Equivalence relations and the contextual control of multiple derived stimulus functions

Contextual control is a key aspect in equivalence research to support the claim that stimuli may have multiple functions or symbols may have multiple meanings. The present study investigated the contextual control of multiple derived stimulus functions in two experiments. In Experiment 1, equivalence classes were formed and one stimulus set from each class was used to establish two different functions: one via positive reinforcement (key-pressing) and another via negative reinforcement (button clicking), both under contextual control of two different background colors. Later, other stimuli from the equivalence class were presented on those background colors and contextual control of multiple derived stimulus functions was assessed. Experiment 2 added a third background in which no programmed response was reinforced, that is, responses were extinguished. Transfer-of-function tests revealed contextual control of three different functions, including derived extinction. Implications for equivalence relations as a behavior-analytical model of symbolic functioning are discussed.     

Equivalence class formation when responding is separated from sample and comparison stimuli: Working memory,priming, and sorting

The experiment determined whether equivalence class formation required overlap of comparison stimuli and responding. Each trial contained a sample first, a single, nonoverlapping comparison second, and a nonoverlapping response-window (RW) third, during which the participant made one of two responses (2R). All 11 participants formed two 3-member ABC equivalence classes using these “trace-stimulus-pairing two-response with response window” (TSP-2R-RW) trials. After adding a fourth stimulus (D) by CD training, ABCD tests showed immediate expansion to 4-member ABCD classes. When 4-member probes (AD, DA, BD, DB, CD, DC) were administered without 3-member probes, many participants showed decrements in class-indicative responding that then resurged to mastery with test repetition. Thus, 3-member probes enhanced class expansion. Class formation occurred for all participants when responding was temporally dissociated from the comparisons. In a matched, contemporaneously published experiment, where responding occurred during comparisons, only 54% of participants formed the classes. Thus, the comparison-response-separation nearly doubled class formation. Additionally, a special post-class-formation sorting test documented the emergence of two explicit equivalence classes. Finally, we noted a 1:1 correspondence for TSP-2R-RW and priming trials. Since priming measures neural substrates of equivalence classes, TSP-2R-RW trials should do the same.     

Expansion of arbitrary stimulus classes and function-transfer measured by sorting performances

Sorting (SRT) and matching-to-sample (MTS) tests have measured the formation of arbitrary stimulus classes. This experiment used SRT and MTS tests to document the expansion of class size. Thirty-two participants learned 12 conditional discriminations with a linear series training structure (A➔B➔C➔D➔E). SRT tests documented the formation of 5-member classes by 17 of the participants. Thereafter, 6-member class expansion was implemented by FC training. Nine of these 17 participants showed class expansion when tracked with a sequence of an SRT, MTS, and a final SRT test, and the other 8 showed expansion when tracked with a sequence of MTS and SRT tests. Thus, SRT tests documented class expansion, and the sequence of tests did not influence class expansion. The 15 participants who did not form the 5-member classes learned the baselines for new 3-member classes (A➔B➔C) and formed them as documented by an SRT test. Then, 4-member class expansion was implemented by FB training. Expansion was assessed using the above-mentioned testing sequences. All 15 showed class expansion with 100% correspondence between the SRT and MTS performances. Sorting documented the expansion of arbitrary stimulus classes, while the MTS tests showed that the stimuli also functioned as members of equivalence classes.     

汉语双字词句知觉广度的眼动研究

阅读知觉广度通常指阅读者在阅读文本过程中每次注视能获取有用视觉信息的范围。既往的汉语知觉广度的研究一般把单字作为基本的知觉呈现单元,但在某些呈现条件下,此类呈现方式会导致阅读过程中的语义加工的完整性被破坏。本研究采用眼动追踪技术,使用移动窗口范式和中央凹掩蔽范式,使用双字词句作为阅读材料,双字词作为基本的知觉呈现单元,探讨在保证知觉呈现单元语义完整性的基础上大学生的汉语阅读知觉广度。实验一采用移动窗口范式,结果发现,知觉广度范围为注视词左侧1个双字词及右侧1-2个双字词的空间。实验二采用中央凹掩蔽范式,结果验证了实验一的研究结果。该结果表明,在汉语阅读过程中,以双字词为基本的视觉呈现单元,较既往研究中单字为基本呈现单元的情况,更好地保证了阅读中语义的完整性,从而获得了更大的知觉范围。该结果建立于视觉呈现单元的语义完整性的基础上,是对现有的汉语阅读知觉广度理论的完善和扩展。     

Is ‘object-centred neglect’ a homogeneous entity?

The nature of object-centred (allocentric) neglect and the possibility of dissociating it from egocentric (subject-centred) forms of neglect are controversial. Originally, allocentric neglect was described by  and  in patients who reproduced all the elements of a multi-object scene, but left unfinished the left side of one or more of them. More recently, however, Karnath, Mandler, and Clavagnier (2011) have claimed that the severity of allocentric neglect worsens when a complex ‘object’ shifts from an ipsilesional to a contralesional egocentric position. On the basis of these and of other clinical data, showing that allocentric and egocentric neglect are strongly associated, they have questioned the possibility of dissociating these two forms of neglect, suggesting that egocentric and allocentric neglect constitute different manifestations of the same disturbed system. Since these statements were inconsistent with the clinical findings which had prompted the construct of object-centred neglect, we checked in a group of right brain-damaged patients, who had copied the original multi-object scene, if the degree of neglect for the left side of figures varied as a function of their position on the horizontal axis. Furthermore, we reviewed all papers where copies of other multi-object scenes had been reported. Results of both studies failed to confirm the assumption of a relationship between spatial location of the stimulus and severity of object-centred neglect. This discrepancy between our data and those obtained by Karnath et al. (2011) could be due to the characteristics of stimuli and of procedures used to evaluate ‘object-centred’ neglect. If the stimulus is complex and the task requires its thorough exploration, the spatial location of the stimulus will influence the severity of ‘object-centred neglect’. If, on the contrary, the stimulus is simple and can be identified with few eye fixations, the spatial location of the stimulus should not influence the severity of ‘object-centred neglect’. In any case, our data confirm the possibility of dissociating allocentric from egocentric neglect.     

Flanker and Simon effects interact at the response selection stage

The present study aimed at investigating the processing stage underlying stimulus–stimulus (S–S) congruency effects by examining the relation of a particular type of congruency effect (i.e., the flanker effect) with a stimulus–response (S–R) spatial correspondence effect (i.e., the Simon effect). Experiment 1 used a unilateral flanker task in which the flanker also acted as a Simon-like accessory stimulus. Results showed a significant S–S Congruency × S–R Correspondence interaction: An advantage for flanker–response spatially corresponding trials was observed in target–flanker congruent conditions, whereas, in incongruent conditions, there was a noncorresponding trials' advantage. The analysis of the temporal trend of the correspondence effects ruled out a temporal-overlap account for the observed interaction. Moreover, results of Experiment 2, in which the flanker did not belong to the target set, demonstrated that this interaction cannot be attributed to perceptual grouping of the target–flanker pairs and referential coding of the target with respect to the flanker in the congruent and incongruent conditions, respectively. Taken together, these findings are consistent with a response selection account of congruency effects: Both the position and the task-related attribute of the flanker would activate the associated responses. In noncorresponding-congruent trials and corresponding-incongruent trials, this would cause a conflict at the response selection stage.     

The interplay between presentation material and decision mode for complex choice preferences

Recent research suggests that, when faced with a choice between several alternatives described with a large number of attributes, people make better choices if they do not consciously ponder over the alternatives but rather perform a distraction task assumed to elicit unconscious thought. Subsequent research attempting to replicate this finding, however, provided mitigated support for its existence. The research reported here contributes to this ongoing debate on two grounds. First, it highlights a methodological confound between qualitative and quantitative presentation material and proposes a novel procedure that can accommodate both. Second, it shows that, whereas conscious deliberation leads to better decisions when alternatives are characterised by quantitative information, the use of a qualitative format for presenting information cancels the advantage of conscious deliberation.     

Wheel chairs and arm chairs: A novel experimental design for the emotional Stroop effect

The emotional Stroop effect demonstrates that people are slower to name the ink colour of emotionally charged words than that of neutral words. Attributing this slowdown to emotionality or threat requires that the emotion and neutral words presented are equal on all extraneous variables. However, it is impossible in principle to match the two types of words on all conceivable variables. To address the problem, we presented the same set of words, polarised to be negative in one condition and neutral in another by using appropriate prime words that produced the desired valence through idiomatic two-word expressions. Across two studies, participants took longer to name the colour of the same words when they were rendered negative than when they were rendered neutral. This difference reflects a true emotional Stroop effect given the control provided for all potentially confounding variables tied to the target stimuli. The new procedure also enables researchers to calculate item-specific emotional Stroop effects for the first time.