Subjective motion and acceleration induced by the movement of the observer’s entire visual field

Three experiments were carried out to trace the developmental time course of apparent subjective rotation induced by rotating a tall striped drum around an observer. In Experiment 1, rotation of the drum led to increasingly frequent reports of subjective rotation over the first 30 sec of stimulation by the optokinetic stimulus, after which subjects experienced mostly apparent subjective rotation and a small amount of drum rotation. In Experiment 2, using a magnitude estimation technique to assess the speed of drum and subjective rotation, subjects reported subjective acceleration and drum deceleration of about the same magnitude over the first 30 sec of the 1-rain trial, followed by a steady level of subjective rotation with some residual drum movement. In Experiment 3, using three different drum speeds, it was found that the speed of steady-state rotation, as well as subjective acceleration and drum deceleration, are linear functions of the speed of the inducing stimulus. Implications of these observations towards the explanation of how we perceive a stable environment during locomotion are discussed.     

What types of reminiscence are associated with successful aging?

To resolve the controversy regarding the adaptive benefits of reminiscence, the study was conducted to investigate what types of reminiscence are associated with successful aging. On the basis of prior research and content analysis, 6 types of reminiscence were identified: integrative, instrumental, transmissive, narrative, escapist, and obsessive. Successful aging was operationally defined as higher than average ratings in mental and physical health and adjustment as determined by an interviewer and a panel of gerontological professionals. Reminiscence data were gathered from 88 men and women judged to be aging successfully and 83 men and women judged to be aging unsuccessfully. All subjects were between 65 and 95 years of age, with approximately half living in the community and half in institutions. As predicted, successful agers showed significantly more integrative and instrumental reminiscence but less obsessive reminiscence than their unsuccessful counterparts. Community dwellers also showed more instrumental and integrative reminiscence than institutionalized seniors showed. Thus, only certain types of reminiscence are beneficial.     

Do they ‘look’ different(ly)? Dynamic face recognition in Malaysians: Chinese,Malays and Indians compared

Previous cross-cultural eye-tracking studies examining face recognition discovered differences in the eye movement strategies that observers employ when perceiving faces. However, it is unclear (1) the degree to which this effect is fundamentally related to culture and (2) to what extent facial physiognomy can account for the differences in looking strategies when scanning own- and other-race faces. In the current study, Malay, Chinese and Indian young adults who live in the same multiracial country performed a modified yes/no recognition task. Participants' recognition accuracy and eye movements were recorded while viewing muted face videos of own- and other-race individuals. Behavioural results revealed a clear own-race advantage in recognition memory, and eye-tracking results showed that the three ethnic race groups adopted dissimilar fixation patterns when perceiving faces. Chinese participants preferentially attended more to the eyes than Indian participants did, while Indian participants made more and longer fixations on the nose than Malay participants did. In addition, we detected statistically significant, though subtle, differences in fixation patterns between the faces of the three races. These findings suggest that the racial differences in face-scanning patterns may be attributed both to culture and to variations in facial physiognomy between races.     

The influence of visual ability on learning and memory performance in 13 strains of mice

We calculated visual ability in 13 strains of mice (129SI/Sv1mJ, A/J, AKR/J, BALB/cByJ, C3H/HeJ, C57BL/6J, CAST/EiJ, DBA/2J, FVB/NJ, MOLF/EiJ, SJL/J, SM/J, and SPRET/EiJ) on visual detection, pattern discrimination, and visual acuity and tested these and other mice of the same strains in a behavioral test battery that evaluated visuo-spatial learning and memory, conditioned odor preference, and motor learning. Strain differences in visual acuity accounted for a significant proportion of the variance between strains in measures of learning and memory in the Morris water maze. Strain differences in motor learning performance were not influenced by visual ability. Conditioned odor preference was enhanced in mice with visual defects. These results indicate that visual ability must be accounted for when testing for strain differences in learning and memory in mice because differences in performance in many tasks may be due to visual deficits rather than differences in higher order cognitive functions. These results have significant implications for the search for the neural and genetic basis of learning and memory in mice.     

Reconsolidation and memory infidelity in Lymnaea

Lymnaea stagnalis were operantly conditioned to not perform aerial respiratory behaviour in a specific context (i.e. context-1). The memory for this learned response was reactivated 3 days later in context-1. During the 1 h reconsolidation period following memory reactivation, randomly picked snails were either maintained in context-1 or exposed to a new context (i.e. context-2). One hour later in the post-reconsolidation period, snails in context-1 were placed for 1 h in context-2 and vice-versa. In neither the hypoxic reconsolidation nor the post reconsolidation periods did snails receive a reinforcing stimulus when they opened their pneumostome. All snails were blindly tested for memory 24 h later period in context-2. Only those snails that had been exposed to context-2 during the reconsolidation period exhibited 'memory' for context-2. That is, memory infidelity was observed. Snails exposed to context-2 in only the post-reconsolidation period did not show memory for context-2. The immediate cooling of snails after their exposure to the new context in the reconsolidation period blocked the formation the implanted memory. Snails trained in context-1 and exposed to context-2 in the consolidation period only, also did not have memory for context-2. However, the memory for context-1 could still be recalled following successful implantation of the 'new' memory. All data presented here are consistent with the notion that during the reconsolidation process memory can be updated.     

Recognition of temporal patterns: from engineering to psychology and back again.

An overview is presented on research conducted in our lab to quantify the underlying principles behind the recognition of temporal patterns. We have been developing a theory based upon pattern matching and time-series analysis, which allows us to model and understand how humans recognize familiar patterns evolving over time and how performance degrades with noise. While our studies are primarily scientific in nature, the work has application beyond the elucidation of psychological and physiological mechanisms. We illustrate an application of these ideas to computer-based human identification through gait analysis. This study also illustrates a novel approach to interdisciplinary research by integrating experimental psychology with that of engineering design.     

Associated factors of post-stroke depression among Hong Kong Chinese: a longitudinal study

The aim of this study was to explore associated factors of post-stroke depression (PSD) among Chinese first-time stroke patients. A 6-month prospective design was adopted with data collected by face-to-face interviews and physical assessment at two observation time points: T1, within 48 h of admission to the rehabilitation hospitals and T2, 6 months after the first interview in the subject's current place of residence. The prevalence of PSD at T1 and T2 was found to be 69% and 48% respectively. Backward linear regression showed that five variables explained 55% of the variance of PSD at T2. Participants who had a higher level of depression at T2 tended to have a higher level of functional disability, less social companionship and poorer informational support. Those who had been homemaker at pre-morbid state and those who exhibited a higher level of depressive symptoms at T1 showed a higher level of depression at T2. The results of this study suggest that PSD could be a psychological condition arising from the disabling consequences and altered family roles caused by a stroke.     

Effects of rater goals on rating patterns: evidence from an experimental field study

The goal-based perspective of performance appraisals suggests that raters who pursue different goals give different performance ratings. Yet previous studies have not provided strong empirical evidence that there are different impacts of different goals on mean rating and discriminability, nor have they provided evidence of a goal-rating causality. The authors extend the literature by manipulating rater goals in the context of peer evaluations of graded group projects with a sample of 104 undergraduate students. They find that (a) pursuing a harmony goal increased mean rating and decreased discriminability, and (b) pursuing a fairness goal increased mean rating and decreased discriminability when the group projects had not ended and increased mean rating but did not change discriminability when the group projects had ended.     

Response latency of gerbils and hamsters to nuts flavoured with bitter-tasting substances

The unconditioned reactions of Mongolian gerbils to peanuts rolled in sucrose octa-acetate (SOA) or denatomium benzoate (Bitrex) were studied in Experiment 1. Although SOA evokes as high a bitterness rating among humans as quinine salts, the gerbils' latency to ingest a nut flavoured with the former was similar to that to an unflavoured nut. Their oral latency to a nut that was flavoured with Bitrex was longer than to either an unflavoured one or one flavoured with SOA. However, the fact that they ingested a nut flavoured with the “most bitter substance known to man” within 70 sec after contact is surprising. Experiment 2 dealt with the effects of a peanut that was either unflavoured or flavoured with SOA or quinine and then paired with a LiCl injection. The oral latency of these gerbils to a nut conveying such flavours was assessed for six days after this conditioning. A nut flavoured with quinine acquired aversive properties but not ones that were flavoured with SOA or were unflavoured. Similar results were observed in Experiment 3, when hamsters were tested under comparable conditions. The theoretical implications of these results are discussed.