Distinctiveness models of memory and absolute identification: evidence for local, not global, effects

Many models of memory assume that the probability of remembering an item is related to how distinctive that item is relative to all the other items in the set, with no distinction made between the contributions of near or far items. These “global” distinctiveness models do well in accounting for the ubiquitous serial position effects observed in numerous memory paradigms, including absolute identification. Here, we provide experimental confirmation of Bower's (1971) suggestion that, contrary to a fundamental prediction of global distinctiveness models, midseries items can be more discriminable than their immediate neighbours. We show that such data are consistent with a revised distinctiveness account in which the factor affecting discrimination performance is primarily the distinctiveness of an item relative to its close neighbours.     

Compatibility effects in stopping and response initiation in a continuous tracking task

Two experiments explored stopping performance using a new stimulus-response compatibility effect spanning action initiation and stopping. Participants tracked a sometimes-moving, sometimes-stationary target by controlling the speed of a response marker via a force sensor. In the compatible condition, participants pressed the sensor in response to the target moving and stopped pressing in response to the target stopping. In the incompatible condition, participants stopped pressing in response to the target moving and initiated pressing in response to the target stopping. Response initiation and stopping were found to be faster under compatible than under incompatible conditions, regardless of whether compatible and incompatible trials were blocked or mixed. These findings indicate that stopping, like response initiation, is influenced by stimulus-response properties such as compatibility. This in turn suggests that stopping is governed by constraints similar to those of other behaviours.     

Movement characteristics support a role for dead reckoning in organizing exploratory behavior

Rat exploration is an organized series of trips. Each exploratory trip involves an outward tour from the refuge followed by a return to the refuge. A tour consists of a sequence of progressions with variable direction and speed concatenated by stops, whereas the return consists of a single direct progression. We have argued that processing self-movement information generated on the tour allows a rat to plot the return to the refuge. This claim has been supported by observing consistent differences between tour and return segments independent of ambient cue availability; however, this distinction was based on differences in movement characteristics derived from multiple progressions and stops on the tour and the single progression on the return. The present study examines movement characteristics of the tour and return progressions under novel-dark and light conditions. Three novel characteristics of progressions were identified: (1) linear speeds and path curvature of exploratory trips are negatively correlated, (2) tour progression maximum linear speed and temporal pacing varies as a function of travel distance, and (3) return progression movement characteristics are qualitatively different from tour progressions of comparable length. These observations support a role for dead reckoning in organizing exploratory behavior.     

Assessment of quality of life in a multicultural cancer patient population

Quality of life (QOL) is increasingly assessed in cancer patients. In this article, the authors examined the psychometric performance of a commonly used QOL questionnaire, the Quality of Life Questionnaire--Cancer 30 (QLQ-C30; N. K. Aaronson et al., 1993), in multiethnic cancer patients. Content validation studies in patients and clinicians identified possible new items. Multiple-group confirmatory factor analysis supported equivalent structure across ethnic groups (Caucasians and Asian/Pacific Islanders [APIs]). A higher order QOL factor appeared to directly affect functioning scales and symptom count. Exploratory factor analysis examined effects of new items. Ten factors were extracted, 6 consistent with the original instrument and 4 reflecting potentially new aspects of QOL: Positive Social Support, Coping, Existential Well-Being, and Sexuality/Intimacy. The QLQ-C30 appears appropriate for use in API cancer patients. Further work needs to ensure that it includes all important domains.     

Behavioral activation and inhibition systems and the severity and course of depression

Theorists have proposed that depression is associated with abnormalities in the behavioral activation (BAS) and behavioral inhibition (BIS) systems. In particular, depressed individuals are hypothesized to exhibit deficient BAS and overactive BIS functioning. Self-reported levels of BAS and BIS were examined in 62 depressed participants and 27 nondepressed controls. Clinical functioning was assessed at intake and at 8-month follow-up. Relative to nondepressed controls, depressed participants reported lower BAS levels and higher BIS levels. Within the depressed group, lower BAS levels were associated with greater concurrent depression severity and predicted worse 8-month outcome. Levels of both BIS and BAS showed considerable stability over time and clinical state. Overall, results suggest that BAS dysregulation exacerbates the presentation and course of depressive illness.     

Acquisition of categorical color perception: a perceptual learning approach to the linguistic relativity hypothesis

Color perception can be categorical: Between-category discriminations are more accurate than equivalent within-category discriminations. The effects could be inherited, learned, or both. The authors provide evidence that supports the possibility of learned categorical perception (CP). Experiment 1 demonstrated that observers' color discrimination is flexible and improves through repeated practice. Experiment 2 demonstrated that category learning simulates effects of "natural" color categories on color discrimination. Experiment 3 investigated the time course of acquired CP. Experiment 4 found that CP effects are acquired through hue- and lightness-based category learning and obtained interesting data on the dimensional perception of color. The data are consistent with the possibility that language may shape color perception and suggest a plausible mechanism for the linguistic relativity hypothesis.     

Domain-specificity and theory of mind: evaluating neuropsychological evidence

Humans' unique aptitude for reasoning about mental states, known as Theory of Mind (ToM), can help explain the unique character of human communication and social interaction. ToM has been studied extensively in children, but there is no clear account of the cognitive basis of ToM in adults. Evidence from functional imaging and neuropsychology is beginning to address this surprising gap in our understanding, and this evidence is often thought to favour a domain-specific or modular architecture for ToM. We present a systematic approach to this issue for the paradigmatic case of belief reasoning, and argue that neuropsychological data provide no clear evidence for domain-specificity or modularity. Progress in understanding ToM requires new tasks that isolate potentially distinct components of this complex ability.     

Relating derived relations as a model of analogical reasoning: reaction times and event-related potentials

The current study aimed to test a Relational Frame Theory (RFT) model of analogical reasoning based on the relating of derived same and derived difference relations. Experiment 1 recorded reaction time measures of similar-similar (e.g., "apple is to orange as dog is to cat") versus different-different (e.g., "he is to his brother as chalk is to cheese") derived relational responding, in both speed-contingent and speed-noncontingent conditions. Experiment 2 examined the event-related potentials (ERPs) associated with these two response patterns. Both experiments showed similar-similar responding to be significantly faster than different-different responding. Experiment 2 revealed significant differences between the waveforms of the two response patterns in the left-hemispheric prefrontal regions; different-different waveforms were significantly more negative than similar-similar waveforms. The behavioral and neurophysiological data support the RFT prediction that, all things being equal, similar-similar responding is relationally "simpler" than, and functionally distinct from, different-different analogical responding. The ERP data were fully consistent with findings in the neurocognitive literature on analogy. These findings strengthen the validity of the RFT model of analogical reasoning and supplement the behavior-analytic approach to analogy based on the relating of derived relations.     

Distinctiveness and the recognition mirror effect: evidence for an item-based criterion placement heuristic

Superior detection and rejection of 1 versus another class of items during recognition is called the mirror effect. Some mirror effects may involve strategic criterion adjustments based on item distinctiveness and its relation to memorability. Three experiments demonstrated mirror effects for known versus unknown scenes and 1 suggested a similar pattern for faces. In opposition to preexperimental familiarity, lures from known and frequently encountered locations were confidently rejected more often than unknown lures. Forgetting and speeding recognition reversed this lure response pattern, suggesting abandonment of strategic adjustment in favor of a single fixed criterion. With sufficient response time and recent encoding, observers demand more evidence for conceptually distinctive items, perhaps because such items typically foster vivid recollection during retrieval.     

The effect of central and peripheral field stimulation on the rise time and gain of human optokinetic nystagmus

We wished to examine the spatial (gain) and temporal (rise time) properties of human optokinetic nystagmus (OKN) as a function of stimulus velocity and field location. Stimuli were either M-scaled random dots or vertical stripes that moved at velocities between 20-80 deg s(-1). Three field conditions were examined: full field; a 20 deg central field; and a 12.5 deg central-field mask. OKN gain was found to be significantly affected by stimulus velocity and stimulus location, with the higher stimulus velocities and the 12.5 deg central-field mask giving lower gains. Steady-state gains for all three field conditions were not found to be affected by prior adaptation to stationary or moving stimuli. The 63% rise time was found to be significantly affected by the stimulus velocity, whereas this was not the case for the 90% rise time. Neither rise time was found to be significantly affected by the field location. These results indicate that, although the effectiveness (gain) of peripheral retina is lower than that of the central retina during optokinetic stimulation, the peripheral retina has access to common mechanisms responsible for the fast component of OKN.