The dot-probe attention bias task as a method to assess psychological wellbeing after anesthesia: A study with adult female long-tailed macaques (Macaca fascicularis)

Understanding the impact routine research and laboratory procedures have on animals is crucial to improving their wellbeing and to the success and reproducibility of the research they are involved in. Cognitive measures of welfare offer insight into animals’ internal psychological state, but require validation. Attention bias - the tendency to attend to one type of information over another – is a cognitive phenomenon documented in humans and animals that is known to be modulated by affective state (i.e., emotions). Hence, changes in attention bias may offer researchers a deeper perspective of their animals’ psychological wellbeing. The dot-probe task is an established method for quantifying attention bias in humans (by measuring reaction time to a dot-probe replacing pairs of stimuli), but has yet to be validated in animals. We developed a dot-probe task for long-tailed macaques (Macaca fascicularis) to determine if the task can detect changes in attention bias following anesthesia, a context known to modulate attention and trigger physiological arousal in macaques. Our task included the following features: stimulus pairs of threatening and neutral facial expressions of conspecifics and their scrambled counterparts, two stimuli durations (100 and 1000 ms), and counterbalancing of the dot-probe’s position on the touchscreen (left, right) and location relative to the threatening stimulus. We tested eight group-housed adult females on different days relative to being anesthetized (baseline and one-, three-, seven-, and 14-days after). At baseline, monkeys were vigilant to threatening content when stimulus pairs were presented for 100 ms, but not 1000 ms. On the day immediately following anesthesia, we found evidence that attention bias changed to an avoidance of threatening content. Attention bias returned to threat vigilance by the third day post-anesthesia and remained so up to the last day of testing (14 days after anesthesia). We also found that attention bias was independent of the type of stimuli pair (i.e., whole face vs. scrambled counterparts), suggesting that the scrambled stimuli retained aspects of the original stimuli. Nevertheless, whole faces were more salient to the monkeys as responses to these trials were generally slower than to scrambled stimulus pairs. Overall, our study suggests it is feasible to detect changes in attention bias following anesthesia using the dot-probe task in non-human primates. Our results also reveal important aspects of stimulus preparation and experimental design.

Negation and the Brain

This chapter reports an investigation into possible brain bases for negation. It begins with a review of negation experiments that used behavioral studies (measuring Reaction Time—RT), and functional Magnetic Resonance Imaging (fMRI) experiments that sought to identify local activations that correlate with the presence of negation. The chapter dwells on a major methodological problem that permeates the experimental study of negation processing, and proposes a solution: instead of overt negation, we study expressions that contain a covert negation—expressions that are Downward Entailing (DE) as evinced by their ability to reverse inferences and license NPIs in their scope. DE operators are thus taken to contain a hidden, or covert, negation, and contrast with the Upward Entailing counterparts (few vs. many; less vs. more). The chapter reviews behavioral experiments in healthy adults that indicate that DE has a processing cost, and an fMRI study that finds a single brain location for this computation. These results serve as a basis for an experiment on individuals with Broca’s aphasia. Tests with DE and UE quantifiers with these patients resulted in a mixed picture, which is discussed and its implications are derived.

The Ability of Elite Table Tennis Players With Intellectual Disabilities to Adapt Their Service/Return

In this study the ability of elite table tennis players with intellectual disability (ID) to adapt their service/return to specific ball spin characteristics was investigated. This was done by examining the performance of 39 players with ID and a reference group of 8 players without ID on a standardized table tennis specific test battery. The battery included 16 sets of 15 identical serves that had to be returned to a fixed target, and two additional tests measuring reaction time and upper limb speed. A 2 × 4 ANOVA (with group and type of spin as independent variables) with repeated measurements (15 consecutive returns) supported the hypothesis that elite table tennis players with ID were significantly less proficient than their counterparts without ID, but both groups demonstrated a comparable progression in learning. Spearman correlation coefficients indicated a positive relationship between accuracy of return and upper limb speed (rho = 0.42: p < .05) and reaction time (rho = 0.41: p < .05), showing that these generic factors are useful in partially explaining skill variations in specific sports.

The Quick Step: A New Test for Measuring Reaction Time and Lateral Stepping Velocity

The Quick Step measures reaction time and lateral stepping velocity. Upon a visual cue, participants step to the side as quickly as possible. Instrumentation includes floor pads with pressure-sensitive switches and two timers. In all, 109 older adults who had experienced a recent fall, 46 older adult nonfallers, and 24 young adults volunteered for testing. Reliability for reaction time and stepping velocity was good to excellent (intraclass correlation = 0.69–0.85). Multivariate analysis of variance revealed a significant difference between groups, p < 0.01, but not between stepping directions, p = 0.62–0.72, for both reaction time and stepping velocity. Reaction times were different among the three groups, p < 0.01, with the young adults having the fastest times and the older adult fallers having the slowest times. Lateral stepping velocity was faster among the young adults than for the two older groups, p < 0.01, but did not differ between the older adults, p = 0.29. It is concluded that the Quick Step is a simple and reliable tool for determining reaction time and lateral stepping velocity, and that this test can be used to detect a significant difference in reaction time between older adult fallers and nonfallers.

Overt Visual Attention in Parkinson's Disease

The ability of Parkinsonian (PD) patients to control overt visual attention was investigated, by measuring reaction time to a visual stimulus presented at different distances (1.5 deg, 6 deg, and 12 deg) and directions (left or right) from a central fixation point. Prior to the onset of the target stimulus (a square), a cue stimulus appeared just above the fixation point. With equal probability, the arrow pointed to the left, or to the right, or was ambiguous (with two heads). On 20% of their presentations, the left and right arrows pointed in the direction opposite to where the target was to appear. Subjects were informed that 20% of cues would be misleading, and correcting lenses were used to optimise their visual acuity. In previous work with a similar paradigm, only one target eccentricity was used, and subjects were not refracted, leaving open the possibility that PD subjects had more difficulty in seeing the cues and targets. The eight PD subjects had longer reaction times than age-matched normal controls (and were relatively slower for the more eccentric targets), but made fewer errors in all conditions. In particular, they were more accurate than the controls on the presentations when the cue was misleading or ambiguous, suggesting that the PD group were ignoring the cue. It seems unlikely that the subjects discriminate the direction of the cues, given the use of optical correction, and they reported seeing the cues. Our data are consistent with those of other workers who have described a similar ‘disengagement of attention’ in PD (Clark et al, 1989 Neuropsychologia27 131 – 140) and attributed it to decreased catecholaminergic activity following destruction of midbrain structures (Wright et al, 1990 Neuropsychologia28 151 – 159).