On the surprising salience of curvature in grouping by proximity

The authors conducted 3 experiments to explore the roles of curvature, density, and relative proximity in the perceptual organization of ambiguous dot patterns. To this end, they developed a new family of regular dot patterns that tend to be perceptually grouped into parallel contours, dot-sampled structured grids (DSGs). DSGs are similar to the dot lattices used to study grouping by proximity, except that only one of the potential organizations is rectilinear; the others are curvilinear. The authors used the method of M. Kubovy and J. Wagemans (1995) to study grouping by proximity in DSGs. They found that in the competition between the most likely organizations, one rectilinear and the other curvilinear, the latter is more salient. This phenomenon cannot be explained by contemporary accounts of grouping by proximity or contour integration.     

Rate of acquisition, adult age, and basic cognitive abilities predict forgetting: new views on a classic problem

Rate of forgetting is putatively invariant across individuals, sharing few associations with individual-differences variables known to influence encoding and retrieval. This classic topic in learning and memory was revisited using a novel statistical application, multilevel modeling, to examine whether (a) slopes of forgetting varied across individuals and (b) observed individual differences in forgetting shared systematic relations with adult age, learning speed, and cognitive ability. Participants (N = 136) received mnemonic training prior to memorizing 4-digit numbers to perfection, and retention was tested immediately after training and after 30 min, 24 hr, 7 weeks, and 8 months. Slower rate of learning to criterion, older age, and poorer cognitive performance predicted accelerated forgetting with associations most pronounced within 24 hr from baseline. Observed correlates of differential forgetting slopes are similar to those previously found to affect encoding, suggesting continuity rather than asymmetry of prediction for these memory processes.     

Stress modulates the use of spatial versus stimulus-response learning strategies in humans

Animal studies provided evidence that stress modulates multiple memory systems, favoring caudate nucleus-based "habit" memory over hippocampus-based "cognitive" memory. However, effects of stress on learning strategy and memory consolidation were not differentiated. We specifically address the effects of psychosocial stress on the applied learning strategy in humans. We designed a spatial learning task that allowed differentiating spatial from stimulus-response learning strategies during acquisition. In 13 subsequent trials, participants (88 male and female students) had to locate a "win" card out of four placed at a fixed location in a 3D model of a room. Relocating one cue in the last trial allowed inferring the applied learning strategy. Half of them participated first in the "Trier Social Stress Test." Salivary cortisol and heart rate measurements were taken. Stressed participants used a stimulus-response strategy significantly more often than controls. Subsequent verbal report revealed that spatial learners had a more complete awareness of response options than stimulus-response learners. Importantly, learning performance was not affected by stress. Taken together, stress prior to learning facilitated simple stimulus-response learning strategies in humans-at the expense of a more cognitive learning strategy. Depending on the context, we consider this as an adaptive response.     

Brain activation while forming memories of fearful and neutral faces in women and men

Event-related functional MRI (fMRI) was used to assess brain activity during encoding of fearful and neutral faces in 12 women and 12 men. In a subsequent memory analysis, the authors separated successful from unsuccessful encoding of both types of faces, based on whether they were remembered or forgotten in a later recognition memory test. Overall, women and men recruited overlapping neural circuitries. Both sexes activated right-sided medial-temporal regions during successful encoding of fearful faces. Successful encoding of neutral faces was associated with left-sided lateral prefrontal and right-sided superior frontal activation in both sexes. In women, relatively greater encoding related activity for neutral faces was seen in the superior parietal and parahippocampal cortices. By contrast, men activated the left and right superior/middle frontal cortex more than women during successful encoding of the same neutral faces. These findings suggest that women and men use similar neural networks to encode facial information, with only subtle sex differences observed for neutral faces.     

Coding counsellor behaviour in motivational interviewing sessions: inter-rater reliability for the Swedish Motivational Interviewing Treatment Integrity Code (MITI)

The aim of this study was to evaluate inter-rater reliability when using the Swedish version of the Motivational Interviewing Treatment Code (MITI) as an adjunct to MI training, clinical practice and research. Coders were trained to use the MITI for scoring taped sessions. The 4-month basic training had a duration of 39 hours. Following training, 60 audio-taped live interviews were randomly assigned for MITI coding. Mean intra-class correlation (ICC) coefficients were calculated for 7 coders across all pairs of coders. Cronbach's alpha was calculated to estimate the covariance between each pair across their common interviews. Six months later, a second inter-rater reliability test was performed, when 5 coders coded the same 15 randomly selected tapes. At the second reliability testing the mean ICC was 0.81 and the mean Cronbach's alpha was 0.96. However, the ICC varied for different sub-variables of the MITI, ranging from 0.42 empathy to 0.79 for number of Closed questions. In conclusion, MITI shows promising potential to be a reliable tool to confirm and enhance MI training as well as practice in clinical settings and in evaluating MI integrity in clinical MI research. However, coder assessment of empathy and MI-spirit, "global" variables, requires further refinement.     

Timing matters: Temporal dynamics of stress effects on memory retrieval

Stress may impair memory retrieval. This retrieval impairment has been attributed to the action of the stress hormone cortisol, which is released with a delay of several minutes after a stressful encounter. Hence, most studies tested memory retrieval 20–30 min after stress, when the stress-induced cortisol increase peaks. In the present experiment, we investigated whether retrieval impairments can also be found at later intervals after stress. To this end, participants learned a list of words on day 1. Twenty-four hours later, they were first exposed to a stressor or a nonstressful control manipulation and completed a recognition test for the words either immediately thereafter, 25 min later, or 90 min later. Our findings showed that stress did not impair memory retrieval when memory was tested immediately after the stressor, before cortisol levels were elevated. However, retrieval performance was impaired 25 min after stress, when cortisol levels peaked, as well as 90 min after the stressor, when cortisol levels had already returned to baseline. The retrieval impairment 90 min after stress appeared to be even stronger than the one after 25 min. These findings suggest that the detrimental effects of stress on retrieval performance may last longer than is usually assumed.     

Effects of testing on subsequent re‐encoding and long‐term forgetting of action‐relevant materials: On the influence of recall type

Testing one's memory of previously studied information reduces the rate of forgetting, compared to restudy. However, little is known about how this direct testing effect applies to action phrases (e.g., “wash the car”) – a learning material relevant to everyday memory. As action phrases consist of two different components, a verb (e.g., “wash”) and a noun (e.g., “car”), testing can either be implemented as noun‐cued recall of verbs or verb‐cued recall of nouns, which may differently affect later memory performance. In the present study, we investigated the effect of testing for these two recall types, using verbally encoded action phrases as learning materials. Results showed that repeated study–test practice, compared to repeated study–restudy practice, decreased the forgetting rate across 1 week to a similar degree for both noun‐cued and verb‐cued recall types. However, noun‐cued recall of verbs initiated more new subsequent learning during the first restudy, compared to verb‐cued recall of nouns. The study provides evidence that testing has benefits on both subsequent restudy and long‐term retention of action‐relevant materials, but that these benefits are differently expressed with testing via noun‐cued versus verb‐cued recall.