures revealed the existence of a strong Inhibitory Control Factor including measures derived from Stop Task, the Continuous Performance Test, the Matching Familiar Figures Test, and the Circle Tracing Task. Other forms of impulsivity like resistance to interference, the Wisconsin Card Sorting Test and efficiency in the DRL Task loaded on a second independent factor. The Inhibitory Control factor was correlated with ADHD ratings, whereas the second factor was slightly related to the presence of ODD symptoms. Discussion is focused on the relevance of inhibitory control in impulsivity and ADHD research.     

Playboy Playmate curves: changes in facial and body feature preferences across social and economic conditions

Past research has investigated ideals of beauty and how these ideals have changed across time. In the current study, facial and body characteristics of Playboy Playmates of the Year from 1960-2000 were identified and investigated to explore their relationships with U.S. social and economic factors. Playmate of the Year age, body feature measures, and facial feature measurements were correlated with a general measure of social and economic hard times. Consistent with Environmental Security Hypothesis predictions, when social and economic conditions were difficult, older, heavier, taller Playboy Playmates of the Year with larger waists, smaller eyes, larger waist-to-hip ratios, smaller bust-to-waist ratios, and smaller body mass index values were selected. These results suggest that environmental security may influence perceptions and preferences for women with certain body and facial features.     

Visual skills in airport-security screening

Abstract— An experiment examined visual performance in a simulated luggage-screening task. Observers participated in five sessions of a task requiring them to search for knives hidden in x-ray images of cluttered bags. Sensitivity and response times improved reliably as a result of practice. Eye movement data revealed that sensitivity increases were produced entirely by changes in observers' ability to recognize target objects, and not by changes in the effectiveness of visual scanning. Moreover, recognition skills were in part stimulus-specific, such that performance was degraded by the introduction of unfamiliar target objects. Implications for screener training are discussed.     

Strong memories obscure weak memories in associative recognition

The list strength effect, in which strengthening some memories has a detrimental effect on the retrieval of other memories, has generally not been found in item recognition. The present study shows that the list strength effect does occur in associative recognition. Study materials were sets of overlapping word pairs (A-B, A-C, D-B, etc.). Within critical sets of words, strong pairs were presented three times at study, as compared with one presentation for weak pairs. In Experiment 1, associative recognition for weak pairs was less accurate than that for baseline pairs, and response times for hits were slower. In Experiment 2, receiver-operating characteristic curve data provided further evidence of poor accuracy for weak pairs. These findings support a qualitative distinction between item and associative recognition.