The relationship between allocentric and egocentric frames of reference and categorical and coordinate spatial information processing

We report two experiments on the relationship between allocentric/egocentric frames of reference and categorical/coordinate spatial relations. Jager and Postma (2003) suggest two theoretical possibilities about their relationship: categorical judgements are better when combined with an allocentric reference frame and coordinate judgements with an egocentric reference frame (interaction hypothesis); allocentric/egocentric and categorical/coordinate form independent dimensions (independence hypothesis). Participants saw stimuli comprising two vertical bars (targets), one above and the other below a horizontal bar. They had to judge whether the targets appeared on the same side (categorical) or at the same distance (coordinate) with respect either to their body-midline (egocentric) or to the centre of the horizontal bar (allocentric). The results from Experiment 1 showed a facilitation in the allocentric and categorical conditions. In line with the independence hypothesis, no interaction effect emerged. To see whether the results were affected by the visual salience of the stimuli, in Experiment 2 the luminance of the horizontal bar was reduced. As a consequence, a significant interaction effect emerged indicating that categorical judgements were more accurate than coordinate ones, and especially so in the allocentric condition. Furthermore, egocentric judgements were as accurate as allocentric ones with a specific improvement when combined with coordinate spatial relations. The data from Experiment 2 showed that the visual salience of stimuli affected the relationship between allocentric/egocentric and categorical/coordinate dimensions. This suggests that the emergence of a selective interaction between the two dimensions may be modulated by the characteristics of the task.     

Perceived bending motions from a quadrangle changing form

In an earlier study by Jansson and Johansson it was found that rotation of a rigid object is perceptually preferred over bending motion, and that bending motion in turn is preferred over two-dimensional stretching. The aim of the present experiment was to study if the same preference order is retained also when the proximal stimuli are changing in a physically more complex way. The stimuli were quadrangular outline figures with two stationary and two moving corners; the figures differed in degree of phase lag between the motions of the two corners. The result was that the preference order found earlier was retained. It was also found that the relative frequency of two subcategories of bending motion, bending proper and folding, varied with phase lag. The relation of the result to a principle of minimum object change was discussed.     

Multiple microswitches for persons with multiple disabilities: a basic procedure to examine the persons' choice behavior

This study examined a basic choice-analysis procedure to clarify choice between two responses and related stimuli by five persons with multiple disabilities ages 17.1 to 50.2 yr. The procedure was based on reversing the links between responses and stimuli to assess whether the stimuli accounted for differences in response levels. When this was not the case, the procedure added extra stimuli for the less preferred response to judge whether such an increase would compensate for the apparent disadvantage of that response, e.g., its higher physical cost. Analysis showed that the choice of three of the five participants seemed motivated by the stimuli following the responses. The choice of the other two persons seemed related to a preference for one of the responses which was partially or largely modified when extra stimuli were added.     

Dimensions of the perception of art: verbal scales and similarity judgements

Abstract.— An INDSCAL analysis was performed on subjects' similarity judgements of all pairs of 12 landscape paintings. Three principal INDSCAL dimensions were identified by analysing responses to 24 unidimensional rating scales derived from previous experiments. The present findings, together with those of previously published studies, suggest that three of the principal dimensions of perception of art appear to be (1) Hedonic-Representational, (2) Clarity, (3) A Dynamic factor involving activity, balance and symmetry. It is suggested that although Complexity may be an important factor influencing responses to simple stimuli, its rôle in the perception of paintings is small, and has frequently been over-emphasised.     

The relationship between allocentric and egocentric frames of reference and categorical and coordinate spatial information processing

We report two experiments on the relationship between allocentric/egocentric frames of reference and categorical/coordinate spatial relations. Jager and Postma (2003) suggest two theoretical possibilities about their relationship: categorical judgements are better when combined with an allocentric reference frame and coordinate judgements with an egocentric reference frame (interaction hypothesis); allocentric/egocentric and categorical/coordinate form independent dimensions (independence hypothesis). Participants saw stimuli comprising two vertical bars (targets), one above and the other below a horizontal bar. They had to judge whether the targets appeared on the same side (categorical) or at the same distance (coordinate) with respect either to their body-midline (egocentric) or to the centre of the horizontal bar (allocentric). The results from Experiment 1 showed a facilitation in the allocentric and categorical conditions. In line with the independence hypothesis, no interaction effect emerged. To see whether the results were affected by the visual salience of the stimuli, in Experiment 2 the luminance of the horizontal bar was reduced. As a consequence, a significant interaction effect emerged indicating that categorical judgements were more accurate than coordinate ones, and especially so in the allocentric condition. Furthermore, egocentric judgements were as accurate as allocentric ones with a specific improvement when combined with coordinate spatial relations. The data from Experiment 2 showed that the visual salience of stimuli affected the relationship between allocentric/egocentric and categorical/coordinate dimensions. This suggests that the emergence of a selective interaction between the two dimensions may be modulated by the characteristics of the task.     

Antecedent manipulations in a tangible condition: effects of stimulus preference on aggression.

After a functional analysis indicated that aggression of an 8‐year‐old boy with autism was maintained by access to preferred items, antecedent manipulations involving the relative preference of restricted and noncontingently available stimuli were conducted. Restricting highly preferred items evoked the highest rates of aggression regardless of the preference level of the noncontingently available alternative items. Restricting less preferred stimuli was associated with moderate rates of aggression even when the alternative items were more preferred.     

Hypothesis analysis of sameness-difference learning-set by capuchin monkeys

Sameness-difference discriminations were presented to capuchin monkeys and hypothesis analysis was applied to the data. Learners and nonlearners evidenced differences in overall performance and in relative strengths of hypotheses. Learners initially displayed markedly more random than position responding whereas nonlearners evidenced more position than random responding and remained particularly prone to position habits. Stimulus preference and aversion, suppressed by learners by the end of training, reemerged at the onset of two-object discriminations containing previously preferred and aversive stimuli. Hypothesis analysis indicated that when preferred stimuli were positive the correct hypothesis was more evidenced, and stimulus preference or aversion as well as random hypotheses were less evidenced, than when aversive stimuli were positive.     

Freedom and knowledge: an experimental analysis of preference in pigeons

Relative responding in initial links of concurrent-chain schedules showed that pigeons preferred free to forced choices and informative to uninformative stimuli. Variable-interval initial links on two lower keys (white) of a six-key chamber produced terminal links on either two upper-left keys (blue and/or amber) or two upper-right keys (green and/or red). Terminal.links in which pecks on either of two lit keys produced fixed-interval reinforcement (free choice) were preferred to links with only one lit fixed-interval key available (forced choice). Terminal links with different key colors correlated with concurrent fixed-interval reinforcement and extinction (informative stimuli) were preferred to links with these schedules operating on same-color keys (uninformative stimuli). Scheduling extinction for one of the two free-choice keys assessed preference for two lit keys over one lit key, but confounded number with whether stimuli were informative. Fixed-interval reinforcement for both keys in each terminal link, but with different-color keys in one link and same-color keys in the other, showed that preference for informative stimuli did not depend on stimulus variety. Preferences were independent of relative responses per reinforcement and other properties of terminal-link performance.     

Complexity and facial resemblance as determinants of response to facelike stimuli by 5-and 10-week-old infants

The purpose of this experiment was to determine whether infants at 5 and at 10 weeks of age respond to facelike drawings on the basis of stimulus complexity or on the basis of degree of resemblance to the human face. Twenty-four Ss at each age were shown four patterns in which these two dimensions were varied orthogonally. Fixation time was recorded using the successive, single stimulus procedure. Results provided no evidence of response to the facial resemblance dimension at either age level. However, there was a significant complexity component in the responses of both groups. The 5-week-old infants preferred an intermediate level of stimulus complexity. Those at 10 weeks showed a linear preference for increasing levels of the complexity dimension.     

INCREASING INDICES OF HAPPINESS AMONG PEOPLE WITH PROFOUND MULTIPLE DISABILITIES: A PROGRAM REPLICATION AND COMPONENT ANALYSIS

We replicated a program to increase indices of happiness among people with profound multiple disabilities and conducted a component analysis of the program. The program involved presentation and contingent withdrawal of stimuli that had been identified as preferred based on preference assessments and staff opinion. The program was implemented with 3 adult students and was accompanied by increased happiness indices for each student. Subsequent implementation of the two types of stimuli indicated that preferred stimuli based on preference assessments were more consistently accompanied by increased happiness indices than were preferred stimuli based on staff opinion. Social validity measures supported the definition of happiness, in that raters' subjective opinions of the students' happiness coincided with the observed happiness indices. Results are discussed regarding the importance and practical implications of using preference assessments for determining stimuli for increasing happiness indices. Future research areas are suggested, focusing on increasing happiness and other quality-of-life indicators during the daily routines of people with profound disabilities.     

EVALUATION OF A BRIEF STIMULUS PREFERENCE ASSESSMENT

We evaluated the utility of a brief (5-min) stimulus preference assessment for individuals with developmental disabilities. Participants had noncontingent (free) access to an array of stimuli and could interact with any of the stimuli at any time. Stimuli were never withdrawn or withheld from the participants during a 5-min session. In Experiment 1, the brief preference assessment was conducted for 10 participants to identify differentially preferred stimuli, and reinforcer assessments were conducted to test the reinforcing efficacy of those stimuli identified as highly preferred. In Experiment 2, a comparison was conducted between the brief preference assessment and a commonly used paired-stimulus preference assessment. Collectively, results demonstrated that the brief preference assessment identified stimuli that functioned as reinforcers for a simple operant response, identified preferred stimuli that were differentially effective as reinforcers compared to nonpreferred stimuli, was associated with fewer problem behaviors, and required less time to complete than a commonly used paired-stimulus preference assessment.     

Teacher report and direct assessment of preferences for identifying reinforcers for young children

Teachers were asked to identify and rank 10 preferred stimuli for 9 toddlers, and a hierarchy of preference for these items was determined via a direct preference assessment. The reinforcing efficacy of the most highly preferred items identified by each method was evaluated concurrently in a reinforcer assessment. The reinforcer assessment showed that all stimuli identified as highly preferred via the direct preference assessment and teacher rankings functioned as reinforcers. The highest ranked stimuli in the direct assessment were more reinforcing than the teachers' top-ranked stimuli for 5 of 9 participants, whereas the teachers' top-ranked stimulus was more reinforcing than the highest ranked stimulus of the direct assessment for only 1 child. A strong positive correlation between rankings generated through the two assessments was identified for only 1 of the 9 participants. Despite poor correspondence between rankings generated through the teacher interview and direct preference assessment, results of the reinforcer assessment suggest that both methods are effective in identifying reinforcers for toddlers.     

TWO MEASURES OF PREFERENCE DURING FORCED-CHOICE ASSESSMENTS

A forced-choice preference assessment was conducted in which two dependent measures were used to select preferred stimuli: (a) approach responding and (b) latency to the first aberrant response. Stimuli identified as preferred based on both dependent measures were then evaluated during treatment. The results suggested that latency may be a useful measure in the selection of preferred stimuli during forced-choice assessments.     

Enabling two adolescents with multiple disabilities to choose among environmental stimuli through different procedural and technological approaches

Two single-case studies were carried out using different procedural and technological approaches to enable two adolescents with multiple disabilities to choose among environmental stimuli. Study I focused on replicating a recently developed procedure, which relied on samples of the auditory stimuli available as cues for choice responses. Study II assessed a new procedural and technical setup relying on the use of pictorial representations of the stimuli available as cues for choice responses. The auditory samples and the pictorial representations were presented through computer systems. The participants' choice responses relied on microswitches connected to the computer systems. The data of Study I fully supported previous findings with the same procedural approach. The participant learned to choose preferred stimuli and bypass nonpreferred ones. The data of Study II showed that the participant learned to concentrate his choice. responses on a few stimuli, suggesting that these stimuli were actually preferred and that responding was purposeful. Implications of the results were discussed.     

The psychological distance to reward

Pigeons' responses in the presence of two concurrently available (initial-link) stimuli produced entry into one of two different and mutually exclusive terminal link stimuli according to identical but independent variable-interval schedules. In one experiment, a two-component chained fixed-interval schedule produced food in one terminal link while a simple fixed-interval schedule produced food in the other terminal link. When the interreinforcement intervals were equal in the two terminal links (i.e., the simple fixed-interval was twice the size of each of the components in the chained schedule) pigeons preferred the simple fixed-interval as measured by their relative rates of responding in the concurrently available initial links. This preference increased as the duration of the terminal links increased. The preference could be reversed by making the simple fixed-interval schedule sufficiently longer than the chained schedule. In the second experiment, the terminal links consisted of two- vs three-component chained fixed-intervals, again with equal interreinforcement intervals. Pigeons preferred the two-component chain to the three-component chain, although these results were less consistent and less dramatic than those in the first experiment. Again, preference increased as the duration of the terminal links increased. The results show that an organism's choice for a schedule will be substantially lowered by the chaining operation even when the interreinforcement interval remains constant.     

Further examination of video‐based preference assessments without contingent access

The first purpose of this study was to attempt to replicate previous findings that video‐based preference assessments without access to selected stimuli may accurately predict relative reinforcing efficacy of stimuli. To do this, we conducted a concurrent operant reinforcer assessment in which we evaluated the relative reinforcing value of highly preferred and less preferred items identified in a video‐based preference assessment. The second purpose of this study was to begin to evaluate the potential behavioral mechanisms responsible for the validity of this assessment. To conduct this analysis, we evaluated the relative reinforcing value of those same stimuli depicted in video format and then compared results to results obtained during the reinforcer assessment for tangible stimuli. For all five participants, stimuli identified as highly preferred functioned as reinforcers, and four of five participants, responding during the reinforcer assessment was similar in the presence of tangible stimuli and videos depicting those stimuli.     

Response summation to a compound stimulus in a context of choice

Key pecks by two groups of pigeons were reinforced on concurrent schedules. For group Ē, pecks were reinforced during either a visual or an auditory stimulus; for group E, an additional, extinction component was available, during which both visual and auditory stimuli were absent. After training, both groups were given a compound test to measure preference among four stimuli, the three used in training plus a compound of the visual and auditory stimulus. Group E showed preference for the compound, emitting more pecks and spending more time in this stimulus than in other stimuli. Group Ē showed no preference between the compound and visual stimulus, nor between the auditory stimulus and the absence of both stimuli, but preferred the former pair over the latter pair of stimuli.     

AN ANALOGUE EVALUATION OF ENVIRONMENTAL ENRICHMENT: THE ROLE OF STIMULUS PREFERENCE

To evaluate the effects of environmental enrichment on stereotypic self-injurious behavior (SIB), we conducted an assessment of preference for manipulating alternative stimuli rather than engaging in SIB. First, for each of 3 participants, a functional analysis of SIB was conducted in Phase 1. Participants were selected for Phase 2 if the functional analysis showed that SIB persisted in the absence of social consequences. In Phase 2, a preference assessment was conducted in which participants were observed manipulating preferred stimuli in a free-operant format. A measure was taken of time spent manipulating each stimulus and time spent engaging in SIB. In Phase 3, environmental enrichment was evaluated using stimuli that were preferred over the target response, and alternative treatments were evaluated in the event of environmental enrichment failure. Results suggested that the free-operant preference assessment (a) predicted the efficacy or inefficacy of an environmental enrichment procedure and (b) suggested possible treatment alternatives when environmental enrichment was ineffective. Collectively, the results may provide a basis for interpreting the idiosyncratic effects of environmental enrichment and a rationale for treatment selection when behavioral function is unknown.     

UCS expectancy biases in spider phobics: underestimation of aversive consequences following fear-irrelevant stimuli

This paper reports the results of two studies investigating judgements made by spider phobics about the potential threatening consequences (unconditioned stimulus, UCS, expectancies) associated with their phobic stimulus, fear-relevant (FR) stimuli, and fear-irrelevant (FI) stimuli. Using a 'thought experiment' UCS expectancy paradigm, the studies reported found that (1) spider phobics reported significantly higher UCS expectancies to spider stimuli than nonphobics, (2) spider phobics consistently underestimated the probability of aversive consequences following FI stimuli and (3) this underestimation of UCS expectancies to FI stimuli in phobics was not the result of a contrast effect resulting from sequential FR and FI judgements. This differential effect may have important implications for the kind of mechanism which mediates judgements about phobic consequences. These findings suggest that the dimensions on which phobic stimuli are categorised may be 'stretched' in the case of phobics and that this gives rise to the comparative underestimation of threat associated with FI stimuli but also makes phobics more vulnerable to acquiring other phobias.     

Social comparison on two dimensions

In this experiment social comparison on two task dimensions has been studied. The subjects received bogus feedback on their performance on two tests, one allegedly measuring creativity, the other alertness. By means of this feedback four relative position conditions were induced: scoring high on both tests, scoring low on both tests, scoring high on creativity and low on alertness, and vice versa. Anticipating either a co-operative or a competitive game, the subjects indicated their preference for one or the other task dimension and also expressed their preference for a comparison person. It was found that, as predicted, the subjects preferred and valued comparison dimensions on which they occupied a favourable position. With respect to preference for a comparison person, compensatory choices were obtained: on the dimension on which the subject performed well, they preferred an inferior other. On the dimension on which they performed poorly, they preferred a superior other. This pattern of choices was found in co-operation as well as in competition. Finally, upward preference was stronger in co-operative than in competitive conditions, particularly on the dimension on which the subject's own score was low. These and other results were discussed in relation to theoretical social comparison notions.