Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Breaking Ball Too Good to be True

14.10.2010
Curveballs curve and fastballs go really fast, but new research suggests that no pitcher can make a curveball “break” or a fastball “rise.”

Led by Arthur Shapiro of American University and Zhong-Lin Lu of the University of Southern California, the researchers explain the illusion of the curveball’s break in a publicly available study in the journal PLoS ONE (study available by request or post-embargo at http://dx.plos.org/10.1371/journal.pone.0013296).

The study comes a year after the same group won the prize for best illusion at the Vision Sciences annual meeting with a demonstration of how an object falling in a straight line can seem to change direction (http://illusioncontest.neuralcorrelate.com/2009/the-break-of-the-curveball/).

That demonstration led to debates among baseball fans over the existence of the break in curveballs, breaking balls and sliders.

There is no debate in the researchers’ minds.

“The curveball does curve, but the curve has been measured and shown to be gradual,” Shapiro said. “It’s always going to follow a parabolic path. But from a hitter’s point of view, an approaching ball can appear to break, drop or do a whole range of unusual behaviors.”

A little terminology: to many batters and pitchers, a break is a deviation from the relatively straight path of a fastball. In that sense, all curveballs break.

The authors of the study use the term to describe an apparent sudden drop or other change in trajectory as the ball nears home plate. That, they say, is an illusion.

The PLoS ONE study explains the illusion and relates the perceived size of the break to the shifting of the batter’s eye between central and peripheral vision.

“If the batter takes his eye off the ball by 10 degrees, the size of the break is about one foot,” Lu said.

He explained that batters tend to switch from central to peripheral vision when the ball is about 20 feet away, or two-thirds of the way to home plate. The eye’s peripheral vision lacks the ability to separate the motions of the spinning ball, Lu said. In particular, it gets confused by the combination of the ball’s velocity and spin.

The result is a gap between the ball’s trajectory and the path as perceived by the batter. The gap is small when the batter switches to peripheral vision, but gets larger as the ball travels the last 20 feet to home plate.

As the ball arrives at the plate, the batter switches back to central vision and sees it in a different spot than expected. That perception of an abrupt change is the “break” in the curveball that frustrates batters.

“Depending on how much and when the batter’s eyes shift while tracking the ball, you can actually get a sizable break,” Lu said. “The difference between central and peripheral vision is key to understanding the break of the curveball.”

A similar illusion explains the “rising fastball,” Lu added.

The obvious remedy for a batter, repeated by parents and coaches everywhere, is to “keep your eye on the ball.”

That is easier said than done, according to the authors. As the ball nears home plate, its size in the batter’s field of view spills out of the eye’s central vision.

“Our central vision is very small,” Shapiro said. “It’s the size of the tip of your thumb at arm’s length. When an object falls outside of that region, strange perceptions can occur.”

Lu noted that the spin of the ball tends to draw the eye to the side, making it even harder for the batter to keep the ball in central vision.

“People’s eyes have a natural tendency to follow motion,” Lu explained.

His advice to hitters: “Don’t trust your eyes. Know the limitations of your visual system. This is something that can be trained, probably.”

Lu, Shapiro and their co-authors plan to build a physical device to test the curveball illusion. Their study was carried out with volunteers tracking the movement of a disk on a computer monitor.

To the authors’ knowledge, the PLoS ONE study represents the first attempt to explain the break in the curveball purely as a visual illusion. Others have tried to explain the break as a result of the hitter overestimating the speed of a pitch.

Responding to comments from baseball fans, Lu agreed that on television, pitches filmed from behind home plate appear to break. He called it a “geometric illusion” based on the fact that for the first part of a pitch, the viewer sees little or no vertical drop.

The ball is falling at the same rate throughout the pitch, Lu said, but because the pitcher tosses the ball at a slight upward angle, the first part of the pitch appears more or less flat.

As a result, the drop of the ball near home plate surprises the eye.

For Shapiro and Lu, who have studied visual perception for many years, the PLoS ONE results go beyond baseball.

“Humans constantly shift objects between central and peripheral vision and may encounter effects like the curveball’s break regularly,” the authors wrote. “Peripheral vision’s inability to separate different visual signals may have far-reaching implications in understanding human visual perception and functional vision in daily life.”

Lu, a professor of psychology and biomedical engineering at USC, holds the William M. Keck Chair in Cognitive Neuroscience. In addition to first author Shapiro, the co-authors were Chang-Bing Huang of USC, Emily Knight of the Mayo Clinic and Robert Ennis of the SUNY College of Optometry.

To read a LiveScience interview with Lu from last year, go to http://www.livescience.com/culture/091102-sl-lu.html

The research was partially supported by the National Eye Institute.

HOW THE EXPERIMENT WAS CONDUCTED:

The authors estimated the magnitude of the illusion by measuring the physical angle of descent that created the perception of vertical descent. As the experimenter adjusted the physical angle of descent, the observer reported whether he/she perceived the disk to fall vertically. For example, the experimenter adjusted the global motion direction of the disk 20 degrees to the right if the observer reported, "No. The disk is moving to the left about 20 degrees." The amount of adjustment became smaller as the observer reported that he/she saw the disk falling closer to vertical.

The stimulus was on until the observer made a response. In response to the observer’s comments, the experimenter changed the direction of the descending disk. The size of the illusion was measured as the angle in degrees between the direction perceived as vertical by the observer, and a true vertical line. There were twenty-four different conditions based on every combination of the following: three eccentricities (0, 15 and 30 degrees), two directions for the internal grating (0 and 180 degrees), and four moving speeds (6.7, 10, 13.3 and 20 deg/sec). Each condition was repeated four times and observers practiced two trials for each condition before data collection.

LU.CURVEBALL.PLOSONE.CM --USC-- OCT. 12, 2010

Carl Marziali | Newswise Science News
Further information:
http://www.usc.edu

More articles from Studies and Analyses:

nachricht A sudden drop in outdoor temperature increases the risk of respiratory infections
11.01.2017 | University of Gothenburg

nachricht Urbanization to convert 300,000 km2 of prime croplands
27.12.2016 | Mercator Research Institute on Global Commons and Climate Change (MCC) gGmbH

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>