Sensory memory consolidation observed: Increased specificity of detail over days

Memories are usually multidimensional, including contents such as sensory details, motivational state and emotional overtones. Memory contents generally change over time, most often reported as a loss in the specificity of detail. To study the temporal changes in the sensory contents of associative memory without motivational and emotional contents, we induced memory for acoustic frequency by pairing a tone with stimulation of the cholinergic nucleus basalis. Adult male rats were first tested for behavioral responses (disruption of ongoing respiration) to tones (1–15 kHz), yielding pre-training behavioral frequency generalization gradients (BFGG). They next received three days of training consisting of a conditioned stimulus (CS) tone (8.00 kHz, 70 dB, 2 s) either Paired (n = 5) or Unpaired (n = 5) with weak electrical stimulation (～48 μA) of the nucleus basalis (100 Hz, 0.2 s, co-terminating with CS offset). Testing for behavioral memory was performed by obtaining post-training BFGGs at two intervals, 24 and 96 h after training. At 24 h post-training, the Paired group exhibited associative behavioral memory manifested by significantly larger responses to tone than the Unpaired group. However, they exhibited no specificity in memory for the frequency of the tonal CS, as indexed by a flat BFGG. In contrast, after 96 h post-training the Paired group did exhibit specificity of memory as revealed by tuned BFGGs with a peak at the CS-band of frequencies. This increased detail of memory developed due to a loss of response to lower and higher frequency side-bands, without any change in the absolute magnitude of response to CS-band frequencies. These findings indicate that the sensory contents of associative memory can be revealed to become more specific, through temporal consolidation in the absence of non-sensory factors such as motivation and emotion.     

Behavioral memory induced by stimulation of the nucleus basalis: Effects of contingency reversal

Specific behavioral associative memory induced by stimulation of the cortically-projecting cholinergic nucleus basalis (NB) is dependent on intrinsic acetylcholine and shares with natural memory such features as associativity, specificity, rapid formation, consolidation and long-term retention. Herein, we examined extinction and the effects of stimulus pre-exposure. Two groups of adult male rats (n = 4 each) were first tested for behavioral responses (disruption of ongoing respiration) to tones (1–15 kHz), constituting a pre-training behavioral frequency generalization gradient (BFGG). They next received a first session of training, 200 trials of a tone (8.00 kHz, 70 dB, 2 s) either paired with electrical stimulation of the NB (100 Hz, 0.2 s, ～67 μA, NBstm) (group IP) or unpaired (group IU). Twenty-four hours later, they were tested for behavioral memory by obtaining post-training BFGGs. Then the contingencies were reversed yet another 24 h later; the IP group received tone and NBstm unpaired and the IU group received them paired. A final set of generalization gradients was obtained the next day. All stimuli were presented with subjects under state control indexed by regular respiration. Tested 24 h post-initial training, the IP group developed specific associative behavioral memory indicated by increased responses only to CS-band frequencies, while the IU group did not. After subsequent training with unpaired stimuli, the IP group exhibited experimental extinction. Furthermore, after initial exposure to the CS and NBstm unpaired, the IU group exhibited a tendency toward reduced conditioning to CS/NBstm pairing and a significant increase in latency of conditioned responses. The present findings provide additional support for the hypothesis that engagement of the NB is sufficient to induce natural associative memory and suggest that activation of the NB may be a normal component in the formation of natural associative memory.     

The perception of 3-D shape from shadows cast onto curved surfaces

In a natural environment, cast shadows abound. Objects cast shadows both upon themselves and upon background surfaces. Previous research on the perception of 3-D shape from cast shadows has only examined the informativeness of shadows cast upon flat background surfaces. In outdoor environments, however, background surfaces often possess significant curvature (large rocks, trees, hills, etc.), and this background curvature distorts the shape of cast shadows. The purpose of this study was to determine the extent to which observers can “discount” the distorting effects of curved background surfaces. In our experiments, observers viewed deforming or static shadows of naturally shaped objects, which were cast upon flat and curved background surfaces. The results showed that the discrimination of 3-D object shape from cast shadows was generally invariant over the distortions produced by hemispherical background surfaces. The observers often had difficulty, however, in identifying the shadows cast onto saddle-shaped background surfaces. The variations in curvature which occur in different directions on saddle-shaped background surfaces cause shadow distortions that lead to difficulties in object recognition and discrimination.     

Improving psychological adjustment following a first episode of psychosis: A randomised controlled trial of cognitive therapy to reduce post psychotic trauma symptoms

There are few evaluated psychological interventions or theoretical approaches which are specifically aimed at reducing problems related to adjustment and adaptation following a first episode of psychosis. The present study tests the efficacy of a form of CBT (Cognitive Recovery Intervention; CRI) in reducing trauma, depression and low self esteem following a first episode of psychosis, in a single-blind randomised controlled trial. A total of 66 patients who had recently experienced a first episode of psychosis were randomly assigned to CRI or treatment as usual (TAU) and followed up at 6 and 12 months. People receiving CRI tended to have lower levels of post-intervention trauma symptoms and demonstrated greater improvement than those receiving TAU alone. This was especially the case at 6 months for those with high pre-treatment levels of trauma. There was, however, no advantage for the CRI group with regards to reduced depression or improved self esteem. In conclusion, CRI appears to be an effective intervention to help young people adapt to the traumatic aspects of a first episode of psychosis although further evaluation in a larger study is warranted.     

A randomized pilot study of motivation enhancement therapy to increase utilization of cognitive–behavioral therapy for social anxiety

Despite the efficacy of cognitive–behavioral therapy (CBT), most socially anxious individuals do not seek treatment or seek treatment only after many years of suffering. This study evaluated the efficacy of a three-session motivation enhancement therapy (MET) designed to increase CBT utilization among socially anxious individuals. Twenty-seven non-treatment-seeking socially anxious individuals (92.6% met current DSM-IV criteria for social anxiety disorder) were randomly assigned to either MET for CBT (n = 12) or a control condition (n = 15). The primary outcome was attendance at first CBT appointment. Secondary outcomes included openness to therapist contact and willingness to schedule a CBT appointment. After the intervention, seven of the 12 (58.3%) participants in the MET condition attended a CBT appointment compared to two of 15 (13.3%) control participants. Eight of 11 (72.7%) participants in the MET condition indicated they would like a CBT therapist to contact them compared to four of 12 (33.3%) controls. Further, willingness to schedule a CBT appointment increased at a significantly greater rate in the MET condition. Results suggest MET for CBT may be a time-efficient means to increase CBT utilization among socially anxious individuals.     

Separation Anxiety,Perceived Controllability,and Homesickness1

The present study examined the multidimensional interactionism model of anxiety, stress, and coping by investigating trait separation anxiety, controllability, and homesickness in 152 university students living away from home. Participants completed measures of trait separation anxiety, state anxiety, perceived controllability of the situation, and homesickness. Correlational tests confirmed that trait separation anxiety and homesickness were associated. Also, low perceived controllability was associated with state anxiety and homesickness. Finally, tests of a mediational model confirmed that both perceived controllability of the situation and state anxiety are significant mediators of the association between trait separation anxiety and homesickness. The findings provide support for models of homesickness that focus on diminished sense of personal control and proximity to attachment figures.     

Political ideology, exploration of novel stimuli, and attitude formation

In this study, the relations among political ideology, exploratory behavior, and the formation of attitudes toward novel stimuli were explored. Participants played a computer game that required learning whether these stimuli produced positive or negative outcomes. Learning was dependent on participants’ decisions to sample novel stimuli and discover the associated valence. Political ideology correlated with exploration during the game, with conservatives sampling fewer targets than liberals. Moreover, more conservative individuals exhibited a stronger learning asymmetry, such that they learned negative stimuli better than positive. Mediational analyses revealed that the differences in learning were due to the extent of exploratory behavior during the game. Relative to liberals, politically conservative individuals pursued a more avoidant strategy to the game, which led to their development of a more pronounced valence asymmetry in learning and attitude formation.     

Solution Strategies and Achievement in Dutch Complex Arithmetic: Latent Variable Modeling of Change

In the Netherlands, national assessments at the end of primary school (Grade 6) show a decline of achievement on problems of complex or written arithmetic over the last two decades. The present study aims at contributing to an explanation of the large achievement decrease on complex division, by investigating the strategies students used in solving the division problems in the two most recent assessments carried out in 1997 and in 2004. The students’ strategies were classified into four categories. A data set resulted with two types of repeated observations within students: the nominal strategies and the dichotomous achievement scores (correct/incorrect) on the items administered.It is argued that latent variable modeling methodology is appropriate to analyze these data. First, latent class analyses with year of assessment as a covariate were carried out on the multivariate nominal strategy variables. Results showed a shift from application of the traditional long division algorithm in 1997, to the less accurate strategy of stating an answer without writing down any notes or calculations in 2004, especially for boys. Second, explanatory IRT analyses showed that the three main strategies were significantly less accurate in 2004 than they were in 1997.     

Perceptions of the organizational context and psychological contract breach: Assessing competing perspectives

This study examines how employees’ perceptions of specific features of the organizational context—organizational politics and procedural justice—are related to their evaluations of psychological contract breach and subsequent attitudes and behaviors. Across three studies, we examined the appropriateness of four models for describing relationships among the focal constructs. Results of these studies support (a) an environmental responsiveness model in which psychological contract breach mediates the effects of politics and justice on employee outcomes, and (b) a general fairness evaluation model where politics, justice, and psychological contract breach serve as indicators of a higher order factor that predicts employee attitudes and behavior. Implications and directions for future research are presented.