Andy Skinner

Nine-Year-Old Children Use Norm-Based Coding to Visually Represent Facial Expression

Children are less skilled than adults at making judgments about facial expression. This could be because they have not yet developed adult-like mechanisms for visually representing faces. Adults are thought to represent faces in a multidimensional face-space, and have been shown to code the expression of a face relative to the norm or average face in face-space. Norm-based coding is economical and adaptive, and may be what makes adults more sensitive to facial expression than children. This study investigated the coding system that children use to represent facial expression. An adaptation aftereffect paradigm was used to test 24 adults and 18 children (9 years 2 months to 9 years 11 months old). Participants adapted to weak and strong antiexpressions. They then judged the expression of an average expression. Adaptation created aftereffects that made the test face look like the expression opposite that of the adaptor. Consistent with the predictions of norm-based but not exemplar-based coding, aftereffects were larger for strong than weak adaptors for both age groups. Results indicate that, like adults, childrens coding of facial expressions is norm-based.

The expressions of strangers: Our identity-independent representation of facial expression

Evidence suggests that underlying the human system processing facial expressions are two types of representation of expression: one dependent on identity and the other independent of identity. We recently presented findings indicating that identity-dependent representations are encoded using a prototype-referenced scheme, in a manner notably similar to that proposed for facial identity. Could it be that identity-independent representations are encoded this way too? We investigated this by adapting participant to anti-expressions and asking them to categorize the expression aftereffect in a prototype probe that was either the same (congruent) or different (incongruent) identity to that of the adapter. To distinguish between encoding schemes, we measured how aftereffect magnitude changed in response to variations in the strength of adapters. The increase in aftereffect magnitude with adapter strength characteristic of prototype-referenced encoding was observed in both congruent and, crucially, incongruent conditions. We conclude that identity-independent representations of expression are indeed encoded using a prototype-referenced scheme. The striking similarity between the encoding of facial identity and both representations of expression raises the possibility that prototype-referenced encoding might be a common scheme for encoding the many types of information in faces needed to enable our complex social interactions.

Impaired Recognition of Basic Emotions from Facial Expressions in Young People with Autism Spectrum Disorder: Assessing the Importance of Expression Intensity

It has been proposed that impairments in emotion recognition in ASD are greater for more subtle expressions of emotion. We measured recognition of 6 basic facial expressions at 8 intensity levels in young people (6–16 years) with ASD (N = 63) and controls (N = 64) via an Internet platform. Participants with ASD were less accurate than controls at labelling expressions across intensity levels, although differences at very low levels were not detected due to floor effects. Recognition accuracy did not correlate with parent-reported social functioning in either group. These findings provide further evidence for an impairment in recognition of basic emotion in ASD and do not support the idea that this impairment is limited solely to low intensity expressions.

On the edge: haptic discrimination of edge sharpness.

The increasing ubiquity of haptic displays (e.g., smart phones and tablets) necessitates a better understanding of the perceptual capabilities of the human haptic system. Haptic displays will soon be capable of locally deforming to create simple 3D shapes. This study investigated the sensitivity of our haptic system to a fundamental component of shapes: edges. A novel set of eight high quality shape stimuli with test edges that varied in sharpness were fabricated in a 3D printer. In a two alternative, forced choice task, blindfolded participants were presented with two of these shapes side by side (one the reference, the other selected randomly from the remaining set of seven) and after actively exploring the test edge of each shape with the tip of their index finger, reported which shape had the sharper edge. We used a model selection approach to fit optimal psychometric functions to performance data, and from these obtained just noticeable differences and Weber fractions. In Experiment 1, participants performed the task with four different references. With sharpness defined as the angle at which one surface meets the horizontal plane, the four JNDs closely followed Weber’s Law, giving a Weber fraction of 0.11. Comparisons to previously reported Weber fractions from other haptic manipulations (e.g. amplitude of vibration) suggests we are sufficiently sensitive to changes in edge sharpness for this to be of potential utility in the design of future haptic displays. In Experiment 2, two groups of participants performed the task with a single reference but different exploration strategies; one was limited to a single touch, the other unconstrained and free to explore as they wished. As predicted, the JND in the free exploration condition was lower than that in the single touch condition, indicating exploration strategy affects sensitivity to edge sharpness.

Evaluating clinical stop-smoking services globally: towards a minimum data set

Abstract Background and aims Behavioural and pharmacological support for smoking cessation improves the chances of success and represents a highly cost‐effective way of preventing chronic disease and premature death. There is a large number of clinical stop‐smoking services throughout the world. These could be connected into a global network to provide data to assess what treatment components are most effective, for what populations and in what settings. To enable this, a minimum data set (MDS) is required to standardize the data captured from smoking cessation services globally. Methods We describe some of the key steps involved in developing a global MDS for smoking cessation services and methodologies to be considered for their implementation, including approaches for reaching consensus on data items to include in a MDS and for its robust validation. We use informal approximations of these methods to produce an example global MDS for smoking cessation. Our aim with this is to stimulate further discussion around the development of a global MDS for smoking cessation services. Results Our example MDS comprises three sections. The first is a set of data items characterizing treatments offered by a service. The second is a small core set of data items describing clients’ characteristics, engagement with the service and outcomes. The third is an extended set of client data items to be captured in addition to the core data items wherever resources permit. Conclusions There would be benefit in establishing a minimum data set (MDS) to standardize data captured for smoking cessation services globally. Once implemented, a formal MDS could provide a basis for meaningful evaluations of different smoking cessation treatments in different populations in a variety of settings across many countries.

State anxiety and emotional face recognition in healthy volunteers

High trait anxiety has been associated with detriments in emotional face processing. By contrast, relatively little is known about the effects of state anxiety on emotional face processing. We investigated the effects of state anxiety on recognition of emotional expressions (anger, sadness, surprise, disgust, fear and happiness) experimentally, using the 7.5% carbon dioxide (CO2) model to induce state anxiety, and in a large observational study. The experimental studies indicated reduced global (rather than emotion-specific) emotion recognition accuracy and increased interpretation bias (a tendency to perceive anger over happiness) when state anxiety was heightened. The observational study confirmed that higher state anxiety is associated with poorer emotion recognition, and indicated that negative effects of trait anxiety are negated when controlling for state anxiety, suggesting a mediating effect of state anxiety. These findings may have implications for anxiety disorders, which are characterized by increased frequency, intensity or duration of state anxious episodes.

Aftereffects support opponent coding of expression

We used aftereffects to investigate the coding mechanisms underlying perception of facial expression. Recent evidence that some dimensions are common to the coding of both expression and identity suggests that the same type of coding system could be used for both attributes. Identity is adaptively opponent coded by pairs of neural populations tuned to opposite extremes of relevant dimensions. Therefore, the authors hypothesized that expression would also be opponent coded. An important line of support for opponent coding is that aftereffects increase with adaptor extremity (distance from an average test face) over the full natural range of possible faces. Previous studies have reported that expression aftereffects increase with adaptor extremity. Critically, however, they did not establish the extent of the natural range and so have not ruled out a decrease within that range that could indicate narrowband, multichannel coding. Here the authors show that expression aftereffects, like identity aftereffects, increase linearly over the full natural range of possible faces and remain high even for impossibly distorted adaptors. These results suggest that facial expression, like face identity, is opponent coded.

Deciding on race: A diffusion model analysis of race-categorisation

It has long been known that a persons race can affect their decisions about people of another race; an observation that clearly taps into some deep societal issues. However, in order to behave differently in response to someone elses race, you must first categorise that person as other-race. The current study investigates the process of race-categorisation. Two groups of participants, Asian and Caucasian, rapidly classified facial images that varied from strongly Asian, through racially intermediate, to strongly Caucasian. In agreement with previous findings, there was a difference in category boundary between the two groups. Asian participants more frequently judged intermediate images as Caucasian and vice versa. We fitted a decision model, the Ratcliff diffusion model, to our two choice reaction time data. This model provides an account of the processes thought to underlie binary choice decisions. Within its architecture it has two components that could reasonably lead to a difference in race category boundary, these being evidence accumulation rate and a priori bias. The latter is the expectation or prior belief that a participant brings to the task, whilst the former indexes sensitivity to race-dependent perceptual cues. Whilst we find no good evidence for a difference in a priori bias between our two groups, we do find evidence for a difference in evidence accumulation rate. Our Asian participants were more sensitive to Caucasian cues within the images than were our Caucasian participants (and vice versa). These results support the idea that differences in perceptual sensitivity to race-defining visual characteristics drive differences in race categorisation. We propose that our findings fit with a wider view in which perceptual adaptation plays a central role in the visual processing of own and other race.

Visual search for expressions and anti-expressions

We used visual search to explore whether the preattentive mechanisms that enable rapid detection of facial expressions are driven by visual information from the displacement of features in expressions, or other factors such as affect. We measured search slopes for luminance and contrast equated images of facial expressions and anti-expressions of six emotions (anger, fear, disgust, surprise, happiness, and sadness). Anti-expressions have an equivalent magnitude of facial feature displacements to their corresponding expressions, but different affective content. There was a strong correlation between these search slopes and the magnitude of feature displacements in expressions and anti-expressions, indicating feature displacement had an effect on search performance. There were significant differences between search slopes for expressions and anti-expressions of happiness, sadness, anger, and surprise, which could not be explained in terms of feature differences, suggesting preattentive mechanisms were sensitive to other factors. A categorization task confirmed that the affective content of expressions and anti-expressions of each of these emotions were different, suggesting signals of affect might well have been influencing attention and search performance. Our results support a picture in which preattentive mechanisms may be driven by factors at a number of levels, including affect and the magnitude of feature displacement. We note that indirect effects of feature displacement, such as changes in local contrast, may well affect preattentive processing. These are most likely to be nonlinearly related to feature displacement and are, we argue, an important consideration for any study using images of expression to explore how affect guides attention. We also note that indirect effects of feature displacement (for example, changes in local contrast) may well affect preattentive processing. We argue that such effects are an important consideration for any study using images of expression to explore how affect guides attention.

The effects of gamelike features and test location on cognitive test performance and participant enjoyment

Computerised cognitive assessments are a vital tool in the behavioural sciences, but participants often view them as effortful and unengaging. One potential solution is to add gamelike elements to these tasks in order to make them more intrinsically enjoyable, and some researchers have posited that a more engaging task might produce higher quality data. This assumption, however, remains largely untested. We investigated the effects of gamelike features and test location on the data and enjoyment ratings from a simple cognitive task. We tested three gamified variants of the Go-No-Go task, delivered both in the laboratory and online. In the first version of the task participants were rewarded with points for performing optimally. The second version of the task was framed as a cowboy shootout. The third version was a standard Go-No-Go task, used as a control condition. We compared reaction time, accuracy and subjective measures of enjoyment and engagement between task variants and study location. We found points to be a highly suitable game mechanic for gamified cognitive testing because they did not disrupt the validity of the data collected but increased participant enjoyment. However, we found no evidence that gamelike features could increase engagement to the point where participant performance improved. We also found that while participants enjoyed the cowboy themed task, the difficulty of categorising the gamelike stimuli adversely affected participant performance, increasing No-Go error rates by 28% compared to the non-game control. Responses collected online vs. in the laboratory had slightly longer reaction times but were otherwise very similar, supporting other findings that online crowdsourcing is an acceptable method of data collection for this type of research.