Daniel Schreij

OpenSesame: An open-source, graphical experiment builder for the social sciences

In the present article, we introduce OpenSesame, a graphical experiment builder for the social sciences. OpenSesame is free, open-source, and cross-platform. It features a comprehensive and intuitive graphical user interface and supports Python scripting for complex tasks. Additional functionality, such as support for eyetrackers, input devices, and video playback, is available through plug-ins. OpenSesame can be used in combination with existing software for creating experiments.

What is top-down about contingent capture?

In the present study, we explored the mechanisms involved in the contingent capture phenomenon, using a variant of the classic precuing paradigm of Folk, Remington, and Johnston (1992). Rather than keeping the target fixed over a whole block of trials (as has traditionally been done with contingent capture experiments), we encouraged participants to adopt a top-down set before each trial. If top-down attentional set determines which property captures attention, as is claimed by the contingent capture hypothesis, one would expect that only properties that match the top-down set would capture attention. We showed that even though participants knew what the target would be on the upcoming trial, both relevant and irrelevant properties captured attention (Experiment 1). An intertrial analysis (Experiments 1 and 2) showed that previous contingent capture findings may, to a large extent, be explained by intertrial priming. In addition, when participants were further forced into adopting the required top-down set (Experiments 3 and 4), irrelevant cues were suppressed, suggesting that top-down control might operate through disengagement of attention from the location of a property that does not match top-down goals. The present findings suggest that top-down control and intertrial priming make their own distinct contributions to the contingent capture phenomenon.

Abrupt onsets capture attention independent of top-down control settings

Previous research using a spatial cuing paradigm in which a distractor cue preceded the target has shown that new objects presented with abrupt onsets only capture attention when observers are set to look for them (e.g., Folk, Remington, & Johnston, 1992). In the present study, we used the same spatial cuing paradigm as Folk et al. (1992) to demonstrate that even when observers have an attentional set for a color singleton or a specific color feature, an irrelevant new object presented with an abrupt onset interfered with search. We also show that the identity of the abrupt-onset distractor affects responses to the target, indicating that at some point spatial attention was allocated to the abrupt onset. We conclude that abrupt onsets or new objects override a top-down set for color. Abrupt onsets or new objects appear to capture attention independently of top-down control settings.

Abrupt onsets capture attention independent of top-down control settings II: Additivity is no evidence for filtering

Is attentional capture contingent on top-down control settings or involuntarily driven by salient stimuli? Supporting the stimulus-driven attentional capture view, Schreij, Owens, and Theeuwes (2008) found that an onset distractor caused a response delay, in spite of participants’ having adopted an attentional set for a color feature. However, Folk, Remington, and Wu (2009) claimed that this delay reflects separate, nonspatial filtering costs instead, because the onset effects were additive with color-based capture effects, and capture should have caused underadditivity. The present Experiment 1 shows that contingent capture caused by additional color cues is also additive, just like the onset effect. This makes additivity a dubious diagnostic with regard to spatial capture. Experiment 2 demonstrates that it is possible to obtain underadditivity when attention-demanding distractors have sufficient capturing power. Experiment 3 shows that the abrupt onset interference turns into a benefit when the locations of the onset and the target coincide. Together, these results argue in favor of stimulus-driven attentional capture by abrupt onsets.

Irrelevant onsets cause inhibition of return regardless of attentional set

It is disputed whether onsets capture spatial attention either in a purely stimulus-driven fashion or only when they are contingent on one’s attentional set. According to the latter assumption, interference from irrelevant onsets may result from nonspatial filtering costs. In the present study, we used inhibition of return (IOR) as a marker for spatial attention. IOR occurs mainly for locations that attention has visited before. Participants searched for a red object among white objects. An attentional set for redness was demonstrated by a spatial validity effect of red cues on response times. However, a stronger validity effect was found for irrelevant white onsets, which slowed responses when the onset contained a distractor, but speeded them when the onset contained a target. Most importantly, this onset benefit for targets turned into a deficit at longer SOAs, indicating IOR. We conclude that onset distractors capture spatial attention regardless of the observer’s attentional set.

The interaction between stimulus-driven and goal-driven orienting as revealed by eye movements

It is generally agreed that attention can be captured in a stimulus-driven or in a goal-driven fashion. In studies that investigated both types of capture, the effects on mean manual response time (reaction time [RT]) are generally additive, suggesting two independent underlying processes. However, potential interactions between the two types of capture may fail to be expressed in manual RT, as it likely reflects multiple processing steps. Here we measured saccadic eye movements along with manual responses. Participants searched a target display for a red letter. To assess contingent capture, this display was preceded by an irrelevant red cue. To assess stimulus-driven capture, the target display could be accompanied by the simultaneous onset of an irrelevant new object. At the level of eye movements, the results showed strong interactions between cue validity and onset presence on the spatiotemporal trajectories of the saccades. However, at the level of manual responses, these effects cancelled out, leading to additive effects on mean RT. We conclude that both types of capture influence a shared spatial orienting mechanism and we provide a descriptive computational model of their dynamics.

Object representations maintain attentional control settings across space and time

Previous research has revealed that we create and maintain mental representations for perceived objects on the basis of their spatiotemporal continuity. An important question is what type of information can be maintained within these so-called object files. We provide evidence that object files retain specific attentional control settings for items presented inside the object, even when it disappears from vision. The objects were entire visual search displays consisting of multiple items moving into and out of view. It was demonstrated that search was speeded when the search target position was repeated from trial to trial, but especially so when spatiotemporal continuity suggested that the entire display was the same object. We conclude that complete spatial attentional biases can be stored in an object file.

Looking at paintings in the Vincent Van Gogh Museum: Eye movement patterns of children and adults

In the present study, we examined the eye movement behaviour of children and adults looking at five Van Gogh paintings in the Van Gogh Museum, Amsterdam. The goal of the study was to determine the role of top-down and bottom-up attentional processes in the first stages of participants’ aesthetic experience. Bottom-up processes were quantified by determining a salience map for each painting. Top-down processing was manipulated by first allowing participants to view the paintings freely, then providing background information about each painting, and then allowing them to view the paintings a second time. The salience analysis showed differences between the eye movement behaviour of children and adults, and differences between the two phases. In the children, the first five fixations during the free viewing phase were strongly related to visually salient features of the paintings—indicating a strong role for bottom-up factors. In the second phase, after children had received background information, top-down factors played a more prominent role. By contrast, adults’ observed patterns were similar in both phases, indicating that bottom-up processes did not play a major role when they viewed the paintings. In the second phase, children and adults both spent more time looking at regions that were mentioned in the background information. This effect was greater for adults than for children, confirming the notion that adults, when viewing paintings, rely much more on top-down processing than children.

Visual memory performance for color depends on spatiotemporal context

Performance on visual short-term memory for features has been known to depend on stimulus complexity, spatial layout, and feature context. However, with few exceptions, memory capacity has been measured for abruptly appearing, single-instance displays. In everyday life, objects often have a spatiotemporal history as they or the observer move around. In three experiments, we investigated the effect of spatiotemporal history on explicit memory for color. Observers saw a memory display emerge from behind a wall, after which it disappeared again. The test display then emerged from either the same side as the memory display or the opposite side. In the first two experiments, memory improved for intermediate set sizes when the test display emerged in the same way as the memory display. A third experiment then showed that the benefit was tied to the original motion trajectory and not to the display object per se. The results indicate that memory for color is embedded in a richer episodic context that includes the spatiotemporal history of the display.

The role of space and time in object-based visual search

Recently we have provided evidence that observers more readily select a target from a visual search display if the motion trajectory of the display object suggests that the observer has dealt with it before. Here we test the prediction that this object-based memory effect on search breaks down if the spatiotemporal trajectory is disrupted. Observers searched a display for a target shape among multiple distractors. The entire search display then passed behind an occluder and reemerged in either the same or a different configuration. Experiment 1 shows that the same-object benefit for selection disappears whenever a spatial disruption is involved, but that it may survive a brief temporal disruption. Experiment 2 shows that with sufficiently long gaps, a temporal disruption also destroys the same-object benefit for selective attention. Experiment 3 demonstrates that the same-object effect is even stronger when there only is a very small probability that the target can be found at the same location as before. This also made the task sensitive to brief temporal disruptions. We conclude that a coherent spatiotemporal history of a display object supports the selection of its relevant subregions.